How do I convert mph to km/h?

Multiply miles per hour by 1.609344 to get kilometres per hour. For example, 60 mph × 1.609344 = 96.56 km/h. Enter 60 in the mph field and the km/h card fills in automatically.

How do I convert km/h to m/s?

Divide kilometres per hour by 3.6, because 1 km/h equals 1000 metres over 3600 seconds. So 100 km/h ÷ 3.6 = 27.78 m/s.

What is a knot and how does it relate to mph?

A knot is one nautical mile per hour, and a nautical mile is defined as exactly 1852 metres. That makes 1 knot equal to about 1.15078 mph or 1.852 km/h, which is why aircraft and ships read slightly higher in km/h than in knots.

Mach number is your speed divided by the local speed of sound. This tool uses the standard sea-level value of 340.29 m/s (ISA, 15 °C dry air), so Mach 1 is about 1225 km/h, 761 mph or 661 knots at the surface.

Why does the Mach figure change with altitude in real life?

The speed of sound depends on air temperature, which drops as you climb. Colder air carries sound more slowly, so the same true airspeed is a higher Mach number high up than near the ground. The converter assumes sea-level conditions for a consistent reference.

Is my data sent anywhere?

No. Every calculation runs entirely in your browser using plain arithmetic. Nothing is uploaded, logged or stored on a server, and your last entry is saved only on this device.

Speed Converter — Gera Tools

A fast, accurate speed converter that handles every unit you are likely to meet in driving, running, sailing, aviation and physics: metres per second (m/s), kilometres per hour (km/h), miles per hour (mph), knots, feet per second (ft/s) and Mach. Unlike a two-box converter, this tool shows the same speed in all six units at once, and you can type into any field to drive the rest — handy when you are checking a wind speed in knots against a road limit in mph, or sanity-checking a cruise speed in km/h against Mach.

How it works

Every unit is defined against a single canonical base, metres per second, using the exact international definitions so the maths cannot drift. One mile is exactly 1609.344 metres, so 1 mph is 0.44704 m/s. One nautical mile is exactly 1852 metres, so 1 knot is 0.514444 m/s. One foot is exactly 0.3048 metres, so 1 ft/s is 0.3048 m/s. Kilometres per hour are simply 1000 metres over 3600 seconds, giving the familiar rule m/s = km/h ÷ 3.6. Mach uses the standard-atmosphere sea-level speed of sound, 340.29 m/s.

To convert, the tool turns your input into m/s, then divides back out into every other unit. That single round trip means all six readings always agree to full precision. Type 60 in the mph field and you instantly get 96.56 km/h, 26.82 m/s, 52.14 knots, 88 ft/s and Mach 0.0788. Change the input unit with the “Next unit” button, or just start typing in a different card — the highlighted card marks whichever unit you last edited.

Worked example

Suppose an aircraft is cruising at 900 km/h and you want to know its Mach number and its speed in knots. Enter 900 in the km/h field. The grid shows 250 m/s, 559.23 mph, 485.96 knots, 820.21 ft/s and Mach 0.7347 (at sea-level reference). Because Mach depends on temperature, the same 900 km/h would read as a higher Mach number at altitude where the air is colder — useful context the reference note explains.

Conversion reference

km/h	m/s	mph	knots	ft/s	Mach
1	0.28	0.62	0.54	0.91	0.0008
50	13.89	31.07	27.00	45.57	0.0408
100	27.78	62.14	53.996	91.13	0.0816
120	33.33	74.56	64.79	109.36	0.0980
500	138.89	310.69	269.98	455.67	0.4081
1000	277.78	621.37	539.96	911.34	0.8163

Key fixed factors: 1 mile = 1609.344 m, 1 nautical mile = 1852 m, 1 foot = 0.3048 m, and m/s = km/h ÷ 3.6. Mach assumes a sea-level speed of sound of 340.29 m/s. Every figure here is generated by the same in-browser arithmetic the live tool uses, so the table and the converter never disagree.

Everything is calculated in your browser — no numbers are uploaded or stored.