Free Calculators

Enter your numbers in the fields — add as many as you need, or paste a whole list — to get the mean (average), median, mode, range, sum, and count at once.

A fast, free online calculator for everyday arithmetic. Type an expression or tap the buttons — it respects the order of operations and parentheses.

This free probability calculator lets you compute single-event probability, the complement rule, the addition rule for unions, and the multiplication rule for independent events — all with instant results.

Enter any one circle measurement — radius, diameter, circumference, or area — and this calculator instantly solves for the other three using exact geometry formulas.

Estimate how much concrete a slab, footing, or round column needs — in cubic yards, cubic feet, and cubic metres — plus how many 40, 60, or 80 lb pre-mix bags.

Compute a z-based confidence interval for a population mean from your sample mean, standard deviation, and sample size. Instantly see the margin of error and the lower and upper bounds at the 90%, 95%, or 99% confidence level.

Paste two equal-length lists of numbers (X and Y) to instantly compute the Pearson correlation coefficient r, the pair count n, and a plain-English reading of how strongly the two variables move together.

Turn any terminating decimal into a fully reduced fraction and mixed number, with each simplification step shown so you can follow the math.

Compute the straight-line distance and the midpoint between any two points in the coordinate plane, with the full distance-formula arithmetic shown for each result.

Expected value (EV) is the probability-weighted average of all possible outcomes, showing what you can expect on average over many trials. Use this calculator to add any number of outcome–probability pairs and instantly compute the EV.

Raise any base to any exponent — positive, negative, or fractional — and get the exact value instantly. A negative power gives a reciprocal and a fractional power gives a root.

Compute the factorial n! of any non-negative integer exactly — from small values like 5! = 120 up to massive results like 100!, with full digits, scientific form, and a digit count.

Find out what score you need on your final exam to reach your target course grade, based on your current grade and how much the final is worth.

Enter two fractions, pick an operation (+, −, ×, ÷), and this calculator returns the exact answer in lowest terms. It also shows the decimal value and, when the result is larger than 1, the equivalent mixed number — so you can read it however you need.

Calculate your vehicle's fuel efficiency in miles per gallon (MPG) or liters per 100 kilometers (L/100km) by entering your trip distance and fuel consumed. You can also convert between MPG and L/100km or estimate fuel cost per mile.

This free GPA calculator converts your letter grades into a credit-weighted grade point average on the standard US 4.0 scale. Just enter each course's grade and its credit hours, and it returns your GPA instantly. It uses the common unweighted scale (A = 4.0), so courses with more credits count proportionally more toward your final number.

Convert any raw score to a percentage grade in seconds. Enter your points earned and total possible points to get your percentage, letter grade, and GPA equivalent.

Find the greatest common divisor (GCD) and least common multiple (LCM) of any list of whole numbers in one click, using Euclid's algorithm with the steps shown.

Enter a value x and a base b and this calculator returns logₐ(x) using the change-of-base formula ln(x) ÷ ln(b), alongside the natural log (ln x) and common log (log₁₀ x). It handles any positive base except 1 and flags x ≤ 0, since the real logarithm is undefined there.

Calculate the margin of error for a survey or poll from your confidence level, sample size, and the observed proportion, using the standard normal-approximation formula MoE = Z·√(p(1−p)/n).

Enter two matrices (up to 5×5) and add, subtract, or multiply them, or find the determinant, inverse, and transpose of one — all worked out instantly in your browser.

Paste or type a list of numbers and instantly see the mean, median, mode, range, and standard deviation. It handles commas, spaces, and line breaks, and lists every mode when your data has more than one.

Find the exact midpoint between two points on a coordinate plane. Enter (x₁, y₁) and (x₂, y₂) to get the midpoint with each coordinate's step shown.

Find a mod b — the remainder when a is divided by b — along with the integer quotient and the always-positive (Euclidean) modulo for negatives.

Convert a test statistic into a p-value for the z, t, chi-square, or F distribution, with one- and two-tailed options and an automatic significance check at α = 0.05.

