Free Online Calculators
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Popular calculators
Date Difference
Days, weeks, and years between two dates.
Age Calculator
Your exact age in years, months, and days.
Days Until Date
Countdown to any future date.
Time Zone Converter
Convert times across world time zones.
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Browse by category
Date & Time
Days between dates, age, durations.
Conversion
Length, weight, temperature, area, speed, volume.
Math
Percentages, fractions, averages, standard deviation, ratios, GCF/LCM, exponents, square roots, quadratics and scientific notation.
Finance
Loans, interest, savings, and more.
Health
BMI, calories, body metrics, ovulation and macros.
Everyday
Tips, sleep, discounts, fuel, Roman numerals and a random number generator.
Geometry
Circle, rectangle, Pythagorean theorem, triangle area, cylinder and sphere.
Education
GPA, weighted course grade, final exam score needed and a quick test grader.
Coming soon
Cooking
Unit swaps and recipe scaling.
All calculators
Date & Time
- Date DifferenceDays, weeks, and years between two dates.
- Age CalculatorYour exact age in years, months, and days.
- Days Until DateCountdown to any future date.
- Time Zone ConverterConvert times across world time zones.
- Add / Subtract DateAdd or subtract days, weeks, months or years from a date.
- Business DaysWorking days (Mon–Fri) between two dates.
- Time DurationHours and minutes between two times.
- Week NumberISO 8601 week number for any date.
Conversion
- Length ConverterConvert between cm, inches, feet, meters and more.
- Weight ConverterConvert between kg, lb, oz, stone and more.
- Temperature ConverterConvert Celsius, Fahrenheit and Kelvin.
- Area ConverterConvert m², ft², acres, hectares and more.
- Speed ConverterConvert km/h, mph, m/s, knots and ft/s.
- Volume ConverterConvert mL, L, US cups, pints, quarts and gallons.
Math
- Percentage CalculatorPercent of, what percent, and percent change.
- Fraction CalculatorAdd, subtract, multiply or divide two fractions.
- Average CalculatorMean, median, mode, range, sum and count.
- Standard DeviationSample and population standard deviation and variance.
- Ratio CalculatorSimplify ratios and solve proportions A : B = C : D.
- GCF & LCMGreatest common factor and least common multiple of two or more numbers.
- Exponent CalculatorRaise any base to any power — positive, negative, zero or fractional exponents.
- Square Root CalculatorFind the square root of any number as a decimal and in simplified radical form, plus cube roots and other nth roots.
- Quadratic Formula CalculatorSolve ax² + bx + c = 0 with the discriminant and real or complex roots.
- Scientific Notation ConverterConvert decimals to scientific notation and back, with E-notation too.
Finance
- Loan Payment CalculatorMonthly payment, total interest and total cost of a loan.
- Compound InterestGrow savings with daily, monthly, quarterly or yearly compounding.
- Simple InterestInterest and final balance using the simple-interest formula.
- Savings CalculatorFuture value of an initial deposit plus monthly contributions.
- Mortgage CalculatorMonthly mortgage payment with property tax and home insurance.
- Auto Loan CalculatorCar payment with sales tax, trade-in and down payment.
Health
- BMI CalculatorBody Mass Index from weight and height (metric or imperial).
- BMR CalculatorBasal Metabolic Rate using the Mifflin-St Jeor equation.
- Calorie CalculatorDaily calories (TDEE) for maintain, lose or gain weight.
- Body Fat CalculatorBody fat percentage using the U.S. Navy circumference method.
- Ideal Weight CalculatorDevine, Robinson, Miller and Hamwi ideal-weight estimates.
- Due Date CalculatorEstimated pregnancy due date using Naegele's rule.
- Ovulation CalculatorEstimate ovulation, fertile window and next period from your last period date and cycle length.
- Macro CalculatorDaily calories and macros (40/30/30 carbs, protein, fat) from your stats, activity and goal.
Everyday
- Tip CalculatorWork out the tip, total bill, and split per person.
- Sleep CalculatorFind the best bedtime or wake-up time based on sleep cycles.
- Discount CalculatorSale price after a percentage off and how much you save.
- Fuel Cost CalculatorTrip fuel needed and total cost in US or metric units.
- Roman Numeral ConverterConvert numbers to Roman numerals and back (1–3999).
- Random Number GeneratorPick random numbers between any min and max, with optional unique (no repeats) mode.
Geometry
- Circle CalculatorDiameter, circumference and area from the radius.
- Pythagorean TheoremFind the hypotenuse or a missing leg of a right triangle.
- Triangle Area CalculatorArea from base and height, or from three sides with Heron's formula.
- Rectangle CalculatorArea, perimeter and diagonal from length and width.
- Cylinder CalculatorVolume and total surface area from radius and height.
- Sphere CalculatorVolume and surface area from the radius.
Education
- GPA CalculatorCompute your grade point average on the standard 4.0 scale.
- Grade CalculatorCombine scores and weights into your overall course grade.
- Final Grade CalculatorThe score you need on the final to reach your target grade.
- Test Grade CalculatorQuick EZ grader: percentage and letter from correct / total.