Speed Converter — mph, km/h, m/s, knots, ft/s & Mach (Free)
Convert speed and velocity: mph, km/h, m/s, knots, ft/s, and Mach number. For driving, running, sailing, aviation. Free.
About Speed Converter
A speed converter translates velocities between miles per hour (mph), kilometers per hour (km/h), meters per second (m/s), knots (nautical miles per hour), feet per second (ft/s), and Mach (multiples of the speed of sound) — with exact conversion factors and full live updates. The ZTools Speed Converter covers driving (mph/kmh), running (min/km, min/mi pace), nautical navigation (knots), aviation (knots, Mach), athletics (m/s, ft/s), and physics (m/s as the SI base) — all on one screen with side-by-side displays.
Use cases
- Driving abroad. Speed limit signs in km/h while you're used to mph. Quick mental-check before being pulled over: 100 km/h = 62 mph, 80 km/h = 50 mph.
- Running and cycling pace. Convert "5 min/km" to mph or "8 mph" to a 7:30 mile pace. Useful when comparing training programs across countries.
- Sailing and aviation. Boat speeds are knots; converting to mph for landlubber friends. Aircraft speeds are knots and Mach; convert to km/h for airline schedules.
- Physics and engineering. Calculate kinetic energy: needs m/s. Convert from mph or km/h before plugging into KE = ½ m v².
How it works
- Enter a speed. Decimals OK. Negative values OK for "approaching" vs "receding" velocity.
- Pick the source unit. mph, km/h, m/s, ft/s, knots, Mach. The converter handles them all.
- See conversions to all common units. Single screen shows the source speed in every unit. Live updates as you type.
- Read pace conversions. Toggle the pace mode to see "minutes per mile / km" — useful for running and cycling, where pace is more intuitive than speed.
Examples
Input: 60 mph
Output: 96.56 km/h | 26.82 m/s | 88 ft/s | 52.14 knots | Mach 0.078
Input: 100 km/h
Output: 62.14 mph | 27.78 m/s | 91.13 ft/s | 53.99 knots
Input: 5:00 / km pace
Output: 12 km/h | 7.46 mph | ~3.33 m/s | 8:03 / mi pace
Frequently asked questions
What's a knot and why is it different from mph?
1 knot = 1 nautical mile per hour = 1.852 km/h ≈ 1.151 mph. Used in maritime and aviation because it relates directly to angular distance on Earth (1 nm = 1 minute of latitude).
How do I convert pace (min/km) to speed (km/h)?
speed = 60 ÷ pace. So 5:00 min/km = 60 ÷ 5 = 12 km/h. The converter has a pace mode that handles this automatically.
What is Mach number?
Speed as a fraction of the speed of sound at the same altitude/temperature. Mach 1 ≈ 343 m/s at sea level (changes with altitude). Used in aviation; "Mach 2" means twice the speed of sound.
How fast is the speed of light in everyday units?
~300,000 km/s = ~186,000 mi/s = ~671 million mph. Practical for relativity calculations; meaningless for everyday vehicles.
Are speed and velocity the same?
In physics: speed is the magnitude of velocity (no direction); velocity is a vector (with direction). The converter handles magnitudes only — direction is up to you to track.
Pro tips
- For mph ↔ km/h: × 1.6 (kmh from mph), ÷ 1.6 (mph from kmh). Quick and approximate.
- For m/s from km/h: divide by 3.6 (e.g., 100 km/h = 27.78 m/s).
- Running pace is more intuitive than speed — most runners think in min/km or min/mi.
- For aviation, knots and Mach are universal; for cars, mph or km/h depending on country.
Reviewed by Ahsan Mahmood · Last updated 2026-05-05 · Part of ZTools.
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