Math, dates & conversions calculators
Solve percentages and fractions, compare dates and convert compatible measurement units.
Before you begin
- Check whether a percentage is applied to the original value or a reduced value.
- Read the date inclusion rules before comparing day counts.
- Length, area, volume and mass are different unit families; volume-to-mass conversion also needs density.
Choose your calculator
Tip calculator
Calculate a tip, total bill and equal split per person using a rate you choose.
CalculatorBusiness Days Calculator
See business days (inclusive) and review calendar days and weekday holidays excluded using values you enter.
CalculatorWorking Days Calculator
See working days (inclusive) and review calendar days and holiday and leave days excluded using values you enter.
CalculatorDate Difference Calculator
See days between dates and review completed calendar years and remaining calendar months using values you enter.
CalculatorAge Calculator
See completed years of age and review days lived and days to next birthday using values you enter.
CalculatorHours Calculator
See paid hours and review paid minutes and elapsed minutes using values you enter.
CalculatorPercentage calculator
Find percentages, reverse a percentage, compare amounts and calculate increases or decreases.
CalculatorPercentage Increase Calculator
See percentage change and review absolute change and original value using values you enter.
CalculatorDiscount calculator
See the final price and amount saved after a percentage discount.
CalculatorFraction Calculator
Add, subtract, multiply and divide fractions, work with mixed numbers, simplify exact large fractions and convert decimals.
CalculatorUnit Conversion Calculator
See converted value (mi) and review original value (km) using values you enter.
CalculatorCooking Measurement Calculator
See converted recipe amount (ml) and review original amount (cup) and entered density (g / ml) using values you enter.
CalculatorScientific Calculator
Scientific: Real-number expressions with decimal arithmetic; explicit multiplication is required.
CalculatorBasic Calculator
Basic: Real-number expressions with decimal arithmetic; explicit multiplication is required.
CalculatorBig Number Calculator
Big Number: Real-number expressions with decimal arithmetic; explicit multiplication is required.
CalculatorExponent Calculator
Exponent: Real powers; a negative base with a non-integer exponent may have no real result..
CalculatorRoot Calculator
Root: Negative radicands require an odd integer root index..
CalculatorLog Calculator
Log: Positive argument and positive base other than 1..
CalculatorPercent Error Calculator
Percent Error: The reference value must be nonzero; also displays signed relative error..
CalculatorQuadratic Formula Calculator
Quadratic Formula: Solves quadratic equations, including complex roots and the linear a=0 case..
CalculatorLeast Common Multiple Calculator
Least Common Multiple: Positive integers only.
CalculatorGreatest Common Factor Calculator
Greatest Common Factor: Positive integers only.
CalculatorCommon Factor Calculator
Common Factor: Positive integers only.
CalculatorFactor Calculator
Factor: Positive integers only.
CalculatorPrime Factorization Calculator
Prime Factorization: Positive integers only.
CalculatorPermutation and Combination Calculator
Permutation and Combination: Distinct items; repetitions use n^r permutations and combinations with replacement..
CalculatorBinary Calculator
Binary: Signed integer arithmetic, up to 256 digits per operand.
CalculatorHex Calculator
Hex: Signed integer arithmetic, up to 256 digits per operand.
CalculatorRounding Calculator
Rounding: Supports positive and negative values and five explicit rounding conventions..
CalculatorScientific Notation Calculator
Scientific Notation: Decimal scientific notation, conversion and arithmetic; up to 30 significant digits..
CalculatorLong Division Calculator
Long Division: Exact integer quotient and remainder for nonnegative integers, plus a decimal expansion..
CalculatorStatistics Calculator
Statistics: Descriptive statistics for finite numeric data, with population or sample variance selected explicitly..
CalculatorStandard Deviation Calculator
Standard Deviation: Descriptive statistics for finite numeric data, with population or sample variance selected explicitly..
CalculatorMean, Median, Mode, Range Calculator
Mean, Median, Mode, Range: Descriptive statistics for finite numeric data, with population or sample variance selected explicitly..
CalculatorAverage Calculator
Average: Descriptive statistics for finite numeric data, with population or sample variance selected explicitly..
CalculatorNumber Sequence Calculator
Number Sequence: Generate terms and their sum from explicit sequence parameters..
