Speed Converter
Convert speed and velocity units instantly — km/h, mph, m/s, knots, and more. Free online speed converter for travel, sports, physics, and engineering.
Understanding Speed and Velocity
Speed measures how fast an object moves. Velocity includes both speed and direction. You encounter speed measurements daily — driving, running, flying, or watching weather reports. Speed equals distance traveled divided by time taken.
Different fields use different speed units. Roads use kilometers per hour (most countries) or miles per hour (US, UK). Science uses meters per second. Aviation and maritime navigation use knots (nautical miles per hour). Each unit serves specific practical purposes.
Speed Conversion Formulas
km/h to mph
mph = km/h × 0.621371
Example: 100 km/h × 0.621371 = 62.14 mph
mph to km/h
km/h = mph × 1.60934
Example: 60 mph × 1.60934 = 96.56 km/h
km/h to m/s
m/s = km/h ÷ 3.6
Example: 72 km/h ÷ 3.6 = 20 m/s
m/s to km/h
km/h = m/s × 3.6
Example: 10 m/s × 3.6 = 36 km/h
km/h to knots
knots = km/h × 0.539957
Example: 100 km/h × 0.539957 = 54.00 kn
knots to km/h
km/h = knots × 1.852
Example: 50 kn × 1.852 = 92.6 km/h
Common Speed Conversions
| Speed | mph | m/s | Knots |
|---|---|---|---|
| 10 km/h | 6.21 mph | 2.78 m/s | 5.40 kn |
| 50 km/h | 31.07 mph | 13.89 m/s | 27.00 kn |
| 100 km/h | 62.14 mph | 27.78 m/s | 54.00 kn |
| 60 mph | 96.56 km/h | 26.82 m/s | 52.14 kn |
| 100 mph | 160.93 km/h | 44.70 m/s | 86.90 kn |
| 1 m/s | 2.24 mph | 1.94 kn |
Speed Reference Table
| Object/Activity | km/h | mph | m/s |
|---|---|---|---|
| Walking speed (average) | 5 km/h | 3.1 mph | 1.4 m/s |
| Running (jogging) | 8-10 km/h | 5-6.2 mph | 2.2-2.8 m/s |
| Running (sprinting) | 25-30 km/h | 15.5-18.6 mph | 6.9-8.3 m/s |
| City driving | 30-50 km/h | 19-31 mph | 8.3-13.9 m/s |
| Highway driving | 90-120 km/h | 56-75 mph | 25-33.3 m/s |
| Commercial aircraft | 800-900 km/h | 500-560 mph | 222-250 m/s |
| Sound (at sea level) | 1,235 km/h | 767 mph | 343 m/s |
| Light (in vacuum) | 1.08 billion km/h | 670.6 million mph | 299,792,458 m/s |
Vehicle Speed Comparison
| Vehicle | Typical Speed | Maximum Speed |
|---|---|---|
| Electric scooter | 25 km/h | 45 km/h |
| Bicycle (casual) | 15-20 km/h | 30 km/h |
| Bicycle (racing) | 40 km/h | 70 km/h |
| Motorcycle | 80-120 km/h | 200+ km/h |
| Car (city) | 40-60 km/h | 100 km/h |
| Car (highway) | 100-130 km/h | 200+ km/h |
| High-speed train | 250-320 km/h | 430 km/h |
| Formula 1 car | 200-300 km/h | 370 km/h |
Speed Unit Reference Table
| Unit | Symbol | Equals 1 Unit In m/s | Common Uses |
|---|---|---|---|
| Meter/second | m/s | 1 m/s | Science, physics, engineering |
| Kilometer/hour | km/h | 0.2778 m/s | Road signs, vehicles (most countries) |
| Mile/hour | mph | 0.4470 m/s | Road signs, vehicles (US, UK) |
| Knot | kn | 0.5144 m/s | Aviation, maritime navigation |
| Foot/second | ft/s | 0.3048 m/s | Engineering (US), ballistics |
When to Use Each Speed Unit
Road Traffic
Speed limits, vehicle speedometers, traffic reports (most countries)
Sports
Cycling, running, skiing speeds
Weather
Wind speeds (many countries)
Road Traffic
Speed limits, vehicle speedometers (US, UK)
Sports
Baseball pitches, football throws, track events (US)
Weather
Wind speeds, storm warnings (US, UK)
Science
Physics calculations, research, experiments
Engineering
Fluid dynamics, structural analysis
Weather
Scientific meteorology, wind measurements
Aviation
Aircraft speed, wind speed, air traffic control
Maritime
Ship speed, current speed, navigation
Meteorology
Aviation weather, marine forecasts
Speed Calculation Tips
Calculate Average Speed
Divide total distance by total time. Example: 150 km in 2 hours = 150 ÷ 2 = 75 km/h average speed. This works regardless of speed variations during the journey.
Convert Travel Time
Time = Distance ÷ Speed. Example: 300 km at 100 km/h = 300 ÷ 100 = 3 hours. Add extra time for stops, traffic, and delays.
Quick km/h to mph Estimate
Divide km/h by 8, then multiply by 5. Example: 100 km/h ÷ 8 = 12.5 × 5 = 62.5 mph (actual: 62.14 mph). Good enough for quick mental estimates.
Frequently Asked Questions
What is the speed of sound?
Sound travels at 343 m/s (1,235 km/h, 767 mph) in dry air at 20°C. Speed varies with temperature, humidity, and altitude. Supersonic speeds exceed Mach 1 (the speed of sound).
What is a knot and why do ships use it?
One knot equals one nautical mile per hour (1.852 km/h, 1.151 mph). Nautical miles match Earth's latitude measurements, making navigation calculations simpler. One nautical mile equals one minute of latitude.
How fast is the speed of light?
Light travels at exactly 299,792,458 m/s in vacuum (about 300,000 km/s or 186,000 miles/s). Nothing travels faster. This universal constant defines the maximum speed for all matter and information.
What is Mach number?
Mach number expresses speed relative to the speed of sound. Mach 1 equals the speed of sound. Mach 2 means twice the speed of sound. Fighter jets and spacecraft use Mach numbers for high-speed flight.
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