Screens are sold in inches, passports record your height in centimeters, product specifications arrive in millimeters, and road signs switch between miles and kilometers depending on the country. This length converter translates between all of them at once. Enter any value, choose its unit, and you will see the same length in millimeters, centimeters, meters, kilometers, inches, feet, yards and miles, plus a feet-and-inches readout that is especially handy for heights. Below the tool you will find how the conversion factors work, worked examples, a height chart and the mistakes that most often lead people astray. If you are counting a walk rather than measuring a length, our Steps to Miles Calculator covers that side of things.
| Unit | Value | Symbol |
|---|
As feet and inches: 2 ft 9.46 in (total 33.4646 in).
Two systems of measurement, one exact bridge
The metric system is built on powers of ten, which makes it beautifully regular: ten millimeters make a centimeter, a hundred centimeters make a meter, and a thousand meters make a kilometer. The imperial and US customary system grew up over centuries instead, so its steps are uneven: twelve inches make a foot, three feet make a yard, and 1,760 yards make a mile. Neither system is going anywhere. Metric is the language of science and of most of the world, while inches, feet and miles remain the everyday units in the United States and survive in pockets elsewhere, from British road signs to the screen size of every phone and television on earth.
What makes conversion between them reliable is that the two systems are joined by an exact definition: since 1959, one inch has been defined as exactly 2.54 centimeters. Every factor in this converter flows from that single bridge and from the fixed steps within each system, so none of the results here are approximations of approximations. A foot is exactly 30.48 cm, a yard exactly 0.9144 m, and a mile exactly 1.609344 km.
Length conversion formulas and factors
The cleanest way to convert any length by hand is to pass through meters: convert your value into meters first, then convert out into the unit you want. The factors you need are:
- 1 inch = 25.4 mm = 2.54 cm = 0.0254 m
- 1 foot = 12 inches = 30.48 cm = 0.3048 m
- 1 yard = 3 feet = 36 inches = 0.9144 m
- 1 mile = 5,280 feet = 1,609.344 m = 1.609344 km
- 1 meter = 100 cm = 1,000 mm = 3.28084 feet = 39.3701 inches
- 1 centimeter = 10 mm = 0.393701 inches
- 1 kilometer = 1,000 m = 0.621371 miles
Going from a smaller unit to a larger one makes the number smaller, and going the other way makes it bigger. That simple sanity check catches most slips: if you convert millimeters into inches and the number grows, something has gone wrong, because inches are the larger unit.
Worked example: 85 cm in inches
“Convert 85 cm into inches” is a typical everyday search; 85 cm turns up as a clothing size, a suitcase dimension and a common furniture measurement. Using the bridge factor, divide by 2.54:
- Start with the centimeter value: 85.
- Divide by 2.54: 85 / 2.54 = 33.4646.
- So 85 cm = 33.4646 inches, usually written as 33.46 in.
Expressed the way heights are usually spoken, 33.4646 inches is 2 whole feet (24 inches) with 9.46 inches left over: 2 ft 9.46 in. The same 85 cm is also 850 millimeters, 0.85 meters and 0.9296 yards, all of which the converter shows at once. A second quick example shows the pattern at a larger scale: half an inch, a measurement that appears constantly in hardware and sewing, is 0.5 x 25.4 = exactly 12.7 mm, not 12.5 mm as many people guess.
Converting heights: centimeters to feet and inches
Height is the conversion people need most, because official documents, sports profiles and medical records in metric countries use centimeters, while everyday conversation in the United States uses feet and inches. The method has three steps: divide the centimeters by 2.54 to get total inches; divide that by 12 and keep the whole number as feet; whatever inches remain are the second figure. For example, 170 cm / 2.54 = 66.93 inches in total, and 66.93 inches splits into 5 feet (60 inches) plus 6.93 inches, giving the familiar 5 ft 6.93 in. The converter’s readout under the results table performs this split for any value you enter.
| Height (cm) | Total inches | Feet and inches |
|---|---|---|
| 150 | 59.06 | 4 ft 11.06 in |
| 155 | 61.02 | 5 ft 1.02 in |
| 160 | 62.99 | 5 ft 2.99 in |
| 165 | 64.96 | 5 ft 4.96 in |
| 170 | 66.93 | 5 ft 6.93 in |
| 175 | 68.90 | 5 ft 8.90 in |
| 180 | 70.87 | 5 ft 10.87 in |
| 185 | 72.83 | 6 ft 0.83 in |
| 190 | 74.80 | 6 ft 2.80 in |
| 195 | 76.77 | 6 ft 4.77 in |
Shoe sizing runs on the same two units: size charts list foot length in centimeters and inches side by side. If you are measuring a foot rather than a person, our Shoe Size Calculator turns that length into US, UK and EU sizes.
