All tools
Browse all 372 free academic tools — calculators, converters, and references across 23 subjects.
Final Grade Calculator
What you need on your final exam.
GPA Calculator
Standard 4.0 scale, weighted or unweighted.
Weighted GPA
AP / IB / Honors with bonus points.
Cumulative GPA
Combine multiple semesters into one.
Semester GPA
Single semester with credit hours.
Grade Needed
Reverse-calculate from your target.
Test Grade
Correct over total → percentage + letter.
Class Grade
All assignments, weighted average.
GPA Goal Planner
The GPA you need in remaining credits to hit a target cumulative GPA.
Grade Curve Calculator
Curve a raw score with flat, linear-scale, or square-root methods.
Rubric Grade Calculator
Score a project from rubric criteria — overall % and letter grade.
GPA Retake Calculator
Recalculate your GPA after retaking a course — replacement or averaging.
Word Counter
Words, characters, reading time — live as you type.
Citation Generator
APA, MLA, and Chicago citations in seconds.
Character Counter
With/without spaces. Tweet & SMS limits.
Reading Time
Estimate reading time at 250 WPM.
Words to Pages
By font, size, and line spacing.
Readability Score
Flesch-Kincaid, Gunning Fog, SMOG.
Words to Minutes
Speaking time from a word count.
Thesis Statement Builder
Topic + claim + reasons → a thesis.
Syllable Counter
Count syllables in words and text.
Lorem Ipsum Generator
Placeholder text by paragraphs, sentences, or words.
Word Frequency Counter
Count how often each word appears in your text.
Passive Voice Finder
Highlight likely passive-voice sentences in your writing.
Text Diff Checker
Compare two blocks of text and see what was added or removed.
Sentence Length Analyzer
Average sentence length and the longest sentences in your text.
Random Word Generator
Generate random words for brainstorming and writing prompts.
Line Sorter & Deduper
Sort lines alphabetically or by length and remove duplicates.
Text Cleaner
Trim whitespace, remove blank lines, and tidy up messy text.
Essay Outline Builder
Turn a thesis and key points into a structured essay outline.
Pomodoro Timer
Focus timer with a visual ring and breaks.
Exam Countdown
Days, hours, minutes to your exam.
Flashcards
Create, save, and study locally.
Cornell Notes
Editable template, exportable.
Reading Speed Test
Measure your reading WPM.
Typing Speed Test
WPM and accuracy, live feedback.
Study Planner
Split weekly hours across subjects.
Mind Map Maker
Outline → branching mind map.
Spaced Repetition Scheduler
Next review interval for a flashcard using the SM-2 algorithm.
Forgetting Curve Calculator
Estimated memory retention over time from the forgetting curve.
Study Hours Planner
Weekly and semester study hours from your credit load.
Focus & Break Planner
Fit focus and break cycles into your time with proven work rhythms.
Attendance Calculator
How many classes you can miss and stay above the required attendance %.
Class Schedule Maker
Build a printable weekly class timetable, saved in your browser.
Reading Schedule Planner
Split a reading assignment into pages per day before it’s due.
Scientific Calculator
Full function with history.
Percentage Calculator
Percent of, increase, decrease, change.
Quadratic Solver
ax² + bx + c = 0, step by step.
Matrix Calculator
Add, multiply, inverse, determinant.
Trigonometry
sin, cos, tan + inverse functions.
Fraction Calculator
+ − × ÷ with simplification.
Derivative Calculator
Step by step, with the rules used.
Integral Calculator
Definite & indefinite, with steps.
System of Equations
2×2 and 3×3 linear systems.
Polynomial Roots
All real and complex roots.
Limit Calculator
Estimate a limit from both sides.
Logarithm Calculator
log, ln, log₂, and any base.
Factorial Calculator
n! exactly, with expansion.
Combinations & Permutations
nCr and nPr, exact.
Fraction ↔ Decimal ↔ %
Convert between all three forms.
Slope Calculator
Slope, intercept, and line equation from two points.
GCD & LCM
Greatest common divisor, least common multiple, and prime factors.
Significant Figures
Count significant figures and round to a given number.
Ratio Calculator
Simplify ratios and solve proportions.
Sequences
Arithmetic and geometric nth term and sum.
Vector Calculator
Add, subtract, dot/cross product, magnitude.
Complex Numbers
Add, multiply, modulus, and conjugate.
Exponent Calculator
Powers and the laws of exponents.
Simplify Radicals
Reduce a square root to simplest radical form.
Modulo Calculator
Remainder of a division (a mod n).
