Unit Converters
Convert between metric and US customary units for length, weight, temperature, volume, area and speed. Every converter uses the exact legal definition of its units, such as 1 inch = 2.54 cm, 1 pound = 0.45359237 kg and 1 US gallon = 3.785411784 L. It rounds only the number you see, so results don't pick up float noise like 0.30000000000000004.
Each page converts both ways as you type and gives you a shareable link for any value. You'll also find the formula with a worked example, a printable conversion chart, everyday reference points and notes on where US, UK imperial and metric measures differ.
Length & distance
Metric and US customary lengths, from millimeter drill bits to kilometer race distances. Every factor rests on the 1959 definition of the inch as exactly 2.54 cm.
- Centimeters to Inches (cm to in)in = cm ÷ 2.54
- Inches to Centimeters (in to cm)cm = in × 2.54
- Kilometers to Miles (km to mi)mi = km ÷ 1.609344
- Miles to Kilometers (mi to km)km = mi × 1.609344
- Meters to Feet (m to ft)ft = m ÷ 0.3048
- Feet to Meters (ft to m)m = ft × 0.3048
- Millimeters to Inches (mm to in)in = mm ÷ 25.4
- Inches to Millimeters (in to mm)mm = in × 25.4
Weight & mass
Kilograms, grams, pounds, ounces and stone. The pound is defined as exactly 0.45359237 kg, and the stone is 14 pounds.
Temperature
Celsius and Fahrenheit don't share a zero, so these conversions use an offset as well as a multiplier. You can't just scale the number.
Volume & cooking
Milliliters, liters, US fluid ounces, cups and gallons, with notes on where US, imperial (UK) and metric measures differ.
- Milliliters to Fluid Ounces (mL to oz)fl oz = mL ÷ 29.5735295625
- Fluid Ounces to Milliliters (oz to mL)mL = fl oz × 29.5735295625
- Liters to Gallons (L to gal)gal = L ÷ 3.785411784
- Gallons to Liters (gal to L)L = gal × 3.785411784
- Cups to Milliliters (cups to mL)mL = cup × 236.5882365
- Milliliters to Cups (mL to cups)cup = mL ÷ 236.5882365
Area & land
Square feet, square meters, acres and hectares for floor plans, lots and farmland. Area factors are the length factor squared.
- Square Feet to Square Meters (sq ft to m²)m² = sq ft × 0.09290304
- Square Meters to Square Feet (m² to sq ft)sq ft = m² ÷ 0.09290304
- Acres to Square Feet (acres to sq ft)sq ft = ac × 43560
- Square Feet to Acres (sq ft to acres)ac = sq ft ÷ 43560
- Hectares to Acres (ha to acres)ac = ha ÷ 0.40468564224
- Acres to Hectares (acres to ha)ha = ac × 0.40468564224
Speed
Miles per hour and kilometers per hour for road signs, speedometers and running or cycling paces.