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Sources & Methodology
All conversion factors from NIST SI unit definitions. Base unit: meter. All values convert to meters first, then to target units.
NIST — SI Unit Conversion Reference
National Institute of Standards and Technology official conversion factors for all length units used in this calculator, including the exact inch (2.54 cm) and yard (0.9144 m) definitions.
BIPM — International Bureau of Weights & Measures
Reference for the SI base unit of length (the meter), defined since 1983 as the distance light travels in 1/299,792,458 of a second in vacuum.
Method: All inputs first convert to meters using exact factors. Output values divide meters by each target unit’s factor.
Exact factors (meters): mi=1609.344, km=1000, m=1, cm=0.01, mm=0.001, ft=0.3048, in=0.0254, yd=0.9144, nmi=1852.
Exact factors (meters): mi=1609.344, km=1000, m=1, cm=0.01, mm=0.001, ft=0.3048, in=0.0254, yd=0.9144, nmi=1852.
⏱ Last reviewed: April 2026
Length Unit Conversion Guide
Length is measured in different units depending on context: the metric system uses meters, centimeters, and kilometers; the imperial system uses inches, feet, yards, and miles. Understanding how to convert between them is essential for travel, construction, science, and international shopping.
Key Conversion Factors
1 mile = 1,609.344 m = 1.609344 km = 5,280 ft = 1,760 yd
1 km = 1,000 m = 0.621371 miles = 3,280.84 ft
1 meter = 100 cm = 3.28084 ft = 39.3701 inches = 1.09361 yards
1 foot = 12 in = 0.3048 m 1 inch = 2.54 cm 1 yard = 3 ft = 0.9144 m
All factors are exact international definitions. 1 nautical mile = 1,852 m exactly (used in aviation and maritime navigation).
Length Conversion Reference Table
| Unit | Meters | Feet | Miles | Km |
|---|---|---|---|---|
| 1 inch | 0.0254 | 0.0833 | 0.0000158 | 0.0000254 |
| 1 foot | 0.3048 | 1 | 0.000189 | 0.000305 |
| 1 yard | 0.9144 | 3 | 0.000568 | 0.000914 |
| 1 meter | 1 | 3.2808 | 0.000621 | 0.001 |
| 100 meters | 100 | 328.08 | 0.0621 | 0.1 |
| 1 km | 1,000 | 3,280.8 | 0.6214 | 1 |
| 1 mile | 1,609.3 | 5,280 | 1 | 1.6093 |
| 1 nautical mile | 1,852 | 6,076.1 | 1.1508 | 1.852 |
Common Real-World Distances
- Marathon: 42.195 km = 26.219 miles = 138,435 feet
- 5K race: 5 km = 3.107 miles = 16,404 feet
- US football field: 100 yards = 91.44 m = 300 feet (end zones add 20 yards)
- Average city block (US): approximately 80–100 m = 265–330 feet
- Equator circumference: 40,075 km = 24,901 miles
Frequently Asked Questions
1 mile = exactly 1.609344 km. This is the international statute mile definition. For quick mental math: multiply miles by 1.6 to approximate km. So 5 miles ≈ 8 km and 10 miles ≈ 16 km.
1 km = 0.621371 miles. For quick estimates, multiply km by 0.6. So 10 km ≈ 6.2 miles. A marathon (42.195 km) = 26.219 miles. A 5K = 3.107 miles.
1 meter = 3.28084 feet. Conversely, 1 foot = 0.3048 m exactly. Example: 100 m = 328.084 feet. A 6-foot person is 1.8288 m tall.
1 inch = exactly 2.54 cm. This is an exact international standard. So 12 inches (1 foot) = 30.48 cm, and 36 inches (1 yard) = 91.44 cm.
1 mile = 1,609.344 meters. Derived from: 1 mile = 5,280 feet and 1 foot = 0.3048 m. 5,280 × 0.3048 = 1,609.344 m exactly.
100 meters = 328.084 feet = 109.361 yards. The 100-meter sprint covers 328 feet 1 inch. In comparison, an American football field (100 yards) is 91.44 meters.
5 miles = 8.04672 km. Calculation: 5 × 1.609344 = 8.04672 km. A 5-mile run is slightly longer than an 8K race. For mental math: miles × 1.6 ≈ km.
Multiply inches by 2.54 (exact). To convert back: divide cm by 2.54. Example: 24 inches × 2.54 = 60.96 cm. 100 cm ÷ 2.54 = 39.37 inches.
Exactly 1,760 yards in a mile. Also: 1 mile = 5,280 feet = 1,760 yards = 63,360 inches = 1,609.344 m. The word “mile” comes from Latin mille passuum (1,000 double paces).
A nautical mile = 1,852 m = 1.15078 statute miles. It equals 1 minute of arc of latitude, making navigation charts simpler. Speed at sea is measured in knots (nautical miles per hour). 1 knot = 1.852 km/h = 1.151 mph.
Multiply meters by 3.28084. For feet and inches: multiply meters by 100, divide by 2.54 for total inches, then floor ÷ 12 for feet and remainder for inches. Example: 1.8 m × 3.28084 = 5.905 ft = 5’10.9”.
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