Percent Error
Compare a measured value to the true value.
Prime Number Checker
Test if a number is prime and factor it.
Rounding Calculator
Round to decimals, places, or significant figures.
Long Division Calculator
Divide two numbers with the full long-division working shown.
Synthetic Division Calculator
Divide a polynomial by (x − c) with the synthetic-division steps.
Completing the Square
Rewrite a quadratic as a(x − h)² + k, step by step.
Partial Fractions Calculator
Decompose a rational function into partial fractions with steps.
Polynomial Long Division
Divide one polynomial by another with the long-division working.
Prime Factorization Calculator
Break a number into its prime factors with the division steps.
Periodic Table
Interactive, filterable, element details.
Molar Mass
Enter a formula → molecular weight.
pH Calculator
From H⁺ concentration or Ka.
Equation Balancer
Auto-balance chemical equations.
Stoichiometry Calculator
Mole ratios and masses from a reaction.
Dilution Calculator
Solve C₁V₁ = C₂V₂ for any variable.
Ideal Gas Law
PV = nRT, solve for any variable.
Concentration Calculator
Molarity, molality, and normality.
Empirical Formula
Simplest whole-number atom ratio.
Buffer pH Calculator
Henderson–Hasselbalch buffer pH.
Percent Yield
Actual ÷ theoretical yield × 100.
Limiting Reagent
Find the limiting reactant from moles and coefficients.
Half-Life Calculator
Radioactive decay: remaining amount over time.
Gas Laws
Boyle, Charles, and the combined gas law.
Titration Calculator
Find unknown concentration from titration data.
Percent Composition
Mass percent of each element in a formula.
Boiling & Freezing Point
Colligative shifts: ΔT = i·K·m.
Electron Configuration
Electron configuration of any element.
Equilibrium Constant (K)
Compute K from equilibrium concentrations.
Mole Calculator
Convert between grams, moles, and particles.
Henderson-Hasselbalch Calculator
Buffer pH from pKa and the acid/base ratio.
Ka to pKa Converter
Convert between the acid constant Ka and pKa.
Beer-Lambert Law Calculator
Absorbance from molar absorptivity, path length, and concentration.
Reaction Rate Calculator
Reaction rate from the rate constant and reactant concentrations.
Arrhenius Equation Calculator
Rate constant or activation energy from the Arrhenius equation.
Nernst Equation Calculator
Cell potential from standard potential and the reaction quotient.
Kinematics Solver
SUVAT equations of motion.
Projectile Motion
Range, height, and flight time.
Force Calculator
F = ma, solve for any variable.
Density Calculator
ρ = m / V, solve for any variable.
Wave Speed Calculator
v = fλ, speed, frequency, wavelength.
Pendulum Period
T = 2π√(L/g), period or length.
Specific Heat
Q = mcΔT, solve for any variable.
Lens Equation
1/f = 1/dₒ + 1/dᵢ, with magnification.
Kinetic Energy
KE = ½mv², solved for any variable.
Potential Energy
Gravitational PE = mgh.
Work & Power
Work = force × distance; power = work ÷ time.
Momentum & Impulse
p = mv and impulse = force × time.
Free Fall
Drop time and impact speed under gravity.
Torque Calculator
Torque τ = r × F × sin θ.
Centripetal Force
F = mv² ÷ r for circular motion.
Gravitational Force
Newton's law of gravitation, F = G·m₁m₂ ÷ r².
Hooke's Law
Spring force F = k × x.
Efficiency
Useful output ÷ total input × 100.
Snell's Law
Refraction: n₁ sin θ₁ = n₂ sin θ₂.
Pressure Calculator
Pressure from force and area, P = F ÷ A.
Acceleration Calculator
Acceleration from a change in velocity over time.
Friction Calculator
Friction force from the coefficient and normal force.
Doppler Effect Calculator
Observed frequency shift for a moving source or observer.
Escape Velocity Calculator
Speed needed to escape a planet or star from its mass and radius.
Orbital Period Calculator
Orbital period from the semi-major axis and central mass.
Bernoulli Equation Calculator
Pressure or speed along a streamline from Bernoulli’s equation.
Stefan-Boltzmann Calculator
Radiated power from temperature, area, and emissivity.
Projectile Range Calculator
Range, max height, and flight time from launch speed and angle.
Terminal Velocity Calculator
Terminal velocity from mass, area, drag coefficient, and air density.
Punnett Square
Mono- and dihybrid crosses, visualized.
Hardy-Weinberg
Allele & genotype frequencies.
Allele Frequency
p and q from genotype counts.
DNA Codon Translator
Translate DNA/RNA into amino acids.
Serial Dilution
Concentration at every tube.
Dihybrid Cross
Two-trait Punnett square and 9:3:3:1 ratio.
Surface-Area-to-Volume
SA:V ratio for cells and shapes.
Population Growth
Exponential and logistic growth models.
Microscope Magnification
Total magnification from objective and eyepiece.
Michaelis-Menten Calculator
Reaction rate from Vmax, Km, and substrate concentration.
Cell Doubling Time Calculator
Doubling time and growth rate from a population over time.
Osmolarity Calculator
Osmolarity from molar concentration and particles per formula unit.
DNA Molecular Weight Calculator
Molecular weight of DNA or RNA from its length.
GC Content Calculator
Percentage of G and C bases in a DNA sequence.
DNA Concentration Calculator
Nucleic acid concentration and purity from A260/A280 readings.
Standard Deviation
Mean, variance, and SD for any dataset.
P-Value Calculator
From a test statistic and distribution.
Confidence Interval
For a mean or proportion.
Z-Score Calculator
Standardize a value and find its percentile.
Normal Distribution
Probabilities under the bell curve.
T-Test Calculator
One- and two-sample tests with p-value.
Chi-Square Calculator
Goodness-of-fit from observed vs expected.
Correlation Calculator
Pearson's r, r², and significance.
Sample Size Calculator
Participants needed for a margin of error.
ANOVA Calculator
One-way analysis of variance, F-table.
Mean, Median, Mode
Mean, median, mode, range, and quartiles from a data set.
Linear Regression
Least-squares line, slope, intercept, and r².
Percentile Calculator
Percentile rank of a value, and value at a percentile.
Binomial & Poisson
Binomial and Poisson probabilities.
Probability Calculator
Single and combined event probabilities.
Effect Size Calculator
Cohen’s d effect size from two group means and standard deviations.
Margin of Error Calculator
Margin of error for a survey proportion at a confidence level.
Five-Number Summary
Min, Q1, median, Q3, max, IQR, and outliers with a box plot.
Weighted Mean Calculator
Weighted average from value and weight pairs.
Geometric Mean Calculator
Geometric mean of a set of positive numbers.
Coefficient of Variation
Relative variability — standard deviation as a percent of the mean.
GPA Scale Converter
Convert a GPA between US, UK, German, Indian, and percentage scales.
IELTS ↔ TOEFL
Convert between IELTS band and TOEFL iBT score.
SAT ↔ ACT
Convert between SAT total and ACT composite scores.
Duolingo → IELTS
Convert a Duolingo English Test score to an IELTS band.
GRE Percentile
GRE Verbal/Quant scaled score to percentile.
GMAT Percentile
GMAT total score (200–800) to percentile.
Old SAT → New SAT
Convert between the 2400 and 1600 SAT scales.
CEFR ↔ IELTS / TOEFL
Map a CEFR level (A1–C2) to IELTS bands and TOEFL scores.
PTE ↔ IELTS
Convert PTE Academic scores to IELTS bands (and approx. TOEFL).
IB → GPA
Estimate a US 4.0 GPA from IB diploma grades.
A-Level → GPA
Estimate a US 4.0 GPA from A-Level grades.
ECTS Credit Converter
Convert ECTS credits to US credit hours and study hours.
UK Class ↔ GPA
Map a UK degree classification to an approximate US GPA.
Percentage to Letter Grade
Convert a percentage to a US letter grade and GPA.
IELTS Band Score Calculator
Overall IELTS band from your four section scores, with correct rounding.
ACT Composite Score Calculator
ACT composite score from your English, Math, Reading, and Science scores.
SAT Superscore Calculator
Your best SAT superscore from the top section scores across sittings.
German Grade Converter
Convert a foreign grade to the German 1–5 scale with the Bavarian formula.
Indian CGPA to Percentage
Convert between CGPA and percentage using the CBSE and 10-point scales.
TOEFL Score Calculator
TOEFL iBT total from your four section scores, with a CEFR level.
Canadian GPA Converter
Convert a Canadian percentage to a 4.0 GPA and letter grade.
Australian GPA (7-Point)
Convert an Australian mark to the 7-point GPA scale and US 4.0.
French Grade to GPA
Convert a French grade out of 20 to a US 4.0 GPA and mention.
Chinese GPA Converter
Convert a Chinese percentage to a 4.0 GPA using the WES scale.
