Practical measurement guide
Metric vs Imperial Units
Compare metric and imperial length units, including centimeters, meters, inches, feet, yards, and miles.
Metric units use powers of ten, while imperial length units include inches, feet, yards, and miles.
in
Decimals and fractions work, for example 1.5, 1/2, or 1 1/2.
cm
Fractions
1 in = 2.54 cm
1 in × 2.54 = 2.54 cm
Decimal inches1 in
Feet + inches0 ft 1 in
Nearest 1/16 inch1"
The practical difference
Metric length units use powers of ten, such as millimeters, centimeters, meters, and kilometers. Imperial length units include inches, feet, yards, and miles, which are still common in US product sizes, height, and screen diagonals.
Common length relationships
One inch equals exactly 2.54 cm. One foot equals 12 inches, or 30.48 cm. For everyday size checks, convert the original measurement first, then round only the displayed result.
Related measurement tools
Frequently asked questions
Is cm metric or imperial?
Centimeters are metric units.
Is inch metric or imperial?
Inches are imperial units, and 1 inch equals exactly 2.54 centimeters.