Free math & number tools — percentages, fractions, statistics, equations
The math you actually look up: a percentage calculator that handles increase, decrease and 'what percent of', fraction and GCD/LCM tools that show the steps, a statistics calculator for mean, median and standard deviation, plus a quadratic solver and prime checker. Each one shows the working, not just the answer, so it doubles as a quick way to check homework or a spreadsheet.
Percentage Calculator (% of, what %, % change)
Three percentage calculators in one: 'X% of Y', 'X is what % of Y', and percentage change between two values.
GPA Calculator (4.0 scale, weighted by credits)
Calculate your GPA on the 4.0 scale, weighted by course credit hours. Add as many courses as you need.
Number to Words Converter — English Word Form
Convert any number up to 999 quadrillion into English words. Shows the full word form, comma-formatted number, and word count.
Number Base Converter (binary, octal, decimal, hex)
Convert numbers between binary, octal, decimal, and hexadecimal. Validates input for the chosen base and shows all four representations.
Random Number Generator (cryptographically secure, unique mode)
Generate random integers in any range using your browser's secure random API. Optionally enforce uniqueness for lottery, raffle, or sample-without-replacement use cases.
Paint Calculator (gallons or liters from room size)
Calculate how much paint you need based on room dimensions, number of coats, and doors/windows. Output in liters or gallons.
Aspect Ratio Calculator (preserve ratio when resizing)
Calculate width or height to preserve a target aspect ratio. Common ratios (16:9, 9:16, 1:1, 4:3, 21:9) one-click presets included.
Dice Roller (d4 to d100, with modifier and history)
Roll any number of dice with any number of sides. Cryptographically random, with modifier (+N), running total, and roll history.
Statistics Calculator (mean, median, std dev, quartiles)
Compute mean, median, mode, standard deviation, variance, range, quartiles, and more from a list of numbers. Sample or population mode.
Prime Number Checker (with factorization)
Check whether a number is prime. If not, see its prime factorization. Plus the next and previous prime numbers.
Quadratic Equation Solver (ax² + bx + c = 0)
Solve any quadratic equation. Returns real or complex roots, the discriminant, and the parabola's vertex coordinates.
Fraction Calculator (add, subtract, multiply, divide)
Add, subtract, multiply, or divide two fractions. Returns simplified form, decimal equivalent, and mixed-number representation.
GCD & LCM Calculator (with prime factorizations)
Find the greatest common divisor (GCD) and least common multiple (LCM) of two or more integers, plus each number's prime factorization.
Triangle Calculator (right angle, SSS, SAS)
Compute a triangle's area, perimeter, sides, and angles. Three modes: right triangle (Pythagorean), three sides (SSS), or two sides + included angle (SAS).
Scientific Notation Converter (decimal ↔ scientific)
Convert decimal numbers to/from scientific (1.23 × 10^4) and engineering (1.23e3) notation. Bidirectional, with E-notation output.
Factorial / Permutations / Combinations Calculator
Calculate n! (factorial), P(n,k) permutations, and C(n,k) combinations. Handles large integers via BigInt up to n=5000.
Prime Factorization Calculator — Find Prime Factors Instantly
Enter any integer up to 1 billion to find its prime factorization. Shows each prime factor with its exponent and the exponential notation.
Math Expression Calculator — evaluate any formula online
Type any math expression and get an instant result. Supports arithmetic, powers, roots, trig, logs, and more.
Number Sequence Generator — Arithmetic, Geometric, Fibonacci & More
Generate arithmetic, geometric, Fibonacci, square, prime, and triangular number sequences. Shows the full sequence, sum, and formula.
Circle Calculator — Area, Circumference, Diameter, Radius
Enter any one circle measurement — radius, diameter, area, or circumference — and instantly get all the others. Supports arc length and sector area for a given central angle.
Probability Calculator — Basic, Permutations, Combinations, Dice
Calculate probabilities, permutations (nPr), combinations (nCr), and dice roll outcomes. Four dedicated tabs cover every common probability problem.
Percent Error Calculator — Experimental vs Theoretical
Calculate percent error between an experimental (measured) value and a theoretical (accepted) value. Shows signed error, absolute error, and the difference.