SAT Score to Percentile
The national percentile for an SAT total score (400–1600).
GCSE 9-1 Grade Converter
Convert between GCSE 9–1 numeric grades and old A*–G letters.
Unit Converter
Length, mass, temperature, volume, and more.
Random Number & Picker
Random numbers or pick a name from a list.
Study Abroad Budget
Total cost of a program in one currency.
Wheel of Names
Spin a wheel to pick a random winner.
Markdown Editor
Write notes in Markdown, live preview.
Case Converter
UPPER, lower, Title, Sentence, camel, snake, kebab.
Color Converter
Convert between HEX, RGB, and HSL.
Password Generator
Strong random passwords, in your browser.
Fuel Cost Calculator
Trip fuel cost from distance, fuel economy, and price.
Fuel Economy Converter
Convert between MPG, L/100km, and km/L fuel economy.
Greek Alphabet
All 24 letters with names and uses.
Math Symbols
Logic, sets, operators, calculus.
Roman Numeral Converter
Numbers ↔ Roman numerals, 1–3999.
Number Base Converter
Binary, octal, decimal, hex.
Grading Systems Explained
Grades by country: US, UK, Germany…
Academic Calendar Comparison
When the school year starts, by country.
Scientific Notation Converter
a × 10ⁿ, engineering, and E-notation.
Metric Prefix Converter
Convert between SI prefixes (kilo, milli, …).
Physical Constants
Reference table of common physics constants.
Multiplication Table
Times tables grid up to any number.
Morse Code Translator
Translate text to and from Morse code.
NATO Phonetic Alphabet
Spell text with the NATO phonetic alphabet (Alfa, Bravo, …).
Number to Words Converter
Write numbers in words for cheques and formal writing.
Trig Identities
Pythagorean, double-angle, sum, and half-angle trig identities to copy.
Derivative Rules
Power, product, quotient, and chain rules plus common derivatives.
Integral Table
Common indefinite integrals and integration rules to copy.
Unit Circle
Angles in degrees and radians with sine, cosine, and tangent values.
Algebra Formulas
Quadratic formula, factoring, exponent, and logarithm rules to copy.
Geometry Formulas
Area, perimeter, surface area, and volume formulas for common shapes.
Spanish Verb Conjugator
Conjugate Spanish verbs, 5 tenses.
French Verb Conjugator
Conjugate French verbs, 4 tenses.
German Verb Conjugator
Präsens, Präteritum, and Futur I.
Italian Verb Conjugator
Conjugate Italian verbs, 4 tenses.
Latin Noun Declension
Decline Latin nouns, all six cases.
Latin Verb Conjugation
Present, imperfect, future — 5 conjugations.
French Numbers in Words
Write any number in French, with the 70/80/90 forms handled.
Spanish Numbers in Words
Write any number in Spanish, with gender and apocope handled.
German Numbers in Words
Write any number in German, as one compound word.
German Cases & Articles
Der/die/das and ein declension across all four German cases.
False Friends Reference
Words that look alike across languages but mean something else.
IPA Pronunciation Reference
IPA vowels and consonants with example words and descriptions.
Compound Interest
Growth with compounding, A = P(1 + r/n)^(nt).
Simple Interest
Interest = principal × rate × time.
Loan & EMI Calculator
Monthly payment, total interest, and schedule.
Discount Calculator
Sale price and amount saved from a percent off.
Tip Calculator
Tip amount and total, split across people.
Savings Goal
Monthly saving needed to reach a target.
ROI Calculator
Return on investment, gain, and annualized return.
Markup & Margin
Profit markup and margin from cost and price.
Break-Even Calculator
Units to sell to cover fixed and variable costs.
Inflation Calculator
How prices and buying power change over time.
Salary Converter
Hourly, weekly, monthly, and annual pay.
Sales Tax Calculator
Tax amount and total from a price and rate.
Mortgage Calculator
Monthly payment, total interest, and amortization from loan terms.
APR to APY Converter
Convert between APR and APY for any compounding frequency.
Credit Card Payoff Calculator
Months to clear a card balance and the total interest paid.
50/30/20 Budget Calculator
Split take-home pay into needs, wants, and savings.
Net Worth Calculator
Total assets minus liabilities to find your net worth.
Rule of 72 Calculator
Estimate how long an investment takes to double.
Cost Per Unit Calculator
Find the unit price and compare which option is cheaper.
Present Value Calculator
Discount a future amount back to what it is worth today.
Future Value Calculator
Grow a present sum to its value after compounding.
