Length Converter
Convert between every common length and distance unit — metric (mm, cm, m, km) and imperial (in, ft, yd, mi) — with 6-decimal precision. Built for engineers, students, travellers and DIY projects.
Educational estimate. Calculator results are for planning and information only, not financial, tax, medical, legal, or engineering advice. Verify important decisions with official sources or a qualified professional.
Length Converter
Metres, Feet, Inches, Kilometres, Miles & More
📐 Formula & Method
Linear conversion
All units are stored as a multiplier against an internal base unit. To convert, the input is first scaled to the base, then divided by the target factor.
📋 How to Use
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1
Enter the numeric value you want to convert.
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2
Pick the source unit in the From dropdown.
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3
Pick the target unit in the To dropdown.
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4
Click Calculate. You will see the result, a full conversion table to every supported unit, and a list of common conversions.
💡 Key Insights
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1 metre = 3.2808 feet (exact factor 1/0.3048). The international foot has been defined as exactly 0.3048 m since 1959.
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1 mile = 1.6093 km. Memorise the rough rule "8 km ≈ 5 mi" for fast mental travel conversions.
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A nautical mile (used in aviation and shipping) is 1.852 km — about 15% longer than a statute mile.
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In the UK, road signs use miles; everywhere else SI metres/kilometres dominate. The US is the largest holdout for imperial in everyday use.
🧮 Worked Examples
Marathon distance
A standard marathon is 42.195 km.
Average human height
175 cm in feet/inches.
🔬 Methodology & Accuracy
Formula: Linear unit conversion with high-precision constants. All math runs client-side in your browser using IEEE-754 doubles.
Data sources: BIPM SI brochure (9th ed.); NIST SP 811 (2008 ed.); ISO 80000-1 quantities and units.
Last reviewed: January 2026 · Accuracy: Results are precise to two decimal places using IEEE-754 double-precision arithmetic. Intended for educational and planning use only.
For informational purposes only. Results are estimates based on the inputs and formulas provided. For financial, tax, medical, or legal decisions, consult a qualified professional. Rates and regulations change — always verify current figures with official sources.
Accuracy & Feedback
❓ Frequently Asked Questions
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