Speed Converter

How the converter works

Each unit is expressed as an exact number of metres per second. A kilometre per hour is 1,000 m in 3,600 s, which is 1/3.6 m/s. A mile per hour is 1,609.344 m in 3,600 s, exactly 0.44704 m/s. A foot per second is 0.3048 m/s, and a knot — one nautical mile per hour — is 1,852/3,600 ≈ 0.514444 m/s. The value is multiplied by the source factor and divided by the target factor.

result = value × (m/s per source unit) ÷ (m/s per target unit)
pace (min/km) = 1,000 ÷ speed in m/s ÷ 60

Worked examples

Example 1: 60 mph in km/h

60 × 0.44704 = 26.8224 m/s, then × 3.6 = 96.56064 km/h.

Example 2: 100 km/h in mph

100 ÷ 3.6 = 27.7778 m/s, ÷ 0.44704 = 62.137119 mph.

Example 3: a 10 km/h jog as pace

10 km/h is 2.7778 m/s, giving a pace of 1,000 ÷ 2.7778 ÷ 60 = 6:00 per km and 9:39 per mile.

Example 4: a 25-knot boat

25 × 0.514444 = 12.8611 m/s = 46.3 km/h or 28.77 mph.

How to read the result

The headline is the speed in the chosen unit, the formula line shows the conversion multiplier, and the table gives the speed in all five units. Below the table, pace is shown as minutes and seconds per kilometre and per mile — slower speeds give larger pace numbers, which is why a "faster" pace is a smaller figure.

Speed versus pace

Speed is distance per unit time; pace is time per unit distance. They are reciprocals, so they do not change in proportion: improving from 6:00 to 5:00 per km is a 20% faster speed (10 to 12 km/h), but a 16.7% shorter pace. Runners plan races by pace because it maps directly onto split times — a 5:00/km pace gives a 50-minute 10K. Cyclists, drivers and pilots use speed. When converting a pace from minutes per mile to minutes per kilometre, divide by 1.609344.

Common uses

Drivers convert speed limits and speedometer readings when travelling between countries that use mph and km/h. Runners and walkers convert treadmill speeds into pace. Sailors and pilots use knots, while weather services report wind in knots, mph, km/h or m/s depending on the country. Physics homework and engineering specifications use metres per second, and sports science often quotes sprint and ball speeds in m/s or ft/s. For reference, the speed of sound in dry air at 20 °C is about 343 m/s, roughly 1,235 km/h or 767 mph.

Limits

Results are rounded to six decimals for display. Speeds near the speed of light are beyond the scope of these simple formulas. Mach numbers are not offered because the speed of sound changes with temperature and altitude, so a fixed factor would be misleading. To find a travel time from a speed and distance, divide the distance by the speed, and use the time converter to express the answer in convenient units.

Everyday reference speeds

A few benchmarks help you sense whether a converted figure is plausible. Walking pace is around 5 km/h (3.1 mph, about 1.4 m/s). A recreational jog is 8 to 10 km/h, and elite marathon pace is just over 20 km/h. Urban cycling usually sits between 15 and 25 km/h. Common road limits are 30 or 50 km/h in towns and 100 to 130 km/h on motorways, while US limits are posted in mph: 25 to 35 mph in towns and 55 to 75 mph on highways. A commercial jet cruises at roughly 900 km/h (about 490 knots).

Average speed over a journey

Average speed is total distance divided by total time, not the average of the speeds in each part. Driving 60 km at 60 km/h and another 60 km at 120 km/h takes 1 hour plus 30 minutes, so the average is 120 km ÷ 1.5 h = 80 km/h, not 90 km/h. Converting units does not change this rule, but it is worth applying before you convert. To find the time for a trip, divide the distance by the speed, using matching units: 250 miles at 62 mph takes about 4.03 hours, which the time converter can express as 4 hours and 2 minutes.

Wind speeds

Weather services in different countries report wind in different units, and the Beaufort scale ties them to observable effects. A fresh breeze, Beaufort force 5, is about 17 to 21 knots (roughly 30 to 39 km/h); force 8, a gale, is 34 to 40 knots; hurricane force, 12, begins at 64 knots, about 118 km/h or 74 mph. Gusts can be much stronger than the sustained speed.