Length Converter
Convert between metric and imperial length in one place. Enter a value, pick the unit you are starting from, and the full table updates as you type — no need to run the same search twice for "cm to inches" and "inches to cm".
| Unit | Value |
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How it works
Every conversion on this page runs through one base unit: the meter. Each unit has a fixed conversion factor — an inch is exactly 0.0254 m, a foot is exactly 0.3048 m, a yard is 0.9144 m, and a mile is exactly 1,609.344 m. To convert any unit to any other, we multiply your input by the source unit's factor to get meters, then divide by the target unit's factor. This two-step approach means there is no need for a separate formula for each pair of units — the metric base makes every conversion a single calculation.
The imperial factors are exact because they are defined in terms of metric units, not measured. The inch was redefined in 1959 as exactly 25.4 mm, which permanently anchored imperial units to the metric system and eliminated the drift that had accumulated in older conversion tables. That is why centimeters to inches converts as a clean division: inches = cm ÷ 2.54. Going the other way, multiply by 2.54.
Precision is capped at eight significant digits, which exceeds the accuracy of any tape measure, ruler, or laser distance meter available to consumers. If you are working with manufacturing tolerances or engineering specifications, note that the tool cannot compensate for the precision of your original measurement — a dimension quoted to the nearest millimeter will not gain accuracy by being converted to microinches.
One important exception is the nautical mile, which equals exactly 1,852 meters. It is defined as one minute of arc of latitude, which makes it naturally suited for navigation by sea and air. The statute mile used on roads is 1,609.344 m — about 15% shorter. Using the wrong mile in aviation or maritime navigation is not just an accounting error; it compounds dangerously over distance.
Real-world applications
Length conversion is a daily necessity in international trade, construction, tailoring, and travel. E-commerce sellers on Amazon, eBay, or Etsy routinely need to convert product dimensions listed in centimeters to inches for US buyers, or vice versa when sourcing from Asian manufacturers. A package listed as 30 × 20 × 10 cm needs to be converted to inches for US customers who think in feet and inches — and then both may need to be checked against carrier size limits expressed in linear inches.
In construction and interior design, metric and imperial measurements appear on the same project when materials are sourced internationally. European-designed furniture may list dimensions in centimeters while US building codes reference feet and inches. Health and fitness tracking is another crossover area: height is recorded in centimeters in most of the world but in feet and inches in the US, which is why our height converter splits the remainder into feet and inches automatically.
For education, understanding the relationship between metric and imperial units builds number sense and prepares students for international collaboration in science and engineering, where metric is the universal language.
Common length conversions
| From | To |
|---|---|
| 1 cm | 0.3937 in |
| 1 inch | 2.54 cm |
| 1 foot | 30.48 cm |
| 1 meter | 3.2808 ft |
| 1 meter | 39.370 in |
| 1 yard | 0.9144 m |
| 1 kilometer | 0.6214 mi |
| 1 mile | 1.6093 km |
| 1 nautical mile | 1.852 km |
Frequently asked questions
How many inches is 1 cm?
One centimeter equals exactly 0.3937007874 inches — not a rounded approximation, but the legally defined value since 1959. An inch is defined as exactly 25.4 mm, which means the conversion factor between centimeters and inches is always exactly 2.54. To convert centimeters to inches, divide by 2.54. To convert inches to centimeters, multiply by 2.54. For quick mental math, remember that 10 cm is roughly 4 inches, which is close enough for everyday estimates.
How do I convert cm to feet and inches?
Converting centimeters to feet and inches requires a two-step process. First, divide by 2.54 to get total inches. Then divide total inches by 12 — the whole number is feet, the remainder is inches. For example, 180 cm ÷ 2.54 = 70.87 inches. Dividing 70.87 by 12 gives 5 feet with 10.87 inches remaining. So 180 cm is approximately 5 feet 10.87 inches (or about 5'11"). Our dedicated height converter handles this split automatically and also shows the decimal remainder for precision.
Which countries use the metric system and which use imperial units?
Most countries use the metric system officially, including all of Europe, Asia, Africa, and South America. The United States is the most notable holdout for everyday imperial use, though even US science and medicine rely on metric. The UK uses a mix — road signs are in miles, but measurements for food and people are often in centimeters and kilograms. Liberia and Myanmar also use mixed systems. If you are shipping internationally, knowing whether your package dimensions are in inches or centimeters can make a significant difference in cost calculations.
How do I convert between metric and imperial without a calculator?
For rough estimates, use these mental shortcuts: 1 inch is about 2.54 cm (or roughly 2.5 cm for quick math), 1 foot is about 30 cm (actually 30.48 cm), 1 meter is about 3.3 feet, 1 km is about 0.6 miles, and 1 kg is about 2.2 pounds. To convert pounds to kilograms, divide by 2.2. To convert miles to kilometers, multiply by 1.609 (or roughly 1.6). These shortcuts work well for everyday estimates but should not be used for engineering or medical calculations where precision matters.
What is the difference between a mile and a nautical mile?
A statute mile (the mile used on roads) equals exactly 1,609.344 meters. A nautical mile equals exactly 1,852 meters — about 15% longer. The nautical mile is defined as one minute of arc of latitude, which makes it naturally suited for navigation since sailors could historically estimate distance by reading latitude off a sextant. Aircraft and ships use nautical miles for this reason, which is why air navigation charts show distances in nautical miles. Confusing the two in aviation or maritime navigation could be dangerous, as the 15% error compounds over long distances.
Why does my conversion show so many decimal places?
The tool displays up to eight significant digits so that small values stay meaningful when expressed in large units. For example, 1 millimeter expressed in miles is 0.000000621371 — and without those digits, you would see zero. The extra precision is there so that converting a value and then converting it back gives you the same number you started with. Importantly, more digits displayed does not mean your original measurement was more accurate. If you measured something to the nearest centimeter, the eighth decimal place in the conversion has no physical meaning — it is just the mathematical result of the exact conversion factor.
Why do the US still use imperial units?
The US officially uses the International System of Units (SI) for many scientific and military applications, but everyday use retains imperial units. This dual-system situation stems from the cost and disruption of a full conversion — road signs, building codes, consumer products, and educational materials would all need updating. The US attempted metric adoption in the 1970s-80s but the effort lost momentum. Today, international trade and manufacturing often require metric specifications, so US exporters commonly work in both systems. If you are selling products internationally, knowing both systems is a practical necessity.
Last updated — conversions use exact unit definitions, so results stay accurate.
Estimates are for general information only — see our disclaimer.