Length & Distance Unit Converter

The US Customary and Metric Measurement Systems

Around the world, two primary systems of measurement dictate how distance and length are recorded: the US Customary System (derived from historic British Imperial units) and the International System of Units (SI / Metric).

While the United States primarily utilizes inches, feet, yards, and miles in everyday life, construction, speed limits, and retail commerce, science, medicine, and international trade rely entirely on metric millimeters, centimeters, meters, and kilometers.

The International Yard and Pound Agreement of 1959

Prior to 1959, the United States, the United Kingdom, Canada, Australia, and New Zealand had slight mathematical variations in their definitions of the inch. On July 1, 1959, an international treaty unified these definitions worldwide:

Common Everyday Conversion Formulas

1. Converting Inches to Centimeters (in → cm)

To convert from inches to centimeters, multiply your inch value by 2.54:

Centimeters = Inches × 2.54
Example: A standard 12-inch ruler is: 12 × 2.54 = 30.48 cm.

2. Converting Centimeters to Inches (cm → in)

To convert centimeters into inches, divide your centimeter value by 2.54 (or multiply by approximately 0.393701):

Inches = Centimeters ÷ 2.54
Example: 10 centimeters equals: 10 ÷ 2.54 = 3.937 inches.

3. Converting Feet to Meters (ft → m)

To convert feet to meters, multiply by 0.3048:

Meters = Feet × 0.3048
Example: A 6-foot tall individual is: 6 × 0.3048 = 1.8288 meters (approx. 183 cm).

4. Converting Miles to Kilometers (mi → km)

To convert statutory miles to kilometers, multiply by 1.609344:

Kilometers = Miles × 1.609344
Example: A 60 mph highway speed is: 60 × 1.609344 ≈ 96.56 km/h.

Fractional Inch to Metric Conversion Master Chart

Frequently Asked Questions About Unit Conversion