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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 calculator Use the basic calculator for quick arithmetic, decimals, and everyday keypad work. I need a percent answer Use the percentage calculator for discounts, tips, percent change, and markups. I need fraction help Add, subtract, multiply, divide, simplify, or convert fractions and mixed numbers. I need electrical unit math Convert watts, volts, phase, and power factor into an amps estimate before reading the electrical safety limits. I am planning money Start 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.

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

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 Calculator A clean browser calculator for quick arithmetic, percent checks, and copied results. Percentage Calculator Find percent-of answers, percent change, discounts, markups, and reverse percentages. Ratio Calculator Simplify ratios, scale matching ratios, and split totals by ratio parts. Percent Error Calculator Compare your measured value with the accepted value, then see percent error and direction. Half-Life Calculator Calculate remaining amount, elapsed time, or half-life with decay steps. Exponent Calculator Calculate powers with positive, negative, zero, decimal, and fraction exponents.

All calculators

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

Basic Calculator A clean browser calculator for quick arithmetic, percent checks, and copied results. Open Percentage Calculator Find percent-of answers, percent change, discounts, markups, and reverse percentages. Open Ratio Calculator Simplify ratios, scale matching ratios, and split totals by ratio parts. Open Percent Error Calculator Compare your measured value with the accepted value, then see percent error and direction. Open Half-Life Calculator Calculate remaining amount, elapsed time, or half-life with decay steps. Open Exponent Calculator Calculate powers with positive, negative, zero, decimal, and fraction exponents. Open Log Calculator Calculate logarithms with custom bases, ln, log10, and change-of-base steps. Open Root Calculator Calculate square roots, cube roots, nth roots, exponent form, and steps. Open Quadratic Formula Calculator Solve ax^2 + bx + c = 0 with roots, discriminant, vertex, and steps. Open Binary Calculator Add, subtract, multiply, divide, and convert binary numbers. Open Hex Calculator Add, subtract, multiply, divide, and convert hexadecimal numbers. Open Kawaii Calculator A cute pastel calculator for quick everyday math. Open Scientific Calculator A free scientific calculator for trig, logs, roots, powers, and constants. Open Fraction Calculator Add, subtract, multiply, divide, and simplify fractions with steps. Open Least Common Multiple Calculator Find the least common multiple of two or more whole numbers with steps. Open Greatest Common Factor Calculator Find the greatest common factor of two or more whole numbers with steps. Open Factor Calculator List factors, factor pairs, and prime factorization for a whole number. Open Rounding Calculator Round numbers by decimal places, significant figures, or place value. Open Matrix Calculator Add, subtract, multiply, transpose, and find determinants for 2x2 and 3x3 matrices. Open Scientific Notation Calculator Convert numbers to scientific notation or back to standard form. Open Big Number Calculator Add, subtract, multiply, and divide very large whole numbers exactly, including division remainders. Open Standard Deviation Calculator Calculate sample or population standard deviation, variance, mean, and count. Open Number Sequence Calculator Generate arithmetic, geometric, and Fibonacci-style number sequences. Open Sample Size Calculator Estimate survey sample size from confidence level, margin of error, and proportion. Open Probability Calculator Calculate event union, intersection, complements, and independent-event probability. Open Statistics Calculator Calculate count, sum, mean, median, mode, range, quartiles, variance, and standard deviation. Open Mean, Median, Mode, Range Calculator Find the four headline descriptive statistics for a list of numbers. Open Permutation and Combination Calculator Calculate nPr and nCr for counting arrangements and selections. Open Z-score Calculator Calculate a z-score and approximate standard normal percentile. Open Confidence Interval Calculator Calculate z confidence intervals for a mean or a proportion. Open Triangle Calculator Find triangle area, perimeter, angles, and type from three side lengths. Open Volume Calculator Find cubic volume for boxes, cubes, cylinders, spheres, and cones. Open Slope Calculator Find slope, rise, run, and a line equation from two points. Open Area Calculator Calculate flat-shape area for rectangles, triangles, circles, trapezoids, and parallelograms. Open Distance Calculator Find distance, delta x, delta y, and midpoint from two coordinate points. Open Circle Calculator Find radius, diameter, circumference, and area from one circle measurement. Open Surface Area Calculator Calculate surface area for boxes, cubes, cylinders, spheres, and cones. Open Pythagorean Theorem Calculator Solve a missing right-triangle side with a^2 + b^2 = c^2. Open Right Triangle Calculator Solve right triangle sides, area, perimeter, and acute angles. Open Prime Factorization Calculator Break a whole number into prime factors and grouped prime powers. Open Long Division Calculator Divide whole numbers with quotient, remainder, decimal answer, and steps. Open Average Calculator Find the average of a list, plus count, sum, median, mode, and range. Open P-value Calculator Estimate left-tailed, right-tailed, or two-tailed p-values from a z-score. Open Square Footage Calculator Calculate square feet, square yards, and square meters from length, width, and quantity. Open Density Calculator Calculate density from mass and volume with a custom unit label. Open Mass Calculator Calculate mass from density and volume with unit-matching reminders. Open Weight Calculator Calculate physics weight force from mass and gravity in newtons and pounds-force. Open Speed Calculator Calculate average speed from distance and time in mph, km/h, and m/s. Open Voltage Drop Calculator Estimate voltage drop from current, wire length, voltage, phase, and copper AWG size. Open Watts to Amps Calculator Convert watts to amps with voltage, phase type, and power factor. Open Amps to Watts Calculator Convert amps to watts for DC, single-phase AC, and three-phase AC loads. Open Kilowatts to Amps Calculator Convert kilowatts to amps with voltage, phase, power factor, and efficiency. Open kVA to Amps Calculator Convert apparent power in kVA to amps for single-phase or three-phase systems. Open Amp Hours to Watt Hours Calculator Convert battery amp-hours and voltage into watt-hours and kilowatt-hours. Open Watt Hours to Amp Hours Calculator Convert battery watt-hours into amp-hours at a selected voltage. Open Wire Resistance Calculator Estimate copper wire resistance from AWG size, length, and conductor count. Open Wire Size Calculator Estimate a copper AWG size from current, length, voltage, phase, and voltage-drop target. Open Stair Calculator Estimate risers, treads, stair run, and angle from total rise and tread depth. Open Resistor Calculator Decode 4-band resistor color codes into ohms and tolerance range. Open Ohms Law Calculator Solve voltage, current, resistance, and power from two known circuit values. Open

Guides for this category

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