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Convert km/h, m/s, mph, knots and ft/s, solve for speed, distance or time, and see the equivalent running pace in minutes per kilometre.
Speed, Distance & Time
Hours, minutes, seconds
| Unit | Value |
|---|
One relationship, rearranged three ways. The calculator above asks which you want so it is never guessing.
The only real trap is units. If distance is in kilometres and time in hours, speed comes out in km/h. Mix minutes with kilometres and you get km per minute, which is rarely what anyone wants — so the calculator takes time as hours, minutes and seconds and does the arithmetic itself.
| Example | Working | Result |
|---|---|---|
| 300 km in 3 hours | 300 ÷ 3 | 100 km/h |
| 100 km/h for 2h 30m | 100 × 2.5 | 250 km |
| A marathon at 10 km/h | 42.195 ÷ 10 | 4h 13m 10s |
| Conversion | Multiply by | Shortcut |
|---|---|---|
| km/h → m/s | ÷ 3.6 | The one worth memorising |
| m/s → km/h | × 3.6 | |
| km/h → mph | × 0.621371 | Roughly × 0.6 |
| mph → km/h | × 1.609344 | Roughly × 1.6 |
| knots → km/h | × 1.852 | Exact by definition |
| ft/s → m/s | × 0.3048 | Exact by definition |
| km/h | m/s | mph | knots |
|---|---|---|---|
| 10 | 2.78 | 6.21 | 5.40 |
| 50 | 13.89 | 31.07 | 27.00 |
| 60 | 16.67 | 37.28 | 32.40 |
| 100 | 27.78 | 62.14 | 54.00 |
| 110 | 30.56 | 68.35 | 59.40 |
| 130 | 36.11 | 80.78 | 70.19 |
Runners and cyclists rarely talk in km/h. They use pace — minutes per kilometre — which is speed turned upside down.
| Speed | min/km | min/mile | 5 km takes | Marathon takes |
|---|---|---|---|---|
| 6 km/h (brisk walk) | 10:00 | 16:05 | 50:00 | 7h 02m |
| 8 km/h | 7:30 | 12:04 | 37:30 | 5h 16m |
| 10 km/h | 6:00 | 9:39 | 30:00 | 4h 13m |
| 12 km/h | 5:00 | 8:03 | 25:00 | 3h 31m |
| 14 km/h | 4:17 | 6:54 | 21:26 | 3h 01m |
| 17 km/h | 3:32 | 5:41 | 17:39 | 2h 29m |
The calculator shows pace alongside the speed conversions whenever the figure is in a plausible human range. Above about 45 km/h it stops, because "0:33 min/km" for a car on the highway is arithmetically true and completely useless.
| Limit | mph | m/s | Where |
|---|---|---|---|
| 40 km/h | 24.9 | 11.1 | School zones, shared zones |
| 50 km/h | 31.1 | 13.9 | Default urban limit in most states |
| 60 km/h | 37.3 | 16.7 | Main urban roads |
| 80 km/h | 49.7 | 22.2 | Outer urban, some rural |
| 100 km/h | 62.1 | 27.8 | Rural default in most states |
| 110 km/h | 68.4 | 30.6 | Freeways and highways |
| 130 km/h | 80.8 | 36.1 | Some Northern Territory highways |
Limits are set by each state and territory, so they vary — the default urban limit is 50 km/h in most places, and rural defaults differ. Always follow the posted signs.
This is the speed calculation with real consequences, and the reason it surprises people is that braking distance rises with the square of speed.
| Speed | Reaction (1.5 s) | Braking | Total |
|---|---|---|---|
| 40 km/h | 17 m | 9 m | 26 m |
| 50 km/h | 21 m | 15 m | 36 m |
| 60 km/h | 25 m | 21 m | 46 m |
| 80 km/h | 33 m | 38 m | 71 m |
| 100 km/h | 42 m | 59 m | 101 m |
| 110 km/h | 46 m | 72 m | 118 m |
| Thing | Approximate speed |
|---|---|
| Walking | 5 km/h |
| Brisk walk | 6.5 km/h |
| Recreational cycling | 20 km/h |
| Usain Bolt, peak | ~44 km/h |
| Suburban train | 60–110 km/h |
| Commercial aircraft, cruise | ~900 km/h (485 knots) |
| Speed of sound at sea level | ~1,235 km/h |
| Speed of light | 1,079,252,849 km/h |
Both worlds work in knots, and aviation adds Mach once you are high and fast enough for it to matter.
| Craft | Typical cruise | km/h | Mach (at altitude) |
|---|---|---|---|
| Light aircraft (Cessna 172) | ~120 knots | ~220 | — |
| Turboprop regional | ~280 knots | ~520 | — |
| Passenger jet | ~485 knots | ~900 | ~0.85 |
| Business jet | ~450 knots | ~830 | ~0.80 |
| Concorde (retired) | ~1,150 knots | ~2,130 | ~2.0 |
| Vessel | Typical speed | km/h |
|---|---|---|
| Recreational sailboat | 6–10 knots | 11–19 |
| Container ship | 20–25 knots | 37–46 |
| Cruise ship | 20–24 knots | 37–44 |
| Ferry (fast catamaran) | 30–40 knots | 56–74 |
| Tugboat | 10–14 knots | 19–26 |
How do you calculate speed?