CalculatorProbability Calculator
Probability: Explicit independent events or a supplied joint probability; conditional probabilities shown only when defined..
CalculatorZ-score Calculator
Z-score: Standardized score with a normal-distribution percentile estimate..
CalculatorSample Size Calculator
Sample Size: Normal approximation for a random-sample proportion; does not include design effects or nonresponse..
CalculatorConfidence Interval Calculator
Confidence Interval: Mean confidence interval with a known population standard deviation.
CalculatorP-value Calculator
P-value: Normal z, Student t, chi-square and F probabilities.
CalculatorHalf-Life Calculator
Half-Life: Exponential decay with constant half-life; no replenishment or background contribution..
CalculatorRatio Calculator
Ratio: Simplification requires whole numbers; proportions and splitting accept nonnegative decimals..
CalculatorMatrix Calculator
Matrix: Real matrices up to 10×10.
CalculatorDistance Calculator
Distance: Use one consistent length unit for all dimensions.
CalculatorSlope Calculator
Slope: Use one consistent length unit for all dimensions.
CalculatorCircle Calculator
Circle: Use one consistent length unit for all dimensions.
CalculatorPythagorean Theorem Calculator
Pythagorean Theorem: Use one consistent length unit for all dimensions.
CalculatorRight Triangle Calculator
Right Triangle: Use one consistent length unit for all dimensions.
CalculatorTriangle Calculator
Triangle: Use one consistent length unit for all dimensions.
CalculatorArea Calculator
Area: Use one consistent length unit for all dimensions.
CalculatorVolume Calculator
Volume: Use one consistent length unit for all dimensions.
CalculatorSurface Area Calculator
Surface Area: Use one consistent length unit for all dimensions.
CalculatorTime Calculator
Time: Elapsed durations, not local clock times; daylight saving and time zones do not apply.
CalculatorTime Duration Calculator
Time Duration: Calendar/clock arithmetic without daylight-saving adjustments.
CalculatorDay Counter
Day Counter: Calendar/clock arithmetic without daylight-saving adjustments.
CalculatorDate Calculator
Date: Gregorian calendar in years 0001–9999, using UTC dates to avoid daylight-saving shifts.
CalculatorDay of the Week Calculator
Day of the Week: Gregorian calendar; ISO weeks begin on Monday and week 1 contains January 4..
CalculatorTime Card Calculator
Time Card: Editable work-period estimate, up to 31 shifts.
CalculatorTime Zone Calculator
Time Zone: Uses the device's IANA time-zone data, including daylight saving where available.
CalculatorRoman Numeral Converter
Roman Numeral Converter: Supports canonical Roman numerals for integers 1–3999.
CalculatorSleep Schedule Calculator
Sleep Schedule: Scheduling illustration only.
CalculatorName Compatibility Game
Name Compatibility Game: Entertainment only.
CalculatorGDP Calculator
GDP: Expenditure-method accounting using entered totals in one currency and period.
CalculatorMileage Reimbursement Calculator
Mileage Reimbursement: Uses your entered employer or jurisdiction rate.
CalculatorRandom Number Generator
Random Number Generator: Generate values on demand.
CalculatorDice Roller
Dice Roller: Uses platform cryptographic randomness with rejection sampling.
CalculatorPassword Generator
Password Generator: Passwords are generated locally on demand and are not saved by this tool.
Understand the calculation
How to calculate two successive discounts
Calculate stacked discounts correctly and understand why 20% off followed by 10% off is a total discount of 28%, not 30%.
guideCups to grams: why the ingredient matters
Learn why cups cannot convert directly to grams without density, distinguish US and metric cups, and calculate a sample ingredient mass.
guideSI prefixes and scientific notation explained
Read all 24 SI prefixes, distinguish uppercase and lowercase symbols, and convert decimal powers without confusing a measurement with its unit.
conversionMillimeters to centimeters converter
Convert millimeters to centimeters with an editable calculator, worked example, formula and reference table. Check the unit definitions before you convert.
conversionMillimeters to meters converter
Convert millimeters to meters with an editable calculator, worked example, formula and reference table. Check the unit definitions before you convert.
conversionMillimeters to kilometers converter
Convert millimeters to kilometers with an editable calculator, worked example, formula and reference table. Check the unit definitions before you convert.