Free Online Calculators
Quick, accurate calculators for the math that comes up in real life: working out a discount, splitting a bill, checking a percentage change or simplifying a fraction.
Every calculator shows the formula it used, so you can check the working instead of trusting a black box. Type your numbers and the answer updates as you go.
41 free tools · No sign-up · Works on phones and computers
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Popular calculators tools
- Percentage CalculatorFind X% of a number, or what percent one number is of another.
- Percentage Change CalculatorSee how much a value went up or down between two numbers, as a percent.
- Scientific CalculatorTrig, logs, powers, roots and brackets, with degrees or radians.
- Fraction CalculatorAdd, subtract, multiply and divide fractions and mixed numbers, simplified.
- Discount CalculatorSee the sale price and how much you save, including double discounts.
- Quadratic Equation SolverSolve ax² + bx + c = 0 with real or complex roots, the vertex and the discriminant.
All calculators tools
Grouped by what they help you do.
41 tools
- Percentage CalculatorPopularFind X% of a number, or what percent one number is of another.
- Percentage Change CalculatorPopularSee how much a value went up or down between two numbers, as a percent.
- Percentage Increase CalculatorAdd a percentage to a number — for price rises, raises and markups.
- Percentage Decrease CalculatorTake a percentage off a number — for discounts, cuts and reductions.
- Basic CalculatorA simple, clean calculator with keyboard support and history.
- Scientific CalculatorPopularTrig, logs, powers, roots and brackets, with degrees or radians.
- Fraction CalculatorPopularAdd, subtract, multiply and divide fractions and mixed numbers, simplified.
- Ratio CalculatorSimplify ratios and solve for the missing value in a proportion.
- Average CalculatorMean, median, mode and range of any list of numbers.
- Standard Deviation CalculatorSample and population standard deviation and variance, step by step.
- Square Root CalculatorSquare roots, cube roots and any nth root, with simplified radicals.
- Exponent CalculatorRaise any number to any power, including negative and decimal exponents.
- LCM & GCF CalculatorLeast common multiple and greatest common factor of two or more numbers.
- Prime Number CheckerCheck if a number is prime and see its prime factors.
- Discount CalculatorPopularSee the sale price and how much you save, including double discounts.
- Tip CalculatorWork out the tip and split the bill fairly between people.
- Unit Price CalculatorCompare products by price per unit to find the better deal.
- Fuel Cost CalculatorEstimate the fuel cost of a trip from distance, mileage and fuel price.
- Quadratic Equation SolverPopularSolve ax² + bx + c = 0 with real or complex roots, the vertex and the discriminant.
- Equation SolverSolve any equation in x, or a system of linear equations, with the answer checked.
- Derivative CalculatorDifferentiate a function step by step — first, second or third derivative.
- Matrix CalculatorAdd, multiply, transpose and invert matrices, and find the determinant.
- Vector CalculatorMagnitude, dot and cross products, angle and projection of 2D or 3D vectors.
- Logarithm CalculatorLog of any number in any base, natural log, log₁₀, log₂ and antilog.
- Factorial CalculatorExact n! for whole numbers up to 5,000, with digit count and trailing zeros.
- Permutation & Combination CalculatornPr and nCr, with or without repetition — exact even for big numbers.
- Probability CalculatorChance of one event, two events, or k successes in repeated trials.
- Sequence CalculatorThe nth term and sum of arithmetic and geometric sequences, with every term listed.
- Series (Sigma) CalculatorAdd up Σ f(n) between any limits, or the sum of an infinite geometric series.
- Fibonacci CalculatorAny Fibonacci number, exact, plus the sequence and the golden ratio.
- Z-Score CalculatorTurn a value into a z-score and percentile, or find probabilities under the normal curve.
- Confidence Interval CalculatorConfidence intervals for a mean or a proportion, with the margin of error.
- P-Value CalculatorP-values from z, t, chi-square or F statistics, with a plain-English verdict.
- Effect Size Calculator (Cohen's d)Cohen's d, Hedges' g and Glass's Δ for two groups, with an interpretation.
- Sample Size CalculatorHow many responses you need for a survey or study at your confidence level.
- Linear Regression CalculatorLine of best fit, correlation and R² from your x and y data, with predictions.
- Area CalculatorPopularArea and perimeter of squares, rectangles, triangles, circles, trapezoids and more.
- Circle CalculatorRadius, diameter, circumference and area of a circle from any one of them.
- Triangle CalculatorSolve a triangle from three sides, two sides and an angle, or two angles and a side.
- Volume & Surface Area CalculatorVolume and surface area of cubes, boxes, cylinders, spheres, cones and pyramids.
- Pythagorean Theorem CalculatorFind the hypotenuse or a missing leg of a right triangle, with the working.
Good to know
Which percentage calculator should I use?
Use the Percentage Calculator for questions like “what is 15% of 80?” or “30 is what percent of 120?”. Use the Percentage Change Calculator when you have an old and a new value and want to know how much it went up or down.
If you want to add or remove a percentage from a number — a price rise, a pay cut, a tax amount — the Percentage Increase and Percentage Decrease calculators give you the final number directly.
How accurate are these calculators?
They use standard formulas and double-precision arithmetic, the same number format spreadsheets use. Results are rounded only for display, and you can usually choose how many decimal places to show.
For very large or very precise numbers (more than about 15 significant digits) any browser-based calculator can show tiny rounding differences. For everyday use this never matters.
Calculators guides
Step-by-step help that goes with these tools.
Calculators tools: common questions
Are these calculators free?
Yes. Every calculator is free, needs no account and has no usage limit.
Do the calculators work offline?
Once a calculator page has loaded, the math runs in your browser, so it keeps working even if your connection drops.
Can I use them on my phone?
Yes. Every calculator is designed for small screens first, with large inputs and number keyboards on mobile.
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