Math Calculators

ArrayKit's math calculators cover arithmetic, algebra, geometry and statistics, and many show the working. For everyday numbers, the Percentage Calculator finds X% of Y, what percent X is of Y, and percent change, the Fraction Calculator does fraction arithmetic and simplifies the result, and the Scientific Calculator evaluates typed expressions with trig, logs, powers, roots and factorials. For algebra, the Quadratic Formula Calculator solves ax²+bx+c=0 with the discriminant and vertex, the Slope Calculator writes the equation of a line through two points, and the Matrix Calculator multiplies, transposes and inverts matrices. For statistics, the Standard Deviation Calculator gives population and sample results step by step, the Z-score Calculator turns a value into normal-distribution probabilities, and the Random Number Generator draws numbers in a range, unique if needed. For geometry, the Pythagorean Theorem Calculator finds a missing side of a right triangle, the Right Triangle Calculator and Triangle Calculator solve sides and angles, and the Area Calculator, Volume Calculator and Circle Calculator measure common shapes. The Mean, Median, Mode, Range Calculator summarizes a data set, the Confidence Interval Calculator and Sample Size Calculator handle sampling math, and the LCM Calculator, GCF Calculator, Exponent Calculator and Log Calculator cover factors, powers and logs. Students, teachers, engineers and analysts use them to check homework and quick figures. Every calculation runs in your browser, so the numbers you enter stay on your device.

• Percentage Calculator — Solve percentage problems: X% of Y, X is what % of Y, and percent change.
• Fraction Calculator — Add, subtract, multiply and divide fractions and simplify the result.
• Percent Error Calculator — Calculate percent error between an experimental and true value.
• Exponent Calculator — Raise a base to any power, including negative and fractional exponents.
• Log Calculator — Compute logarithms in any base, plus natural log and log base 10.
• Root Calculator — Find square roots, cube roots and any nth root of a number.
• Quadratic Formula Calculator — Solve quadratic equations ax²+bx+c=0 with real or complex roots and steps.
• Ratio Calculator — Simplify ratios and solve proportions for a missing value.
• Rounding Calculator — Round numbers to decimals, significant figures or the nearest multiple.
• Scientific Notation Converter — Convert numbers to and from scientific, e-notation and engineering notation.
• LCM Calculator — Find the least common multiple of two or more integers with the steps.
• GCF Calculator — Find the greatest common factor of two or more integers with the steps.
• Factor Calculator — List all factors of a number and its prime factorization.
• Triangle Calculator — Solve a triangle from sides and angles, with area, perimeter and type.
• Right Triangle Calculator — Solve a right triangle from any two sides or a side and an angle.
• Pythagorean Theorem Calculator — Find a missing side of a right triangle with a²+b²=c².
• Area Calculator — Calculate the area of circles, rectangles, triangles, trapezoids and more.
• Volume Calculator — Calculate the volume of spheres, cylinders, cones, boxes and more.
• Surface Area Calculator — Calculate the surface area of spheres, cylinders, cones, boxes and more.
• Circle Calculator — Find a circle’s radius, diameter, circumference and area from any one value.
• Standard Deviation Calculator — Calculate population and sample standard deviation, variance and mean of a data set.
• Mean, Median, Mode, Range Calculator — Find the mean, median, mode and range of a list of numbers.
• Statistics Calculator — Compute full descriptive statistics for a data set — mean, SD, quartiles and more.
• Probability Calculator — Calculate probabilities of single and combined events, including conditional.
• Permutation and Combination Calculator — Calculate permutations (nPr) and combinations (nCr) for n and r.
• Z-score Calculator — Convert a value to a z-score and find the probability from the normal distribution.
• Confidence Interval Calculator — Compute a confidence interval for a mean from sample statistics.
• Sample Size Calculator — Find the survey sample size needed for a confidence level and margin of error.
• Slope Calculator — Find the slope, intercept, distance and equation of a line through two points.
• Distance Calculator — Calculate the distance between two points in 2D or 3D space.
• Number Sequence Calculator — Find terms and sums of arithmetic, geometric and Fibonacci sequences.
• Half-Life Calculator — Solve half-life, decay time, and remaining quantity of a decaying substance.
• Big Number Calculator — Do exact arithmetic on very large integers beyond normal precision.
• Binary Calculator — Add, subtract, multiply and divide binary numbers and convert to decimal/hex.
• Hex Calculator — Add, subtract, multiply and divide hexadecimal numbers and convert bases.
• Matrix Calculator — Add, multiply, transpose and find the determinant and inverse of matrices.
• Scientific Calculator — A full scientific calculator for trig, logs, powers, roots and constants.
• Random Number Generator — Generate random numbers in a range, with unique values, decimals and count.

Guides

• How to Add, Subtract, Multiply and Divide Fractions — How to add fractions with a common denominator, subtract, multiply, divide and simplify them, and convert mixed numbers and decimals, with worked examples.
• Random Number Generators, Explained — How a random number generator works, how to pick a random number between 1 and 100, random numbers without repeats, modulo bias and real lottery odds.
• How to Calculate Standard Deviation — How to calculate standard deviation step by step, with a worked example, variance, sample vs population (n − 1 or n), the 68–95–99.7 rule and STDEV.S.
• How to Calculate Percentages — How to calculate percentage problems: X% of Y, what percent one number is of another, the percentage increase formula, reverse percentages and common mistakes.

Frequently asked questions

What can I calculate with these math calculators?

Percentages, fractions, ratios, rounding, exponents, logarithms, roots and scientific notation; factors, LCM and GCF; quadratic equations, slopes, number sequences and matrices; triangles, areas, volumes, surface areas, circles and the distance between points; and statistics from the mean and standard deviation to z-scores, confidence intervals, sample sizes, probabilities, permutations and combinations. There are also binary, hex and big-integer calculators, a half-life solver, a percent error calculator and a random number generator. For anything else, the Scientific Calculator evaluates typed expressions with trig functions, logs, powers, roots and factorials.

How do I calculate a percentage or a percent change?

The Percentage Calculator has three modes: X% of Y (15% of 240 is 36), X is what percent of Y (30 is 12.5% of 240), and percent change, which divides the difference by the starting value (80 to 100 is a 25% increase). Each answer comes with a worked line showing the calculation. To compare a measured value with a true one, use the Percent Error Calculator.

Do these math calculators show the steps?

Many do. The Quadratic Formula Calculator shows the discriminant and vertex, the Standard Deviation Calculator lists each value's deviation and squared deviation, the LCM Calculator and GCF Calculator break every number into prime factors, and the Percentage Calculator writes out the calculation. Others, such as the Triangle Calculator and Statistics Calculator, report every derived value (missing sides and angles, area and perimeter, or quartiles and skewness) so you can check your own working.

Are the numbers I type sent anywhere?

No. Every math calculator runs in your browser, so equations, data sets and matrices are computed on your device and are not uploaded to ArrayKit. The Random Number Generator also draws its numbers locally, from your browser's cryptographic random source.

How precise are the results?

Most calculators use standard double-precision arithmetic, which keeps about 15 significant digits, and round the display to a readable length. For exact answers with very long integers, use the Big Number Calculator; the Binary Calculator and Hex Calculator also use exact integer math. Statistical tools follow textbook definitions: the Standard Deviation Calculator shows both population and sample values, and the Confidence Interval Calculator uses the z-interval formula, so for small samples a t-interval will be somewhat wider.