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Free Online Calculators

Use free online calculators for quick math, percentages, fractions, powers, roots, statistics, geometry, and everyday estimates. Start with the basic calculator when you need a large, simple keypad, then jump to a focused calculator when the job needs a formula.

Find the right calculator faster

Pick the path that matches the question you are trying to answer. It is faster than opening a giant list and guessing which page fits.

I just need a calculatorUse the basic calculator for quick arithmetic, decimals, and everyday keypad work.I need a percent answerUse the percentage calculator for discounts, tips, percent change, and markups.I need fraction helpCalculate, simplify, compare, or convert fractions, mixed numbers, whole numbers, and decimals.I need electrical unit mathConvert watts, volts, phase, and power factor into an amps estimate before reading the electrical safety limits.I am planning moneyStart with mortgage estimates, then browse finance calculators for more planning tools.
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Popular calculator paths

These links match the main ways people search for free calculators: simple everyday math, percentage problems, scientific functions, money estimates, health estimates, and unit conversion.

Start by task

Basic CalculatorLarge simple calculator for everyday addition, subtraction, multiplication, division, decimals, and percent checks.Percentage CalculatorPercent of a number, percent change, discounts, markups, and reverse percentage questions.Scientific CalculatorTrig, logarithms, powers, roots, constants, and degree/radian mode for heavier math.Finance CalculatorsMortgage, loan, salary, interest, retirement, tax, and investment planning estimates.Health & Fitness CalculatorsBMI, calories, pregnancy, nutrition, pace, body measurement, and educational health estimates.Conversion CalculatorCommon unit conversions when a calculator answer needs a different measurement unit.

Useful calculator shortcuts

Open these calculators when you need dates, fractions, geometry, matrices, or exact large-number work without hunting through the full library.

Useful shortcuts

Date CalculatorAdd days, subtract days, and count calendar differences without mixing start and end dates.Fraction CalculatorCalculate, simplify, compare, and convert fractions, mixed numbers, whole numbers, and decimals with visible steps.Area CalculatorFind common shape areas and compare formulas before trusting a measurement.Matrix CalculatorAdd, multiply, transpose, and check determinant-style matrix work in the browser.Triangle CalculatorSolve triangle sides, angles, perimeter, and area while checking impossible inputs.Big Number CalculatorHandle very large whole-number math when normal calculator precision is not enough.

What this category helps with

  • Free online calculator pages for quick math checks, school work, percentage problems, fractions, powers, roots, and number theory.
  • A simple basic calculator path for visitors who want a large browser keypad with no signup and no app install.
  • Formula-based calculators that show enough context to understand the answer, not just copy it.
  • Related blog guides that explain common mistakes, practical examples, and when to use a more specific calculator.

Start with these tools

Basic CalculatorA clean browser calculator for quick arithmetic, percent checks, and copied results.Percentage CalculatorFind percent-of answers, percent change, discounts, and original values with reverse percentages.Ratio CalculatorSimplify ratios, scale matching ratios, and split totals by ratio parts.Percent Error CalculatorCompare your measured value with the accepted value, then see percent error and direction.Half-Life CalculatorCalculate remaining amount, elapsed time, or half-life with decay steps.Exponent CalculatorCalculate powers, zero and negative exponents, simple fraction exponents, and scientific notation.

All calculators

Open a tool, try the examples, then use the matching guide when you need more explanation.

Basic CalculatorA clean browser calculator for quick arithmetic, percent checks, and copied results.
Percentage CalculatorFind percent-of answers, percent change, discounts, and original values with reverse percentages.
Ratio CalculatorSimplify ratios, scale matching ratios, and split totals by ratio parts.
Half-Life CalculatorCalculate remaining amount, elapsed time, or half-life with decay steps.
Exponent CalculatorCalculate powers, zero and negative exponents, simple fraction exponents, and scientific notation.
Log CalculatorCalculate logarithms with custom bases, ln, log10, exponent checks, and change-of-base steps.
Root CalculatorCalculate square roots, cube roots, nth roots, exponent form, real-number rules.
Hex CalculatorAdd, subtract, multiply, divide, and convert hex numbers, then check decimal and binary output.
Scientific CalculatorA free scientific calculator for trig, inverse trig, logs, roots, powers, constants, and DEG/RAD mode.
Fraction CalculatorCalculate, simplify, compare, and convert fractions, mixed numbers, whole numbers, and decimals with steps.
Factor CalculatorList factors, factor pairs, and prime factorization for a whole number.
Rounding CalculatorRound decimals, significant figures, and place values using clear method steps.
Matrix CalculatorAdd, subtract, multiply, transpose, and find determinants for 2x2 and 3x3 matrices.
Big Number CalculatorAdd, subtract, multiply, and divide very large whole numbers exactly, then copy grouped or raw results and verify division remainders.
Number Sequence CalculatorGenerate arithmetic, geometric, and Fibonacci-style sequences with formulas, next terms, and copyable results.
Sample Size CalculatorEstimate survey sample size from confidence level, margin of error, and proportion.
Probability CalculatorCalculate P(A or B), P(A and B), complements, and independent-event probability checks.
Statistics CalculatorCalculate count, sum, mean, median, mode, range, quartiles, IQR, variance, and sample or population standard deviation.
Triangle CalculatorCheck three triangle sides, find a possible third-side range, or calculate SSS area, perimeter, angles, and type.
Volume CalculatorFind cubic volume for boxes, cubes, cylinders, spheres, and cones.
Slope CalculatorFind slope, rise, run, and a line equation from two points.
Area CalculatorCalculate flat-shape area for rectangles, triangles, circles, trapezoids, and parallelograms.
Distance CalculatorStraight-line distance between two 2D points, plus distance squared, deltas, midpoint, and formula steps.
Circle CalculatorFind radius, diameter, circumference, and area from one circle measurement.
Right Triangle CalculatorSolve a right triangle from two sides, including the missing side, area, perimeter, and acute angles.
Average CalculatorFind the average (arithmetic mean) of a number list, then compare median, mode, range, sum, and count.
P-value CalculatorEstimate left-tailed, right-tailed, or two-tailed standard-normal p-values from a z-score.
Mass CalculatorCalculate mass from density and volume with unit-matching reminders.
Weight CalculatorCalculate physics weight force from mass and gravity in newtons and pounds-force.
Speed CalculatorCalculate average speed from distance and time in mph, km/h, and m/s.
Watts to Amps CalculatorConvert watts to amps at common 12 V, 120 V, and 240 V inputs with AC, DC, three-phase, and power-factor options.
Stair CalculatorEstimate risers, treads, stair run, and angle from total rise and tread depth.
Resistor CalculatorDecode 4-band resistor color codes into ohms, tolerance, minimum, and maximum values.
Ohm's Law CalculatorSolve voltage, current, resistance, and power from two known circuit values.

Guides for this category

Each guide uses its matching tool, with example numbers and plain limits.