🏎️ Speed Conversion Calculator 2026
Convert between mph, km/h, m/s, knots, Mach, and speed of light
100 km/h = 62.14 mph
Formula: value × 0.6214
📊 All Conversions
Common Speed Conversions
| From | To | Multiply by |
|---|---|---|
| 1 km/h | mph | 0.6214 |
| 1 mph | km/h | 1.6093 |
| 1 m/s | km/h | 3.6 |
| 1 knot | km/h | 1.852 |
| 1 knot | mph | 1.151 |
| Mach 1 (sea level) | km/h | 1,234.8 |
Notable Speeds
| Object/Reference | Speed |
|---|---|
| 🚶 Walking | 5 km/h (3.1 mph) |
| 🚴 Cycling | 20-30 km/h (12-19 mph) |
| 🚗 Highway driving | 100-130 km/h (62-80 mph) |
| 🚄 High-speed train (TGV) | 320 km/h (200 mph) |
| ✈️ Commercial jet | 900 km/h (560 mph, Mach 0.85) |
| 🔊 Speed of sound (sea level) | 1,234.8 km/h (767 mph, Mach 1) |
| 🚀 Space Station orbit | 27,600 km/h (17,150 mph) |
| 💡 Speed of light | 299,792 km/s (186,282 mi/s) |
Understanding Speed Units
🚗 km/h & mph
Most common units. km/h used globally; mph in US, UK. 100 km/h ≈ 62 mph. Car speedometers show both in many countries.
⚓ Knots
Nautical speed. 1 knot = 1 nautical mile/hour = 1.852 km/h. Used in aviation and maritime. Named for rope knots used historically.
✈️ Mach Number
Ratio to speed of sound. Mach 1 = 1,234.8 km/h at sea level. Varies with altitude and temperature. Supersonic = Mach 1+.
💡 Speed of Light
c = 299,792,458 m/s. Universal speed limit. Nothing with mass can reach it. Light travels 1 ft in ~1 nanosecond.
Frequently Asked Questions
How do I convert km/h to mph?
Multiply by 0.6214. Example: 100 km/h × 0.6214 = 62.14 mph. Quick
estimate: divide km/h by 1.6.
How do I convert mph to km/h?
Multiply by 1.6093. Example: 60 mph × 1.6093 = 96.56 km/h. Quick
estimate: multiply mph by 1.6.
What is a knot?
1 nautical mile per hour = 1.852 km/h = 1.151 mph. Used in
aviation and maritime. Named for knots on a ship's log line used to measure speed.
How do I convert knots to mph?
Multiply by 1.151. Example: 100 knots = 115.1 mph = 185.2 km/h.
Knots are slightly faster than mph.
What is Mach number?
Speed relative to sound. Mach 1 = speed of sound. At sea level
(15°C): ~1,234.8 km/h (767 mph). Mach 2 = twice sound speed.
What is the speed of sound?
~343 m/s (1,234.8 km/h, 767 mph) at sea level, 15°C. Varies with
temperature and medium. Faster in water (~1,480 m/s) and steel (~5,960 m/s).
What is the speed of light?
299,792,458 m/s exactly (in vacuum). ≈ 1.08 billion km/h. Nothing
can exceed this. Light reaches Moon in ~1.3 seconds.
How do I convert m/s to km/h?
Multiply by 3.6. Example: 10 m/s × 3.6 = 36 km/h. This is because
1 km = 1000 m and 1 hour = 3600 seconds.
Why do ships and planes use knots?
Based on nautical miles. 1 nautical mile = 1 minute of latitude.
Makes navigation calculations easier. International standard for maritime and aviation.
What is supersonic speed?
Faster than Mach 1. Creates sonic boom. Concorde flew at Mach
2.04. Modern jets rarely fly supersonic over land due to noise regulations.
What is hypersonic speed?
Above Mach 5 (6,174+ km/h). Extreme heating from air friction.
Space reentry vehicles, some missiles, experimental aircraft.
How fast does the Earth rotate?
~1,670 km/h (1,040 mph) at equator. Slower at higher latitudes.
You don't feel it because everything moves together at constant speed.
How fast does Earth orbit the Sun?
~107,000 km/h (66,600 mph). Completes orbit in 365.25 days. We
don't feel it — no acceleration since it's nearly circular.
What is a furlong per fortnight?
Humorous unit = 201.168 m / 1,209,600 s ≈ 0.000166 m/s ≈ 0.6 km/h.
Sometimes used as joke in physics to illustrate unit conversion.
How do I convert feet per second to mph?
Multiply by 0.6818. Example: 100 ft/s × 0.6818 = 68.18 mph. Or
divide ft/s by 1.467.
What speed units do scientists use?
m/s (meters per second) is SI standard. Also: km/s for astronomy,
c (light speed) for relativity. mph/km/h for everyday applications.
How accurate is this speed converter?
Uses exact conversion factors. Speed of sound/light values are
standard reference conditions. Results are mathematically precise.