Common math tasks
Find a part of a whole when the rate and base are known.
Open calculator Fraction CalculatorAdd, subtract, multiply or divide fractions with a reduced result.
Open calculator Standard Deviation CalculatorSummarize spread while distinguishing a sample from a population.
Open calculator Right Triangle CalculatorSolve sides and angles using right-triangle relationships.
Open calculatorHow to use these calculators
Math calculators are most useful when they make the operation visible. A percentage question, a fraction operation and a standard-deviation problem can contain the same numbers but require different definitions. Start by naming the quantity you need, then choose the calculator whose inputs and output match that definition.
HitEquals keeps the equation beside the result so you can check signs, order of operations, rounding and domain restrictions. For schoolwork, reproduce the result by hand before submitting it. For work or research, retain the unrounded inputs and report only the precision justified by the original measurements.
Three checks that change the answer
Choose the right comparison
Use percentage change when one value is the baseline. Use percent difference when neither value is the original.
Define the data set
Statistics formulas change when observations are a sample rather than the entire population.
Keep precision honest
Carry extra digits during the calculation, then round once at the end to a useful number of places.
Before you use the answer
- Confirm every input uses the same scale or unit.
- Check whether negative values or zero are allowed.
- Read the displayed formula before copying the result.
- Test an easy value whose answer you can predict.
Browse all 44 math calculators
Every tool calculates in your browser. Pages marked “Reviewed guide” also include topic-specific explanations and source checks.
- Percentage CalculatorReviewed guideSolve the three everyday percentage questions: X% of Y, X as a percent of Y, and the whole when a part and its percent are known.
- Percentage Change CalculatorReviewed guideCompare an original value with a new value.
- Percent Difference CalculatorReviewed guideCompare two values without treating either one as the original.
- Scientific CalculatorReviewed guideEvaluate a mathematical expression with functions and visible precedence.
- Average CalculatorReviewed guideCalculate an arithmetic or weighted average with median, range and an auditable breakdown.
- Fraction CalculatorReviewed guideAdd, subtract, multiply or divide two fractions and reduce the answer to lowest terms.
- Ratio CalculatorReviewed guideSolve a proportion A : B = C : ?, simplify a ratio to lowest terms, or split a total in a given ratio.
- Grade CalculatorReviewed guideConvert earned and possible points into a percentage grade.
- GPA CalculatorReviewed guideCalculate semester and cumulative GPA from course credits and letter grades.
- Distance CalculatorReviewed guideFind the distance and midpoint between two points in 2D or 3D coordinates.
- Right Triangle CalculatorReviewed guideSolve a right triangle from one side and one acute angle, with the missing sides, angles, area and perimeter shown step by step.
- Percent Error CalculatorReviewed guideCompare an observed value with an accepted value using signed and absolute percent error.
- Long Division CalculatorReviewed guideDivide whole numbers and inspect every multiply, subtract and bring-down step.
- Pythagorean Theorem CalculatorReviewed guideFind a missing right-triangle side from the other two sides and inspect the Pythagorean substitution, squares and final root.
- Z Score CalculatorReviewed guideCalculate a z score from a value, mean and standard deviation, then interpret its direction and distance from the mean.
- Standard Deviation CalculatorReviewed guideCalculate sample or population variance and standard deviation from raw data.
- Volume CalculatorReviewed guideCalculate volume and surface area for five common three-dimensional shapes.
- Circle CalculatorReviewed guideSolve radius, diameter, circumference and area from any one circle measurement.
- Triangle CalculatorReviewed guideSolve a triangle from three sides, two sides and an included angle, or two angles and one side.
- Quadratic Formula CalculatorReviewed guideSolve real or complex roots and inspect the discriminant, vertex and axis of symmetry.
- Mean, Median, Mode and Range CalculatorReviewed guideCalculate central tendency, range, quartiles and a sorted frequency table from a numeric data set.
- Number Sequence CalculatorReviewed guideGenerate arithmetic, geometric or Fibonacci terms and calculate the requested term and finite sum.
- Exponent CalculatorReviewed guideSolve a power, exponent or positive real base from the other two values.
- Binary CalculatorReviewed guideAdd, subtract, multiply or divide binary integers and convert between binary, decimal and hexadecimal.
- Hex CalculatorReviewed guidePerform exact hexadecimal integer arithmetic and convert among hexadecimal, decimal and binary.
- Slope CalculatorReviewed guideFind slope, rise, run, angle and the line equation through two points.
- Log CalculatorReviewed guideCalculate a logarithm in any valid real base with common and natural-log comparisons.
- Probability CalculatorReviewed guideCalculate event probability, complements, repeated trials, or the union and intersection of independent events.
- Permutation and Combination CalculatorReviewed guideCalculate exact ordered arrangements and unordered selections, with or without repetition.
- Least Common Multiple CalculatorReviewed guideFind the exact least common multiple of up to 20 whole numbers and audit it through prime exponents.
- Greatest Common Factor CalculatorReviewed guideFind the greatest common factor of multiple integers with Euclidean steps and reduced ratios.
- Prime Factorization CalculatorReviewed guideDecompose a positive integer into its unique prime powers and list factor pairs.
- Rounding CalculatorReviewed guideRound to decimal places, significant figures or a chosen increment with an explicit tie rule.
- Sample Size CalculatorReviewed guideEstimate a proportion sample size from confidence, margin of error, expected proportion and finite population.
- Confidence Interval CalculatorReviewed guideCalculate a two-sided interval for a population mean or proportion with transparent assumptions.
- P-value CalculatorReviewed guideConvert a standard-normal z statistic into left-tailed, right-tailed or two-sided p-values.
- Root CalculatorReviewed guideCalculate real nth roots, principal square and cube roots, reciprocal exponent and verification.
- Matrix CalculatorReviewed guideAdd, subtract or multiply matrices and calculate determinant, transpose or inverse up to 5×5.
- Dice RollerReviewed guideRoll up to 100 virtual dice, add a modifier, inspect every result and share a reproducible seeded roll when needed.
- Random Number GeneratorReviewed guideGenerate one or many random integers within an inclusive range, with optional unique values and a reproducible seed.
- Factor CalculatorReviewed guideList every positive factor pair and divisor of a whole number.
- Scientific Notation CalculatorReviewed guideNormalize a decimal number into coefficient-times-power-of-ten notation with selected significant digits.
- Big Number CalculatorReviewed guideAdd, subtract, multiply, divide or find the remainder of signed integers beyond ordinary floating-point precision.
- Basic CalculatorReviewed guidePerform common two-number arithmetic with a visible operation and full-precision intermediate result.
Frequently asked questions
Which percentage calculator should I use?
Use percentage for a part of a base, percentage change for an old-to-new comparison and percent difference for two values with no baseline.
Why can my answer differ from a textbook?
The most common reasons are rounding, a different convention or entering a sample where a population was intended.
Should I round intermediate steps?
Usually no. Preserve full precision until the final result unless the method explicitly requires staged rounding.
Can a calculator prove that a method is appropriate?
No. It evaluates the chosen method; you still need to decide whether that method represents the problem.
Reference starting points
Individual reviewed guides cite the equation or standard used by that calculator. These authorities provide broader context for this collection.