About UnitGenie

UnitGenie is a free website with 93 unit converters and 115 calculators. Every tool shows the formula it uses and a worked example, so you can check the answer and not just take it on trust.

Our mission

Our mission is to make everyday calculations quick, clear and reliable. Whether you are pricing a concrete pour, counting business days to a deadline, sizing a resistor or converting units for homework, the answer should be one page away and easy to verify.

How accuracy is checked

Unit factors use exact international definitions, such as 1 inch = 25.4 mm and 1 pound = 0.45359237 kg.
Each calculator is tested against independent reference values: published tables, standards and textbook examples. The site cannot be published if a test fails.
Fractions, rounding and large whole numbers are computed with exact arithmetic, which avoids the small errors of ordinary floating point math.
Where a result depends on an assumption, such as the density of gravel, the assumption is stated on the page and can be changed.

What you will find

Construction and Home calculators: Square footage, concrete, gravel, stairs, fencing, drywall, roofing and pool volume.
Date and Time calculators: Days between dates, business days, age, time cards, military time and Unix timestamps.
Electrical calculators: Ohm's law, resistor color codes, voltage drop, watts to amps and battery life.
Fitness and Running calculators: One rep max, pace, heart rate zones, VO2 max, FFMI and powerlifting scores.
Grades and GPA calculators: Weighted grades, final exam targets, GPA and test scores.
Text, Code and Network calculators: Morse code, binary, hex, Base64, ciphers, subnet masks and file permissions.
Percent and Business Math calculators: Percentages, percent change, discounts, profit margin, break-even and tips.
Math and Statistics calculators: Ratios, fractions, averages, factors, rounding, quadratics and probability.
Geometry calculators: Area, volume and surface area of circles, triangles, cylinders, spheres and more.
Auto, Sports and Everyday calculators: Gear ratios, tire sizes, sleep cycles, gestation dates, sports stats and game settings.
Unit converters for length, weight, temperature, pressure, energy, data and many scientific quantities, with interactive visualizations.

Privacy

All calculations run in your browser. The numbers you enter are not sent to a server. See the privacy policy for details.

Contact us

We value corrections and suggestions. If you find a mistake or want a calculator added, write to [email protected].