Math Calculators
Everyday math, statistics, and conversions — instant and private.
These free math calculators handle the arithmetic, statistics, and conversions that come up every day: averages and standard deviation, ratios and proportions, fractions and decimals, square footage, unit conversions, random numbers, and a full scientific calculator. Each one shows its method and a worked example, so the result is never a black box.
Everything runs entirely in your browser — your numbers never touch a server. The calculations use standard, widely accepted definitions with full-precision arithmetic and rounding only for display, and every engine function is unit-tested against the awkward edge cases so you can rely on the answer.
11 math calculators
Average Calculator
Find the mean, median, sum, min, max, and range of a list of numbers.
GPA Calculator
Calculate your grade point average on the 4.0 scale, weighted by credits.
Fraction to Decimal Converter
Convert any fraction to a decimal (and a percentage), with the simplified form.
Random Number Generator
Generate random numbers in any range — with optional unique values.
Ratio Calculator
Simplify ratios and solve proportions (A : B = C : ?).
Standard Deviation Calculator
Find standard deviation, variance, and mean for a data set.
Percent Error Calculator
Compare a measured value to the true value as a percentage.
Unit Converter
Convert between length, weight, temperature, area, volume, speed, time, and data units instantly.
Scientific Calculator
A full scientific calculator — trig, logs, powers, factorials, and constants.
Grade Calculator
Weighted grade average, letter grade, GPA — and the score you need on the final.
Square Footage Calculator
Calculate area in square feet for rooms and common shapes.
Guides
Standard Deviation Explained: What It Is and How to Calculate It
What standard deviation measures, population vs sample, a step-by-step calculation for a 5-number dataset, the formula, real-world uses, and the 68-95-99.7 rule.
4 min read
KM to Miles Conversion Chart (+ How to Convert)
Convert kilometers to miles with an exact formula, a quick reference chart for 1–100 km, a mental-math shortcut, and the common distances runners and drivers actually use.
4 min read
How to Calculate a Weighted Grade (With Examples)
How to calculate a weighted grade step by step: the formula, a worked example with three assignments, how to find the score you need on your final, and a GPA table.
5 min read
Converting Fractions to Decimals (and When They Repeat)
How to convert any fraction to a decimal, a table of common conversions, the rule for when a decimal terminates vs repeats, and how to turn fractions into percentages.
1 min read
How to Calculate Your GPA (4.0 Scale Explained)
How GPA works on the 4.0 scale: the grade-to-points table, the credit-weighted formula, a worked example, and the difference between weighted and unweighted GPA.
1 min read
Mean vs Median: Which "Average" Should You Use?
The mean and the median are both "averages" but can tell very different stories. Learn how to calculate each, when the mean misleads, and which to use for skewed data like incomes.
2 min read
Frequently asked questions
Which math calculator should I use?
For summarizing data, use the Average Calculator (mean, median, range) or the Standard Deviation Calculator (spread). For number forms, use the Fraction to Decimal Converter or the Ratio Calculator. Use the Unit Converter for conversions, the Square Footage Calculator for area, and the Scientific Calculator for trigonometry, logarithms, and powers.
Are these math calculators accurate?
Yes. They use standard mathematical definitions with full-precision calculation and rounding only for display, and every engine function is unit-tested against edge cases like zero, negatives, division by zero, and very large or small numbers.
Do these calculators store my data?
Not on our servers. Every calculation happens locally in your browser, and nothing you enter is uploaded or logged. Your last inputs are saved in this browser's local storage so you don't have to retype them; clearing your site data removes them.
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