# Free online speed converter

> Speed is expressed in different units by context — mph for driving, km/h in metric countries, knots in aviation, m/s in physics. This converter handles them all.

Convert speed between mph, km/h, m/s, knots, ft/s, and Mach number. Useful for travel, aviation, physics, and everyday comparisons.

**Interactive version:** https://onlinecalculator.me/unit-converters/speed/
**Category:** Unit Converters

## How to use

1. Enter the speed value you want to convert.
2. Select the unit you are converting from.
3. Select the unit you want the result in.
4. The converted value appears instantly, and the table below shows equivalents in all supported units.

## Conversion reference

| From | To | Multiply by |
|---|---|---|
| mph | km/h | 1.60934 |
| km/h | mph | 0.621371 |
| m/s | km/h | 3.6 |
| km/h | m/s | 0.27778 |
| knot | mph | 1.15078 |
| mph | knot | 0.868976 |
| Mach | m/s | 340.29 |
| ft/s | mph | 0.681818 |

The Mach value uses the standard atmosphere speed of sound at sea level (340.29 m/s). Actual Mach varies with altitude and temperature.

## Everyday reference points

| Speed | mph | km/h |
|---|---|---|
| Walking pace | ~3 | ~5 |
| Bicycle | ~12 | ~20 |
| City speed limit (US) | 25–35 | 40–55 |
| Highway speed limit (US) | 65–75 | 105–120 |
| Commercial airliner | ~575 | ~925 |
| Speed of sound (sea level) | ~767 | ~1,235 |

## Notes

- The speed of sound (Mach 1) is modeled at sea level in dry air at 20°C (343 m/s). It decreases with altitude.
- Knots are the standard unit in aviation and maritime navigation worldwide.
- Results are rounded to 6 decimal places.

## Frequently asked questions

### How do you convert mph to km/h?

Multiply by 1.60934. Example: 60 mph × 1.60934 = 96.56 km/h. To reverse, divide by 1.60934 (or multiply by 0.621371).

### How many meters per second is 100 km/h?

100 km/h = 27.778 m/s. Divide km/h by 3.6 to get m/s. Example: 100 ÷ 3.6 = 27.778 m/s.

### What is a knot in mph?

1 knot = 1.15078 mph, or 1.852 km/h. Knots are nautical miles per hour, where 1 nautical mile = 1,852 meters.

### What is Mach 1?

Mach 1 is the speed of sound in dry air at sea level and 20°C, which is approximately 343 m/s (767 mph, 1235 km/h). The exact value varies with altitude and temperature.

### How fast is Mach 2?

Mach 2 is roughly twice the speed of sound at sea level — about 686 m/s (1534 mph, 2470 km/h). Commercial jets typically cruise near Mach 0.85.

### How do you convert feet per second to mph?

Multiply by 0.681818. Example: 88 ft/s × 0.681818 = 60 mph. Or: 60 mph = 88 ft/s exactly.

## Sources

- [Metre per second — SI unit of speed](https://en.wikipedia.org/wiki/Metre_per_second) — Wikipedia
- [Miles per hour — definition and exact conversions](https://en.wikipedia.org/wiki/Miles_per_hour) — Wikipedia
- [Knot — nautical mile per hour and conversions](https://en.wikipedia.org/wiki/Knot_(unit)) — Wikipedia

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