Speed Converter
Convert speed between mph, km/h, m/s, knots, and ft/s instantly.
Common Speed Reference
| Description | mph | km/h | m/s |
|---|---|---|---|
| Walking (casual) | 3.1 | 5 | 1.4 |
| Cycling (leisure) | 12 | 19 | 5.3 |
| City speed limit (US) | 25 | 40 | 11.1 |
| Highway speed (US) | 65 | 105 | 29 |
| Bullet train (Shinkansen) | 200 | 320 | 89 |
| Speed of sound (sea level) | 767 | 1,235 | 343 |
Frequently Asked Questions
How do I convert mph to km/h?
Multiply mph by 1.60934. For example, 60 mph = 60 × 1.60934 = 96.56 km/h. A quick approximation is to multiply by 1.6. To go the other way, multiply km/h by 0.62137.
What is a knot?
A knot is one nautical mile per hour — approximately 1.852 km/h or 1.151 mph. Knots are used in maritime and aviation navigation. The term originated from the practice of measuring ship speed by counting knots in a rope tossed overboard.
How fast is the speed of sound?
The speed of sound in dry air at 20°C is approximately 343 m/s, 1,235 km/h, or 767 mph. It varies with temperature and medium — sound travels faster in warmer air and much faster through water (about 1,480 m/s) and steel (about 5,130 m/s).
What is Mach 1?
Mach 1 is the speed of sound in the current medium. At sea level in standard atmosphere (15°C), Mach 1 ≈ 340 m/s ≈ 1,225 km/h ≈ 761 mph. At cruising altitude (−57°C), Mach 1 drops to about 295 m/s / 1,062 km/h / 660 mph.
What is the speed of light?
The speed of light in a vacuum is 299,792,458 m/s — exactly, by definition of the metre. This is approximately 300,000 km/s, 186,000 miles per second, or 1.08 billion km/h.