CAGR Calculator
Compound annual growth rate between a start and end value.
Annuity Payment Calculator
Payment for a present value or to reach a savings goal.
NPV Calculator
Net present value of a cash-flow series at a discount rate.
Depreciation Calculator
Straight-line depreciation and a year-by-year schedule.
Profit Margin Calculator
Gross, operating, and net profit margin from revenue and costs.
Truth Table Generator
Truth table for any boolean expression.
Two's Complement
Signed binary ↔ decimal conversion.
Boolean Algebra
Evaluate and simplify boolean expressions.
ASCII & Unicode Lookup
Characters ↔ ASCII / Unicode code points.
Bitwise Calculator
AND, OR, XOR, NOT, and bit shifts.
Data Storage Converter
Bytes, KB, MB, GB, TB — binary and decimal.
Base64 Encode & Decode
Convert text to and from Base64.
URL Encode & Decode
Percent-encode text for URLs, or decode it back.
JSON Formatter
Pretty-print, minify, and validate JSON in your browser.
SHA-256 Hash Generator
Generate a SHA-256 hash of any text.
HTML Entity Encode & Decode
Convert characters to HTML entities and back.
IP Subnet Calculator
Network, broadcast, mask, and host range from an IP and CIDR.
Regex Tester
Test a regular expression against text and see matches.
CSV to JSON Converter
Convert CSV to a JSON array and back, in your browser.
Text to Binary Converter
Convert text to 8-bit binary and decode binary back to text.
Caesar Cipher
Encode or decode a Caesar shift cipher, including ROT13.
Vigenère Cipher
Encode or decode a Vigenère cipher with a keyword.
Big-O Complexity Reference
Common time complexities with examples and a growth comparison.
Hamming Distance Calculator
Count the differing positions between two equal-length strings.
Hexadecimal Calculator
Add, subtract, multiply, and divide hexadecimal numbers.
IEEE 754 Float Converter
The sign, exponent, and mantissa bits of a 32-bit float.
Set Operations Calculator
Union, intersection, and difference of two sets.
Gray Code Converter
Convert between binary and reflected Gray code.
Time Zone Converter
Convert a time between any two time zones.
Date Calculator
Days between dates, or add/subtract days.
Age Calculator
Exact age in years, months, and days.
Stopwatch & Timer
Stopwatch with laps and a countdown timer.
Business Days Calculator
Count working days (weekdays) between two dates.
Unix Timestamp Converter
Convert between Unix epoch time and a human date.
Week Number Calculator
Find the ISO week number for any date.
Days Until Date
Count down the days until any future date.
Time Duration Calculator
Add, subtract, or find the duration between two times.
Hours Calculator
Hours worked from a start and end time, minus breaks.
Leap Year Checker
Check if a year is a leap year and why.
BMI Calculator
Body mass index from height and weight.
BMR & Calorie Calculator
Basal metabolic rate and daily calories (TDEE).
Body Fat Calculator
Estimate body-fat percentage with the US Navy tape method.
TDEE Calculator
Total daily energy expenditure from BMR and activity level.
Macro Calculator
Split daily calories into protein, carbohydrate, and fat grams.
Water Intake Calculator
Estimate daily water needs from body weight and activity.
Ideal Weight Calculator
Healthy weight range from height with classic formulas.
Calorie Goal Calculator
Daily calories to lose, maintain, or gain weight at a target rate.
Heart Rate Zone Calculator
Training heart-rate zones from your age and resting rate.
Sleep Cycle Calculator
Best bedtimes or wake times based on 90-minute sleep cycles.
Running Pace Calculator
Pace, speed, distance, or finish time for runs and races.
Steps to Calories Calculator
Distance and calories burned from your step count.
Calories Burned Calculator
Calories burned from an activity’s MET value, weight, and time.
One-Rep Max Calculator
Estimate your 1RM from reps and weight with the Epley and Brzycki formulas.
Body Surface Area Calculator
Calculate BSA from height and weight with the Mosteller and Du Bois formulas.
Waist-to-Hip Ratio Calculator
Work out your waist-to-hip ratio and WHO health-risk category.
VO₂ Max Estimator
Estimate VO₂ max from a Cooper run test or your resting heart rate.
Lean Body Mass Calculator
Estimate lean body mass with the Boer and James formulas.
Protein Intake Calculator
Find your daily protein target in grams by body weight and goal.
Distance & Midpoint
Distance and midpoint between two points.
Pythagorean Theorem
Solve a² + b² = c² for any missing side.
Area & Volume
Area and volume of common 2D and 3D shapes.
Triangle Solver
Solve a triangle from sides and angles (SSS, SAS, ASA, AAS).
Circle Calculator
Radius, diameter, circumference, and area of a circle.
Sphere Calculator
Volume and surface area of a sphere from its radius.
Cylinder Calculator
Volume and surface area of a cylinder from radius and height.
Cone Calculator
Volume, slant height, and surface area of a cone.
Rectangular Prism Calculator
Volume, surface area, and diagonal of a box from its sides.
Regular Polygon Calculator
Area, perimeter, and interior angle of a regular polygon.
Recipe Scaler
Scale recipe ingredients up or down by a factor or new serving size.
Cooking Measurement Converter
Convert between teaspoons, tablespoons, cups, millilitres, and ounces.
Oven Temperature Converter
Convert oven temperatures between Fahrenheit, Celsius, and gas mark.
Cups to Grams Converter
Convert cups to grams for flour, sugar, butter, and more.
Butter Converter
Convert butter between sticks, tablespoons, cups, grams, and ounces.
Air Fryer Converter
Adjust oven time and temperature for an air fryer.
Ohm’s Law
Voltage, current, resistance, power.
Resistors (Series & Parallel)
Total resistance of resistors in series or parallel.
Resistor Color Code
Resistance and tolerance from the color bands.
Voltage Divider Calculator
Output voltage from two resistors in a divider.
LED Resistor Calculator
Series resistor value for an LED from supply and forward voltage.
Capacitor Energy Calculator
Energy and charge stored in a capacitor from capacitance and voltage.
RC Time Constant Calculator
Time constant τ = RC and the charge/discharge curve.
Capacitors in Series & Parallel
Total capacitance of capacitors wired in series or parallel.
Reactance Calculator
Capacitive and inductive reactance at a given frequency.
Battery Life Calculator
Estimate runtime from battery capacity and load current.
Beam Deflection Calculator
Maximum deflection of a beam under a central or end point load.
Stress and Strain Calculator
Axial stress, strain, and elongation from force and dimensions.
Young’s Modulus Calculator
Elastic modulus from stress and strain, or axial deformation.
Torque to Power Calculator
Convert between torque, rotational speed (RPM), and power.
Gear Ratio Calculator
Gear ratio with output speed and torque from tooth counts.
Factor of Safety Calculator
Factor of safety from material strength and applied stress.
Note to Frequency Calculator
Frequency of any musical note, and the nearest note to a frequency.
Tempo to Delay Calculator
Delay and note-value times in milliseconds from a tempo in BPM.
Musical Interval Calculator
Frequency ratio and cents between two notes or a semitone count.
Audio File Size Calculator
Uncompressed audio file size from sample rate, bit depth, and length.
Harmonic Series Calculator
Overtone frequencies of the harmonic series from a fundamental.
Music Transposition Calculator
Transpose a note or key by a number of semitones.
Redshift to Velocity Calculator
Recession velocity from redshift z, low-z and relativistic.
Light Travel Time Calculator
How far light travels in a time, or how long it takes over a distance.
Stellar Parallax Calculator
Distance to a star from its parallax angle, in parsecs and light-years.
Schwarzschild Radius Calculator
Event-horizon radius of a black hole from its mass.
Surface Gravity Calculator
Surface gravity of a planet or star from its mass and radius.
Angular Size Calculator
Apparent angular size of an object from its size and distance.
Planet Weight Calculator
See what you would weigh on every planet, the Moon, and the Sun.
Moon Phase Calculator
Find the Moon phase and illumination for any date.
Wien’s Law Calculator
Convert between a blackbody’s temperature and its peak wavelength.
Hubble’s Law Calculator
Relate a galaxy’s recession velocity and distance with v = H₀d.
Telescope Magnification Calculator
Magnification, focal ratio, and exit pupil from your telescope and eyepiece.
Distance Modulus Calculator
Solve for distance, apparent, or absolute magnitude from the distance modulus.
Price Elasticity of Demand
Elasticity of demand from price and quantity, midpoint method.
Real GDP Calculator
Real GDP, nominal GDP, and the GDP deflator from any two.
CPI Inflation Rate Calculator
Inflation rate between two Consumer Price Index values.
Consumer & Producer Surplus
Consumer, producer, and total surplus from a linear market.
Comparative Advantage Calculator
Opportunity cost and comparative advantage for two producers.
Spending Multiplier Calculator
The multiplier and change in GDP from the marginal propensity to consume.