Most popular
The tools every student starts with
Final Grade Calculator
What you need on your final exam.
Word Counter
Words, characters, reading time — live as you type.
GPA Calculator
Standard 4.0 scale, weighted or unweighted.
Pomodoro Timer
Focus timer with a visual ring and breaks.
Mean, Median, Mode
Mean, median, mode, range, and quartiles from a data set.
Compound Interest
Growth with compounding, A = P(1 + r/n)^(nt).
Citation Generator
APA, MLA, Chicago, Harvard, and IEEE citations in seconds.
Periodic Table
Interactive, filterable, element details.
BMI Calculator
Body mass index from height and weight.
Time Zone Converter
Convert a time between any two time zones.
Recently added
The newest calculators and references on Knidox
Critical Value Calculator
Critical values for z, t, χ² and F from α and degrees of freedom.
Series & Convergence
Maclaurin expansions with intervals, plus every convergence test.
Limit Rules
Limit laws, standard limits, indeterminate forms, and asymptotes.
Laplace Transform Table
Transform pairs, shifting theorems and convolution.
Bond Energy
Estimate a reaction’s enthalpy from bonds broken and formed.
Quantum Numbers
Check whether a set of quantum numbers is allowed, and name it.
Oxidation Numbers
Assign an oxidation state to every element, with the rule used.
Function Composition
Build f(g(x)) and g(f(x)) by substitution, and evaluate both.
Radians & Degrees
Convert either way, with the exact multiple of π alongside.
Arc Length & Sector
Arc length, sector area and chord from a radius and an angle.
Shapiro–Wilk Test
Test a sample for normality, with the Q–Q plot alongside.
Levene’s Test
Test whether groups have equal spread, before an ANOVA or t-test.
Grades & study
GPA, grades, planning, and writing help
Math & computing
Algebra, calculus, statistics, and code
Sciences
Physics, chemistry, biology, and space
Engineering & money
Mechanics, circuits, economics, and finance
Everyday & languages
Languages, health, time, and the kitchen