Fibonacci Calculator — Nth Term and Sequence
Calculate any Fibonacci number up to the 100th term, or list the first 50 terms of the sequence. Supports large numbers accurately.
Matrix Calculator — Add, Multiply, Determinant
Perform matrix addition, subtraction, multiplication, transpose, and determinant on 2×2 or 3×3 matrices — all in your browser.
Pixel Density Calculator — PPI for Any Screen
Calculate pixels per inch (PPI) for any display. Enter resolution and screen size; get PPI, megapixels, and display quality rating instantly.
Grade Calculator — Weighted Average & Letter Grade
Calculate your weighted average grade, letter grade, and GPA equivalent from multiple assignments or exams.
Pythagorean Theorem Calculator — Find Any Side
Enter any two sides of a right triangle to instantly find the missing side, plus area, perimeter, and all three angles.
Ohm's Law Calculator — Voltage, Current, Resistance & Power
Calculate voltage, current, resistance, or power using Ohm's Law (V=IR) and the power formula (P=VI). Shows all four values with smart unit display.
Significant Figures Calculator — Count & Round Sig Figs
Count significant figures in any number or round to a specified number of sig figs. Shows a digit-by-digit breakdown and scientific notation.
Geometric Shapes Calculator — Volume & Surface Area
Calculate volume, surface area, and key dimensions for 6 common 3D shapes: sphere, cylinder, cone, cube, rectangular prism, and triangular prism.
Percentage Change Calculator — Increase & Decrease
Calculate percentage change between two values, find a new value after a percentage change, or reverse-calculate the original value from a known result.
Slope Calculator – Two Points to Slope & Angle
Find the slope, angle, and grade from two points on a line.
Square Footage Calculator – Area in ft²
Calculate the area of a room or space in square feet.
Midpoint Calculator – Midpoint of Two Points
Find the midpoint between two points on the coordinate plane.
Concrete Calculator – Cubic Yards & Meters
Estimate the concrete volume needed for a slab in cubic yards.
Z-Score Calculator – Standard Score
Calculate the z-score (standard score) of a value.
Gravel Calculator - Estimate Yards & Tons
Estimate the gravel you need for a driveway, path, or landscaping in cubic yards and tons.
Cylinder volume calculator (cm³ and liters)
Calculate the volume of a cylinder from its radius and height.
Kinetic Energy Calculator (KE = ½mv²)
Calculate kinetic energy from mass and velocity in joules.
Density Calculator (Mass / Volume)
Calculate density from mass and volume in g/cm³.
Board Foot Calculator - Lumber BF Measurement
Calculate board feet for lumber from thickness, width, length, and quantity.
Box Volume Calculator (cm to liters)
Calculate the volume of a rectangular box from length, width and height in centimeters.
Tile Calculator - Tiles Needed for Any Room
Calculate how many square tiles you need for a room, with a 10% waste allowance.
Molarity Calculator (mol/L to moles)
Calculate moles of solute from molarity and volume.
Average Speed Calculator (km/h)
Calculate average speed from distance and time, in km/h.
Proportion Calculator: Solve a / b = c / x
Solve the proportion a / b = c / x and find x by cross-multiplication.
Sphere Volume Calculator (4/3·π·r³)
Calculate the volume of a sphere from its radius in cm³ and liters.
Cone Volume Calculator (cm³ and Liters)
Calculate the volume of a cone from its radius and height.
Logarithm calculator - compute log base b of any value
Calculate the logarithm of a value to any base.
Combination Calculator (nCr) — Choose r from n
Calculate the number of combinations nCr for choosing r items from n when order does not matter.
Permutation Calculator (nPr)
Calculate the number of ordered arrangements nPr of r items from n.
Exponent Calculator - Raise Base to a Power
Raise any base to an exponent (power) and get the result instantly.
Modulo Calculator - Remainder of a mod b
Calculate a mod b, the remainder after dividing a by b.
Square Root Calculator (√ and ∛)
Find the square root and cube root of any non-negative number instantly.
Half-life Calculator — Exponential Decay
Calculate the amount remaining after radioactive or substance decay using a half-life.
Ratio Simplifier — Reduce a:b to Lowest Terms
Simplify any ratio a:b to its lowest terms instantly.