Length Converter

Use our free length converter to switch between the length units used every day on a job site — feet, inches, yards, meters, centimeters, and millimeters. Enter a single value and see it converted to all six units at once, which is faster than hunting down a conversion chart mid-measurement. It's built for contractors, estimators, and DIYers who need a quick, accurate conversion without doing the math by hand.

How to use this calculator.

1. Enter your value. Type the length you want to convert into the input field above. The default unit is feet.
2. Confirm the unit. Make sure the number you entered actually matches the unit labeled next to the input field.
3. Read the results. All six converted values — feet, inches, meters, centimeters, millimeters, and yards — update instantly below.
4. Cross-check with a second value. If you already know the length in a different unit, enter that separately to confirm your conversion lines up.
5. Round to the precision you need. Construction typically works to 1/8 inch or 1 mm; drop the extra decimal places once you've confirmed the number.

How do you calculate length conversions?

This calculator treats feet as the base unit and multiplies or divides by a fixed conversion factor to reach each target unit.

Inches = Feet × 12

Meters = Feet × 0.3048

Centimeters = Feet × 30.48

Millimeters = Feet × 304.8

Yards = Feet ÷ 3

Where:

• Feet: The value you enter, in feet.
• 12, 0.3048, 30.48, 304.8: Fixed, internationally standardized conversion factors between feet and each target unit.
• 3: The number of feet in one yard.

Example calculation.

Convert 18 feet into all other common length units.

1. Feet to inches: 18 × 12 = 216 in
2. Feet to meters: 18 × 0.3048 = 5.49 m
3. Feet to centimeters: 18 × 30.48 = 548.64 cm
4. Feet to millimeters: 18 × 304.8 = 5,486.4 mm
5. Feet to yards: 18 ÷ 3 = 6 yd

Result: 18 ft equals 216 in, 5.49 m, 548.64 cm, 5,486.4 mm, and 6 yd.

Tips from the field.

• Know your precision needs. Construction typically needs 1/8-inch precision (0.125 in), while engineering layouts may require thousandths. Round to the precision your project demands, not the precision the calculator gives you.
• Watch for mixed units. A measurement like "5 ft 6 in" has to be converted to a single unit before you run it through a calculator. Convert the inches to decimal feet (6 ÷ 12 = 0.5 ft) and add it to the feet value (5.5 ft total).
• Survey feet vs. international feet. The U.S. survey foot differs from the international foot by about 2 parts per million. For almost all construction work this is negligible, but on large-scale surveying jobs, confirm which standard your source data uses.
• Standardize before you order. If a plan mixes metric and imperial dimensions, convert everything to one system before calculating material quantities. Mixing units mid-calculation is one of the most common causes of ordering errors.

Disclaimer: Conversions use standard international conversion factors. For critical engineering or surveying applications, verify conversions against certified reference standards. Rounding errors can accumulate in multi-step conversions.