Speed Converter: km/h, mph, m/s, Knots
Convert km/h, mph, metres per second, knots and feet per second, with the factor shown.
Inputs
| Unit | 100 km/h is |
|---|---|
| km/h | 100 |
| mph | 62.137119 |
| m/s | 27.777778 |
| Knot | 53.99568 |
| ft/s | 91.134442 |
- Factor
- 1 km/h = 0.621371 mph
- Working
- 100 × 0.621371 = 62.137119
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What each Speed input means
- Value
- The speed to convert. Road speeds, wind speeds, running paces as speeds — any positive number.
- From
- km/h and mph for road travel, m/s for physics, knots at sea and in the air, ft/s in some engineering work.
- To
- The unit you want. All five are tied to the metre and second: a mile is 1,609.344 m and a nautical mile 1,852 m.
Speed conversion formula
result = value × (km/h in one 'from' unit ÷ km/h in one 'to' unit) · 1 mph = 1.609344 km/h
A speed is a distance per time, so its factors come straight from the length factors. A mile is 1.609344 km, so 1 mph is 1.609344 km/h. A metre per second covers 3,600 m in an hour, so it is 3.6 km/h. A knot is one nautical mile (1,852 m) an hour — 1.852 km/h, 1.151 mph — and is what ships and aircraft use. Road signs and speedometers use km/h or mph, physics uses m/s, and ft/s turns up in ballistics and some engineering. The page converts through km/h and lists your speed in every unit, so one entry answers all five.
Speed conversion worked example
100 km/h ÷ 1.609344 = 62.14 mph. The familiar shortcut that 100 km/h is 60 mph is 3.5% off; 60 mph is really 96.56 km/h.
More Speed examples
A 65 mph speed limit: 65 × 1.609344 = 104.60736 km/h — just over 100 km/h.
A 30-knot wind or boat speed: 30 × 1.852 = 55.56 km/h, about 34.5 mph.
The speed of sound in air at 20 °C, 343 m/s: 343 × 3.6 = 1,234.8 km/h, which is 767 mph.
Where the Speed converter can give the wrong answer
- Pace is not speed. Minutes per mile or per kilometre is the inverse; use the running pace calculator for that.
- Wind speeds in knots and km/h convert like any other speed; the Beaufort scale is a separate classification.
- The display rounds to six decimal places.
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Speed conversion reference table
| km/h | mph | m/s | knots |
|---|---|---|---|
| 10 | 6.2 | 2.78 | 5.4 |
| 20 | 12.4 | 5.56 | 10.8 |
| 30 | 18.6 | 8.33 | 16.2 |
| 50 | 31.1 | 13.89 | 27 |
| 60 | 37.3 | 16.67 | 32.4 |
| 80 | 49.7 | 22.22 | 43.2 |
| 100 | 62.1 | 27.78 | 54 |
| 110 | 68.4 | 30.56 | 59.4 |
| 120 | 74.6 | 33.33 | 64.8 |
| 130 | 80.8 | 36.11 | 70.2 |
| 200 | 124.3 | 55.56 | 108 |
Speed conversion FAQ
- 96.56 km/h: 60 × 1.609344.
- 62.14 mph: 100 ÷ 1.609344.
- One nautical mile an hour: 1.852 km/h, 1.151 mph or 0.514 m/s.
- Multiply by 3.6: a metre a second is 3,600 metres an hour. 10 m/s is 36 km/h; 25 m/s is 90 km/h.
- 74.6 mph: 120 ÷ 1.609344. A 130 km/h motorway limit is 80.8 mph.
- Multiply by 0.6818 (3,600 seconds an hour ÷ 5,280 feet a mile): 88 ft/s is 60 mph.
- About 1,235 km/h (767 mph) in air at 20 °C, from 343 m/s × 3.6. It is lower in colder air, which is why aircraft quote Mach numbers rather than a fixed speed.
- 112.7 km/h: 70 × 1.609344.
- Divide by 3.6: 90 km/h is 25 m/s. Multiply by 3.6 to go back.
- Divide 60 by the minutes per kilometre for km/h: 5:00 per km is 12 km/h and 6:00 per km is 10 km/h. The pace calculator does it for any distance.
- 2.237 mph. A brisk walk of about 1.5 m/s is 3.4 mph.
- 48.3 km/h: 30 × 1.609344.
- 31.1 mph — the urban speed limit in much of Europe.
- 185.2 km/h, or 115.1 mph.
- 49.7 mph: 80 ÷ 1.609344.
- Multiply by 0.44704, exactly: 60 mph is 26.82 m/s.
- 40.2 km/h: 25 × 1.609344.
- About 1.08 billion km/h: 299,792,458 m/s × 3.6.
- A nautical mile was set at one minute of latitude, so a speed in knots maps straight onto a navigation chart: 10 knots covers 10 minutes of latitude an hour. Today it is 1.852 km/h by definition.
- 1.852 km/h, exactly.