Length Converter

A length converter translates a measurement between units like meters, feet, inches, miles, kilometers, yards, centimeters, and millimeters. The metric system (mm, cm, m, km) uses powers of 10, so converting within metric is just moving the decimal. The imperial system (in, ft, yd, mile) uses uneven ratios (12 inches/foot, 3 feet/yard, 5,280 feet/mile) that require actual math.

This converter handles all the common units at once — enter one value and see conversions to every other unit instantly. Useful for cross-system work (US ↔ rest of world), DIY projects, travel, and homework.

Travel: A road sign in Europe says 90 km/h. Speed limit in mph?

• 90 km × (1 mile / 1.609 km) = ~56 mph

DIY: Bookshelf design calls for 6 feet of board. How many cm?

• 6 ft × 0.3048 m × 100 = 182.88 cm

Running: A 5K race. How many miles?

• 5 km × (1 mile / 1.609 km) = 3.107 miles

Estimation: 100 yards (US football field). How many meters?

• 100 × 0.9144 = 91.44 m (almost the same as a 100m sprint track)

• International travel — converting speed limits and distances.
• DIY and home improvement — switching between metric tools and imperial product specs.
• Sports — comparing 100 m sprint to 100 yard dash, or marathon distance to miles.
• Online shopping — translating dimensions on international product listings.
• Science homework — moving between SI and other measurement systems.

• Confusing yards with meters. They're close (1 yd = 0.91 m) but not equal — a 100m and 100yd sprint are 8.6 m apart.
• Inch vs. foot ambiguity. 5'10" means 5 feet 10 inches, not 5.10 feet. Convert to either pure feet (5.83 ft) or all inches (70 in) before doing math.
• Forgetting cm vs. mm. 1 cm = 10 mm — easy to mistake when reading rulers.
• Mixing nautical and statute miles. A flight distance in nautical miles is 15% longer than the same number of statute miles.
• Estimating with wrong rounding. 1 m ≈ 3.3 ft is fine for rough estimates; for engineering tolerance, use 1 m = 3.281 ft.