Length conversion reference table
Keep these equivalents nearby and most everyday conversions become one-step multiplications:
| Unit | In meters | Handy equivalent |
|---|---|---|
| 1 millimeter (mm) | 0.001 m | 0.0394 inches |
| 1 centimeter (cm) | 0.01 m | 0.3937 inches |
| 1 meter (m) | 1 m | 3.2808 feet |
| 1 kilometer (km) | 1,000 m | 0.6214 miles |
| 1 inch (in) | 0.0254 m | 2.54 centimeters |
| 1 foot (ft) | 0.3048 m | 30.48 centimeters |
| 1 yard (yd) | 0.9144 m | 91.44 centimeters |
| 1 mile (mi) | 1,609.344 m | 1.6093 kilometers |
Everyday length conversions in practice
A few situations account for most of the conversions people run. Screen sizes are quoted as a diagonal in inches everywhere in the world, so a 55-inch television measures 55 x 2.54 = 139.7 cm corner to corner, the number you need when checking whether it fits a stand bought from a metric retailer. Runners meet the mile and kilometer mix constantly: a 5 km fun run is 3.11 miles, and a full marathon of 42.195 km is 26.22 miles, which is why pace figures rarely match between apps set to different units. At home, a room described as 12 ft by 10 ft in an older property listing is 3.66 m by 3.05 m, the figures a flooring or furniture supplier working in metric will ask for. And anyone buying fabric crosses the yard line regularly: cloth sold by the meter in most shops is still cut by the yard in many pattern books, with 3 yards equal to 2.74 m. In every case the same habit protects you: convert with the exact factor, and only round the answer you are going to use.
Common length conversion mistakes
Reading decimal feet as feet and inches. A result of 5.9 ft does not mean 5 feet 9 inches. The .9 is nine tenths of a foot, which is 10.8 inches, so 5.9 ft is really 5 ft 10.8 in. Always split the decimal part by multiplying it by 12, as the readout under the converter does.
Assuming half an inch is 12.5 mm. Because 25 mm feels like it should pair with an inch, many people halve it to 12.5. The exact figure is 12.7 mm, and that 0.2 mm gap is enough to make a bolt, a drill bit or a phone case the wrong size.
Rounding the bridge factor. Using 2.5 instead of 2.54 for centimeter-to-inch work is fine for a rough guess across a room, but across a mile the shortcut throws the answer out by more than 25 meters. Keep 2.54 intact and round only the final answer.
Confusing millimeters and centimeters. A misplaced factor of ten is the classic specification error: a part drawn as 85 mm ordered as 85 cm arrives ten times too large. When a number looks surprising, check which of the two units the document actually used.
Mixing up yards and meters. A yard (0.9144 m) is close to a meter but not equal to one; over a 100-unit run the difference is more than 8 meters, which is why athletics quietly replaced the 100-yard dash with 100 meters.
Frequently asked questions
How many millimeters are in an inch?
Exactly 25.4 millimeters. The inch is defined as exactly 2.54 centimeters, so every inch conversion is exact: 1 in = 25.4 mm = 2.54 cm.
What is 85 cm in inches?
85 cm is 33.46 inches. Divide 85 by 2.54 to get 33.4646 inches, which is also 2 feet 9.46 inches.
How many centimeters are in a foot?
30.48 centimeters exactly. One foot is 12 inches, and 12 x 2.54 cm = 30.48 cm.
How do I convert centimeters to feet and inches?
First divide the centimeters by 2.54 to get total inches. Then divide by 12: the whole number is feet and the remainder is inches. Example: 170 cm = 66.93 in = 5 ft 6.93 in.
How many feet are in a meter?
1 meter is 3.28084 feet, roughly 3 feet 3.37 inches. For a quick estimate, multiply meters by 3.28.
How long is a mile in kilometers?
One mile is exactly 1.609344 kilometers, usually rounded to 1.61 km. Conversely, 1 km is about 0.621 miles.