Your result will appear here
Fill in the fields and press Calculate.
Speed is measured differently depending on context and country: km/h on most road signs, mph in the US and UK, m/s in physics, and knots at sea and in the air. Converting between them is a constant need for driving abroad, science homework, sailing or aviation.
Enter a value, pick the units, and the converted speed appears at once.
Speed Converter: step-by-step worked example
What is a 65 mph speed limit in km/h?
- Value
- 65
- From
- Miles/hour (mph)
- To
- Kilometers/hour (km/h)
- 1
Source unit in the base unit
k₁ = one source unit expressed in metres per second
1 mph = 0.44704 m/s = 0.447 m/s
- 2
Target unit in the base unit
k₂ = one target unit expressed in metres per second
1 km/h = 0.2777777778 m/s = 0.2778 m/s
- 3
Convert to the base unit
m/s = Value × k₁
65 × 0.44704 = 29.0576 m/s
- 4
Convert to the target unit
Result = m/s ÷ k₂
29.0576 ÷ 0.2777777778 = 104.60736 km/h
- 5
Direct conversion factor
Factor = k₁ ÷ k₂
0.44704 ÷ 0.2777777778 = 1.6093
- m/s29.0576
- km/h104.6074
- mph65
- kn56.4835
- ft/s95.3333
Good to know: 1 km/h = 1,000 m ÷ 3,600 s = 1/3.6 m/s. The knot (nautical mile per hour) is rounded to 0.514444 m/s here (exactly 1,852/3,600).
Speed Converter — how it works
Key conversion factors
| Conversion | Factor |
|---|---|
| 1 m/s | 3.6 km/h |
| 1 mph | 1.609344 km/h |
| 1 knot | 1.852 km/h |
| 1 km/h | 0.621371 mph |
| 1 ft/s | 0.3048 m/s |
All speeds share one base — metres per second — so the tool converts to m/s and back to your target unit.
Where each unit is used
- km/h: road speed in most of the world.
- mph: road speed in the US and UK.
- m/s: the SI unit, used in physics and engineering.
- knots: one nautical mile per hour, used in maritime and aviation navigation.
- ft/s: occasional US engineering and ballistics contexts.
Quick estimates
- mph → km/h: multiply by 1.6 (60 mph ≈ 96 km/h).
- km/h → mph: multiply by 0.62 (100 km/h ≈ 62 mph).
- A knot is very close to 1.15 mph.
Where it helps
- Reading a foreign speed limit in your own units
- Physics problems that mix m/s and km/h
- Understanding wind or vessel speed in knots
Worked example
You're driving abroad and the limit reads 100 km/h, but your speedometer is in mph. Converting: 100 × 0.621371 = 62.14 mph. Going the other way, a 60 mph US limit is 60 × 1.609344 = 96.56 km/h. For a maritime example, a vessel doing 20 knots is travelling 20 × 1.852 = 37.04 km/h — a knot being one nautical mile per hour. The quick shortcut "km/h × 0.62 ≈ mph" gets you 62 for a fast sanity check, with the converter giving the exact 62.14.
Speed conversion table (km/h, mph, m/s, knots)
| km/h | mph | m/s | Knots |
|---|---|---|---|
| 10 | 6.2 | 2.8 | 5.4 |
| 30 | 18.6 | 8.3 | 16.2 |
| 50 | 31.1 | 13.9 | 27 |
| 60 | 37.3 | 16.7 | 32.4 |
| 70 | 43.5 | 19.4 | 37.8 |
| 80 | 49.7 | 22.2 | 43.2 |
| 90 | 55.9 | 25 | 48.6 |
| 100 | 62.1 | 27.8 | 54 |
| 110 | 68.4 | 30.6 | 59.4 |
| 120 | 74.6 | 33.3 | 64.8 |
| 130 | 80.8 | 36.1 | 70.2 |
| 140 | 87 | 38.9 | 75.6 |
| 150 | 93.2 | 41.7 | 81 |
Frequently asked questions
How do I convert km/h to mph?+
Multiply by 0.621371: 100 km/h × 0.621371 = 62.14 mph. For a quick estimate, multiply by 0.62. The tool handles every unit combination.
How do I convert mph to km/h?+
Multiply by 1.609344: 60 mph = 96.56 km/h. A rough estimate is mph × 1.6. Just pick the units and enter the value.
What is a knot?+
A knot is one nautical mile per hour, equal to 1.852 km/h (about 1.15 mph). It's used in maritime and aviation navigation because it ties neatly to latitude.
How do I convert m/s to km/h?+
Multiply by 3.6: 10 m/s = 36 km/h. Metres per second is the SI unit, so the converter uses it as the base for all speed conversions.
What is 100 km/h in mph?+
62.14 mph. That's a common motorway/highway speed, which is why the ~62 mph figure is worth remembering when driving between metric and imperial countries.
Why do ships and planes use knots?+
One knot is one nautical mile per hour, and a nautical mile is defined by the Earth's geometry (one minute of latitude), which makes navigation calculations simpler.
About this page
- Publisher:
- Kalkoro — Teknolojig Bilişim Teknolojileri A.Ş., İstanbul
- Written by:
- Ahmet Tur — Editor (Math, date & time, unit conversion, physics & chemistry, everyday tools)
- Reviewed by:
- Kübra Yıldız — Editor
Parameters come from official sources; the last update date is shown at the bottom of the page.
Spotted a wrong result? Use the "Report a bug" button at the top of the page; every report is reviewed.
How we calculate and our accuracy policy →
Results are for information only. For official matters the relevant authority's calculation prevails.
Last updated: