Length Converter
Length measures distance along a single dimension: how far apart two points are, or how long, wide, tall, or deep something is. It is one of the most common everyday measurements, used for everything from a recipe ingredient cut to centimeters to the distance between two cities.
Popular Length Conversions
All Length Conversions
People convert length units mainly because the world uses two systems side by side. Most countries use the metric system (millimeters, centimeters, meters, kilometers), while the United States and a few others still rely on imperial and US customary units (inches, feet, yards, miles). Converting lets you read a product spec, follow building plans, or compare a running route no matter which system the original used.
Length Units Explained
The metric units here scale by powers of ten: 10 mm = 1 cm, 100 cm = 1 m, and 1,000 m = 1 km. This makes metric conversions easy because you simply shift the decimal point. The imperial and US customary units relate to each other in fixed but uneven steps: 12 inches = 1 foot, 3 feet = 1 yard, and 1,760 yards (5,280 feet) = 1 mile. Inches, feet, and yards are best for room dimensions, clothing, and short distances, while miles and kilometers suit travel and road distances. Crossing between the two systems always traces back to the inch, which is defined as exactly 25.4 millimeters.
How to Convert Length Units
The reliable method is to convert through a base unit, usually the meter. Multiply your value by the unit's size in meters, then divide by the size of the target unit. The exact anchors are: 1 in = 0.0254 m, 1 ft = 0.3048 m, 1 yd = 0.9144 m, and 1 mi = 1,609.344 m. For metric, 1 cm = 0.01 m, 1 mm = 0.001 m, and 1 km = 1,000 m. Example: convert 5 feet to centimeters. First 5 ft x 0.3048 = 1.524 m, then 1.524 m / 0.01 = 152.4 cm. Another: 10 km to miles is 10,000 m / 1,609.344 = about 6.2137 miles. Reverse any conversion by dividing instead of multiplying.
Common Uses
- Reading furniture and appliance dimensions before buying
- Converting clothing and shoe measurements between regions
- Following construction or DIY plans drawn in metric or imperial
- Comparing running, cycling, or driving distances (miles vs kilometers)
- Sizing TVs, monitors, and screens given in inches
- International shipping that requires package dimensions in cm or in
- Reading maps and route distances when traveling abroad
Accuracy Tips
Keep the defining factors exact: 1 inch is exactly 25.4 mm, 1 foot exactly 0.3048 m, and 1 mile exactly 1,609.344 m. Round only at the final step to avoid drift. A quick mental check: 1 inch is about 2.54 cm, and 1 meter is roughly 3.28 feet. Watch the unit symbols carefully, since mm, cm, m, and km differ by factors of ten and a misplaced decimal is the most common mistake.
Frequently Asked Questions
How many centimeters are in an inch?
There are exactly 2.54 centimeters in one inch, because the inch is defined as exactly 25.4 millimeters. So 10 inches equals 25.4 cm, and 12 inches (one foot) equals 30.48 cm.
How do I convert kilometers to miles?
Divide the number of kilometers by 1.609344, or multiply by about 0.621371. For example, 5 km is about 3.107 miles, and 100 km is about 62.14 miles.
How many feet are in a meter?
One meter equals about 3.28084 feet, which is 3 feet and roughly 3.37 inches. Going the other way, one foot is exactly 0.3048 meters.
What is the difference between a yard and a meter?
A meter is slightly longer than a yard. One yard equals exactly 0.9144 meters, so a meter is about 1.0936 yards, or roughly 8.6 centimeters longer than a yard.
How many millimeters are in a centimeter?
There are exactly 10 millimeters in one centimeter. Since metric units scale by ten, 1 cm = 10 mm, 1 m = 1,000 mm, and 1 m = 100 cm.