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Speed Converter

The same speed reads 60 on a US speedometer and nearly 97 on a metric one, which is why mph versus km/h is the most common speed mix-up on the road. This converter also covers meters per second for physics and running, feet per second, knots for sailing and aviation, and Mach for anything approaching the speed of sound.

In Kilometers / hour
3.6km/h
1 m/s = 3.6 km/h
Speedometer
0 → 320 km/h
0801602403203.6km/h
Value
From
To
A knot isn't a mph
A knot is one nautical mile per hour (1.852 km/h), used at sea and in the air — slightly faster than a statute mile per hour.
Mach shifts with altitude
Mach isn't a fixed speed. This uses the sea-level speed of sound (343 m/s); sound travels slower in the colder air at cruising altitude, so true airspeed there is lower.
All units
Meters / second1
Kilometers / hour3.6
Miles / hour2.2369
Feet / second3.2808
Knots1.9438
Mach (at sea level)0.002915
Ask a follow-up
Uses your inputs above
3.6 in kilometers / hour. Want to try a variation?

The math

Reviewed 2026
Formula
Multiply or divide by the conversion factor to a base unit.

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Example: how speed is calculated

Step-by-step with default inputs

Suppose you put the default values into Speed Converter:

Value
1
From
Meters / second
To
Kilometers / hour

Plug those into the formula Multiply or divide by the conversion factor to a base unit. and the result is:

In Kilometers / hour
3.6km/h
Speed units and their conversion factors
UnitSymbolIn meters / second
Meters / secondm/s1
Kilometers / hourkm/h0.2778
Miles / hourmph0.447
Feet / secondft/s0.3048
Knotskn0.5144
Mach (at sea level)Mach343

Source: NIST official conversions

How does the speed converter work?

Speed Converter uses the formula shown in the math card and cites NIST official conversions. Inputs are validated for sensible ranges; results are computed client-side for instant feedback and do not leave your browser.

References: NIST official conversions.

Last reviewed July 2, 2026 · Editorial policy

Frequently asked questions

How do I convert mph to km/h?

Multiply by 1.609344, the number of kilometers in a mile. So 60 mph is about 96.6 km/h, and 100 km/h is about 62.1 mph.

How fast is a knot?

One knot is 0.514444 meters per second — about 1.151 mph or 1.852 km/h. It is one nautical mile per hour, the standard speed unit at sea and in aviation.

How fast is Mach 1 in mph?

About 767 mph. This converter pegs Mach 1 at 343 meters per second — the speed of sound in dry air at 20 °C, a common sea-level reference — which is roughly 1,235 km/h.

How accurate is this speed calculator?

The math is deterministic — the same inputs always produce the same output, and the formula is shown above. Accuracy of the answer for your situation depends on how well your inputs match reality and how well the formula models the question.

Why does Google show a slightly different conversion?

For most units the answer is identical to many decimal places. Differences usually come from currency rates (which fluctuate intraday — this tool shows the ECB's daily reference rates) or rounding. We display up to 4 decimals.

How do I share my result?

Hit Share at the top of the page. Every input you change is encoded in the URL, so a permalink reproduces exactly what you see. No account needed.