Speed Scales: From Walking to Supersonic
🚶
Walking
3 mph / 5 km/h
🚴
Cycling
15 mph / 24 km/h
🚗
Highway
70 mph / 113 km/h
✈️
Jet Cruise
575 mph / Mach 0.85
🚀
Sound
767 mph / Mach 1
Why Knots? ⚓
Sailors and pilots use knots (nautical miles per hour) because 1 nautical mile = 1 minute of latitude. This makes navigation math much easier!
| Speed | Knots | MPH | KM/H |
|---|---|---|---|
| Light Breeze | 5 kn | 5.8 mph | 9.3 km/h |
| Cruise Ship | 20 kn | 23 mph | 37 km/h |
| Helicopter | 140 kn | 161 mph | 259 km/h |
Speed conversion formula
Speed is distance divided by time, so its factor combines a distance conversion with a time conversion. One mile per hour equals exactly 1.609344 kilometres per hour.
v_{target} = v_{source} \times f_{source\to target}
vSpeed
fCombined distance-time factor
Worked conversion example
1
Start with 60 mph
Multiply by kilometres per mile.
60 × 1.609344
2
Calculate
Hours cancel because both units use the same time base.
= 96.56064 km/h
3
Round for display
Road signage usually does not need six decimals.
≈ 96.6 km/h
Frequently Asked Questions
How do I convert mph to km/h?
To convert miles per hour to kilometers per hour, multiply by 1.609344. For example: 60 mph × 1.609 = 96.56 km/h. To convert km/h to mph, divide by 1.609 (or multiply by 0.621). Quick reference: 100 km/h = 62.14 mph.
What is a knot and why do pilots use it?
A knot equals 1 nautical mile per hour (1.151 mph or 1.852 km/h). Pilots and sailors use knots because 1 nautical mile equals 1 minute of latitude on Earth's surface, making navigation calculations simpler. A 500-knot aircraft covers about 8.33 degrees of latitude per hour.
What is Mach speed and how fast is Mach 1?
Mach is the ratio of an object's speed to the speed of sound. Mach 1 equals the speed of sound—approximately 767 mph (1,234 km/h) at sea level and 68°F. This varies with temperature and altitude. Mach 2 means twice the speed of sound (1,534 mph).
How fast is the speed of light in mph?
Light travels at approximately 670,616,629 mph (299,792 km/s or 1.08 billion km/h). At this speed, light circles Earth 7.5 times per second. This is the universal speed limit—nothing with mass can reach it.