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Length Conversion
Tool Description
Length Conversion is an online length unit conversion tool that supports mutual conversion between metric units (millimeter, centimeter, decimeter, meter, kilometer), imperial units (inch, foot, yard, mile), and traditional Chinese units (Li, Zhang, Chi, Cun). Simply enter any value and unit to instantly view the corresponding results in all other units — ideal for engineering calculations, daily life, learning, and research.
How to Use
- Enter a value
Enter a value: Enter the value to convert in the input box. Both integers and decimals are supported, e.g.
100,3.5 - Select source unit
Select source unit: Choose the unit of the current value from the dropdown (metric, imperial, or traditional Chinese units)
- View results
View results: Click the "Convert" button or simply type (auto real-time calculation) — the results area below will display the corresponding values in all units
Use Cases
- Engineering & Construction: Blueprint dimension conversion, material length calculation, quickly switch between mm/cm/m
- International Trade: Metric and imperial unit comparison, product specification translation, e.g. inches to centimeters, feet to meters
- Learning & Teaching: Unit conversion practice in math and physics courses, understanding conversion relationships between different unit systems
Core Advantages
- Free Daily Uses
The online length unit converter gives you free daily uses. Just open the page and use it — everyday conversion needs are covered at zero cost. For higher volume or more frequent use, become a member to unlock more quota
- Local & Private
All conversions run locally in your browser. Your input data is never uploaded to any server, fully protecting your privacy
- Instant Calculation
Results are calculated instantly as you type, with no waiting — all unit results are shown at a glance
- Comprehensive Units
Supports 14 length units in total, including metric (mm to km), imperial (in, ft, yd, mi) and traditional Chinese units (Li, Zhang, Chi, Cun)
- High Precision
Uses exact mathematical computation; common conversions (e.g. 1 inch = 2.54 cm) use international standard exact values and support decimal input
- Cross-platform
Works smoothly on desktop, mobile and tablet. The page is responsive and lets you convert units anytime, anywhere
Metric Unit Conversion Relationships
The metric system (SI) uses meter (m) as the base unit, with adjacent units following a factor-of-10 relationship:
| Unit Name | Abbr | Conversion | Equivalent Meters |
|---|---|---|---|
| Millimeter | mm | 1 mm = 0.001 m | 0.001 |
| Centimeter | cm | 1 cm = 0.01 m | 0.01 |
| Decimeter | dm | 1 dm = 0.1 m | 0.1 |
| Meter | m | 基准单位 | 1 |
| Kilometer | km | 1 km = 1,000 m | 1,000 |
Imperial vs Metric Comparison
Imperial units are widely used in the US and UK. Below are the conversion relationships between imperial and metric units:
| Imperial Unit | Abbr | To Metric | Common Use |
|---|---|---|---|
| Inch | in | 1 in = 2.54 cm = 0.0254 m | Screen sizes, pipe specifications |
| Foot | ft | 1 ft = 12 in = 0.3048 m | Body height, floor height |
| Yard | yd | 1 yd = 3 ft = 0.9144 m | Track & field, fabric length |
| Mile | mi | 1 mi = 1,760 yd = 1,609.344 m | Road distance, speed limits |
Traditional Chinese Length Units
Traditional Chinese length units have a long history. Below are the conversion relationships with the modern metric system:
| Unit | To Metric | Note |
|---|---|---|
| Li | 1 里 = 500 m | Commonly used for distance between two places |
| Zhang | 1 丈 = 10/3 m ≈ 3.3333 m | 1 Zhang = 10 Chi |
| Chi | 1 尺 = 1/3 m ≈ 0.3333 m | 1 Chi = 10 Cun |
| Cun | 1 寸 = 1/30 m ≈ 0.03333 m | Commonly used in TCM acupuncture |
FAQ
1 inch = 2.54 centimeters (cm). This is the international standard definition, with the precise conversion being 1 in = 0.0254 m. For example, a 15.6-inch laptop screen has a diagonal length of approximately 39.62 cm.
1 mile = 1.609344 kilometers (km). In other words, 1 mile ≈ 1.6 km. If you see a speed limit of 60 mph (miles per hour), that is approximately 96.6 km/h.
1 Li = 500 meters, or half a kilometer. So the Chinese saying "a journey of a thousand Li" equals about 500 km, and the Great Wall (called "Ten Thousand Li Wall" in Chinese) totals about 21,000 Li, or roughly 10,500 km.
No. All conversion calculations run entirely in your browser using pure JavaScript math. Your input data never leaves your device.
This tool uses JavaScript double-precision floating-point numbers (64-bit IEEE 754) for calculations, which is sufficiently accurate for the vast majority of everyday scenarios. Decimal portions are capped at 6 significant decimal places, and excessively long decimals are automatically truncated. For extremely large or small values, there may be minor errors due to floating-point precision limitations, but this has virtually no practical impact.
This tool uses the traditional Chinese market system standard: 1 Chi = 1/3 meter ≈ 0.3333 m = 33.33 cm, 1 Cun = 1/30 meter ≈ 0.03333 m = 3.333 cm. Note that the traditional Chinese "Cun" and the modern "inch" are different concepts: 1 inch = 2.54 cm, while 1 market Cun ≈ 3.333 cm.
14 units in total. Including metric (mm, cm, dm, m, km), imperial (in, ft, yd, mi) and traditional Chinese units (Li, Zhang, Chi, Cun). Enter any one unit and convert to all the others at once.
Yes. The tool supports any unit as the input source. Simply select the corresponding "source unit" and convert to all other units — no need to start from meters.
Yes. After entering a value and selecting the source unit, the results area lists the converted values for all 14 units simultaneously, making comparison and verification easy.
More worry-free. Unlike doing the math by hand or looking up tables, this tool has all conversion factors built in and automatically outputs results for every unit, avoiding mistakes from wrong formulas or coefficients.
Mobile works, and there is no hard input limit. The page is responsive and works on phones, tablets and desktops; the input box accepts numbers of any size, with only browser floating-point precision affecting extremely large values.
Free daily uses included. Everyday light conversion needs are covered at zero cost — just open the page, no login required. For higher volume or more frequent use, become a member to unlock more quota.
Content last updated：2026-07-16
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