Estimate how much paint your project needs — in gallons and litres — from the wall area or room dimensions, number of coats, coverage rate, and any doors or windows to skip.

Compare a measured (experimental) value with the true (accepted) value to find the percent error and the absolute error — useful for labs and quality checks.

Work out percentages three ways: a percent of a number, what percent one value is of another, and the percentage change between two numbers.

Find the percentage increase or decrease from an original value to a new one, with the exact amount of change shown alongside the percentage.

Apply a percentage increase or decrease to any starting value and instantly see the new total along with the exact amount it went up or down.

Find the value at any percentile of a list of numbers using the linear-interpolation method, with the sorted data, interpolated rank, and full arithmetic shown for every result.

Pick a shape — square, rectangle, triangle, circle, or parallelogram — enter its measurements, and this calculator returns the perimeter instantly while showing the exact formula it used.

Compute permutations (nPr) and combinations (nCr) for any two whole numbers, along with the factorials n! and r!, instantly and with the formulas shown.

Check instantly whether any whole number from 2 upward is prime or composite, and see its full prime factorization with the smallest prime factor — all computed in your browser by trial division up to the square root.

Solve a proportion of the form a/b = c/d for whichever value you leave blank, using cross-multiplication — instantly and entirely in your browser.

Solve a right triangle from any two sides using the Pythagorean theorem a² + b² = c². Enter two of the legs a, b and the hypotenuse c, and this calculator finds the missing side along with the triangle's area and perimeter.

Enter the coefficients a, b and c to solve a·x² + b·x + c = 0. The calculator returns the roots (real or complex), the discriminant b² − 4ac, and the parabola's vertex, with the working shown.

Simplify a ratio like 8:12 to its lowest terms, see it as a decimal and a percentage, and solve equivalent ratios — all instantly in your browser.

Convert any whole number from 1 to 3999 into Roman numerals, and decode Roman numerals back into ordinary integers, instantly in your browser.

Round any number to a chosen number of decimal places or to the nearest 10, 100, or 1000, using round-half-up, floor (down), or ceiling (up).

This calculator tells you how many people you need to survey to estimate a proportion at a chosen confidence level and margin of error. Pick 90%, 95% or 99% confidence, set your margin of error and expected proportion, and — if you are sampling a small group — add the total population for a finite-population correction. The default of 95% confidence, ±5% margin of error and a 50% proportion returns the familiar answer of 385.

Convert any number to scientific notation (a × 10^b) and back to plain decimal form, and read E-notation too — type a plain number or a scientific value.

Count how many significant figures a number has, and round any value to a chosen number of significant figures — with leading and trailing zeros handled by the proper rules.

Find the slope of a line through two points, plus its y-intercept, full equation y = mx + b, and the angle it makes with the x-axis.

Calculate the area of a room or space in square feet (and square metres) for rectangles, squares, circles, triangles, and trapezoids — with optional cost and multi-room totals.

Find the principal square root of any number, switch to a cube root or any custom nth root, and see when the result is a perfect power — all in your browser.

Paste or type a list of numbers and instantly get the count, sum, mean, variance, and standard deviation. This calculator returns both the population standard deviation (σ, divided by n) and the sample standard deviation (s, divided by n−1) so you always have the right one for your situation.

Calculate the area of any triangle in two ways: from a base and its height, or from the lengths of all three sides using Heron's formula. Results update live as you type.

Evaluate sine, cosine, tangent and their inverses in degrees or radians, and solve a right triangle's missing sides and angles from any two known values.

Enter a list of numbers to instantly calculate their variance and standard deviation, whether you are analyzing a full population or working with a sample from a larger dataset.

Relate volume (m³) to area (m²) using a depth or thickness. Enter any two of volume, area, and depth and the calculator finds the third — handy for concrete, flooring, soil, and paint coverage.

Calculate a weighted average from a list of values and their weights — add or remove rows freely. Ideal for grades, prices, and survey scores.

Calculate the standard score (z-score) of any value: how many standard deviations it sits above or below the mean, computed instantly in your browser.