Length Converter

What this converter is for — and what it is not

Length is the unit family with the most historical baggage: feet, inches and miles sitting beside millimetres, metres and kilometres, all still in daily use. This tool covers everyday conversions — travel distances, room furniture sizes, hardware shopping, drawings sent abroad — with exact factors, not rounded approximations, and it shows up six decimals so you can spot whether a figure was rounded earlier.

Use a different tool when the dimension is not a line. Areas (paint, flooring, plots) belong to the Area Converter or the Square Footage Calculator, since area scales as length squared and a "feet to metres" shortcut gives badly wrong results. Height measured in feet-and-inches needs combining first: 5 ft 10 in is 70 inches, not 5.10 of anything.

A worked example, step by step

Problem: a US product page states a shelf is 55 inches long. How long is it in centimetres?

1. An inch is exactly 2.54 cm by international agreement — no estimate needed.
2. Multiply: 55 × 2.54 = 139.7.
3. Convert to metres for furniture talk: 139.7 cm = 1.397 m.
4. Sense-check: 55 inches is a little over 4 and a half feet, and 140 cm is a plausible shelf length. It passes.

The multiplication is exact, which is the norm here: the conversion factors for length are defined, not measured, so any two exact-value tools must agree digit for digit.

Reference conversions

Memorise two of these — the inch and the mile — and most travel and shopping conversions become one-step mental arithmetic.

Mistakes that cause real-world errors

• Reading 5.10 ft as five feet ten inches. It is five point one zero feet — about 5 ft 1 in. Convert inches to whole digits first.
• Swapping nautical and statute miles. A nautical mile is 1.852 km, about 15% longer; it belongs to sea and air navigation, not road signs.
• Squaring a length to get area. 10 ft × 10 ft is not "20 ft"; it is 100 ft², and mixing this up wrecks paint and flooring estimates.
• Rounding at an intermediate step. 0.3048 rounded to 0.3 loses 1.6% immediately; keep the real factor until the end.
• Trusting furniture photos. Product pages quote dimensions in the seller's local units; run the conversion before buying anything that must fit.

Keep exploring

• Area Converter — flat dimensions in m², hectares and acres.
• Square Footage Calculator — rectangle area with a price per square metre.
• Speed Converter — the same mile-to-kilometre logic applied to pace.
• Guide: Unit Conversion Mistakes to Avoid.