Unit Converters

Weight Converter

Convert weight between kilograms, pounds, ounces, grams, milligrams, metric tons, and stone. NIST-exact conversion factors.

Temperature Converter

Convert temperature between Celsius, Fahrenheit, Kelvin, and Rankine. Instant, accurate temperature unit converter.

Length Converter

Convert length between 9 units: millimeters, centimeters, meters, kilometers, inches, feet, yards, miles, and nautical miles. NIST-exact.

Speed Converter

Convert speed between mph, km/h, m/s, knots, and feet per second. Instant speed unit converter with all common units.

Volume Converter

Convert volume between liters, milliliters, gallons, quarts, pints, cups, fluid ounces, and cubic meters. Metric and imperial.

Fuel Cost & Gas Mileage Calculator

Calculate gas mileage (MPG, km/L, L/100km) from your trip distance and fuel used, or estimate total fuel cost from distance, efficiency, and fuel price.

Recipe Converter & Scaler

Scale a recipe up or down for any number of servings, or convert common baking ingredients between cups, tablespoons, teaspoons, grams, and ounces.

Tire Size & Speedometer Error Calculator

Enter a tire size code to get diameter, circumference, and revolutions per mile, or compare two sizes to see the speedometer and odometer error after a tire swap. Free, instant.

Digital Storage Unit Converter

Convert between digital storage units — bits, bytes, KB/MB/GB/TB/PB (decimal) and KiB/MiB/GiB/TiB/PiB (binary). See why your 1TB drive shows as 931GB.

Download & Upload Time Calculator

Estimate how long a file transfer will take from file size and connection speed, or back-solve the speed needed to hit a target time. Free, instant, no upload.

Knitting Needle & Crochet Hook Size Converter

Convert knitting needle and crochet hook sizes between US, UK/Canadian, and metric (mm), plus a yarn-weight-to-size reference chart. Free, instant, no sign-up.

Yarn Amount (Yardage) Calculator

Estimate how much yarn you need for a knitting or crochet project by project type, size, and yarn weight. Get total yardage, meters, and skeins. Free, instant.

Screw, Bolt & Fastener Size Converter

Convert screw and bolt sizes between metric (M), UNC, UNF, and wood/sheet-metal screw gauge, with the nearest equivalent and tap drill size. Free, instant.

ND Filter / Long Exposure Time Calculator

Enter your metered shutter speed and ND filter strength (stops, filter factor, or ND2–ND100000) to get the correct long-exposure shutter speed instantly, with a bulb-mode warning.