Divide distance by time. Three hundred kilometres in three hours is 100 km/h. Keep the units consistent — kilometres with hours gives km/h, while metres with seconds gives m/s.
How do I convert km/h to m/s?
Divide by 3.6, so 100 km/h is 27.78 m/s. The factor comes from 3,600 seconds in an hour and 1,000 metres in a kilometre. Going the other way, multiply m/s by 3.6.
How many km/h is 1 mph?
Exactly 1.609344 km/h, since the mile is defined in metric terms. So 60 mph is 96.56 km/h and 100 km/h is 62.14 mph. For rough work, multiply mph by 1.6 or km/h by 0.6.
What is a knot?
One nautical mile per hour, or exactly 1.852 km/h. A nautical mile is one minute of latitude, which makes knots convenient for navigation because distance can be read straight off a chart's latitude scale. Aviation and shipping use them worldwide.
What is running pace?
Minutes per kilometre — the inverse of speed. Divide 60 by your speed in km/h, so 10 km/h is a 6:00 min/km pace. A lower pace number means you are running faster, which is the opposite of how speed works and a common source of confusion.
What pace do I need for a sub-4-hour marathon?
About 5:41 per kilometre sustained across all 42.195 km, which is roughly 10.6 km/h. A sub-3-hour marathon needs about 4:15 per kilometre. Both assume an even pace, and most runners plan slightly faster early splits to allow for slowing later.
How long does it take to drive 300 km?
At 100 km/h it is three hours of driving. Real journeys take longer once you allow for lower speed limits through towns, roadworks, traffic and rest breaks — which are essential on long Australian drives.
Why does stopping distance increase so much with speed?
Because braking distance depends on kinetic energy, which rises with the square of speed. Doubling your speed doubles your reaction distance but quadruples the braking distance. Going from 50 to 60 km/h adds only ten to the speedo but roughly ten metres to your total stopping distance.
What is the average speed if I drive out at 60 and back at 100?
About 75 km/h, not 80. You spend more time at the slower speed, so the average must be weighted by time rather than simply added and halved. The correct approach is total distance divided by total time.
What is the default speed limit in Australia?
Fifty km/h in built-up areas in most states and territories, and 100 km/h on rural roads, with freeways commonly signed at 110. Limits are set by each jurisdiction and vary, and some Northern Territory highways are signed at 130. Always follow the posted signs.
How fast is the speed of sound?
About 1,235 km/h at sea level in dry air at 20 °C, or roughly 343 m/s. It varies with temperature — sound travels faster in warmer air — which is why aircraft speeds are given as a Mach number relative to local conditions rather than a fixed figure.
How fast is Mach 1?
It depends on air temperature, so there is no single answer. At sea level on a standard 15 °C day it is about 1,225 km/h, but at typical airliner cruise altitude where the air is near −56 °C it drops to around 1,062 km/h — a 15% difference. This is why aircraft speeds are given as a Mach number rather than a fixed figure, and why the converter above asks which reference condition you mean.
How fast do passenger aircraft fly?
Around 485 knots or 900 km/h at cruise, which is roughly Mach 0.85 at altitude. Light aircraft such as a Cessna 172 cruise nearer 120 knots or 220 km/h. Aviation quotes speed in knots worldwide, and Mach becomes the more useful measure once an aircraft is fast enough for compressibility to matter.
Why do ships and aircraft use knots?
Because a nautical mile is one minute of latitude, so distance can be read straight off a chart's latitude scale. That made knots the practical unit for navigation long before electronic systems, and both ICAO and IMO kept them as the standard. One knot is exactly 1.852 km/h.
What is the SI unit of speed?
Metres per second. Kilometres per hour is more convenient for road use and is what Australian signs and speedometers show, but every physics formula expects m/s — which is why dividing by 3.6 is such a frequently used step.
Speed conversion is simple arithmetic with one shortcut worth memorising — km/h to m/s is a division by 3.6 — and one relationship worth respecting, which is that stopping distance grows with the square of speed rather than in step with it.
If you run, pace rather than speed is probably the number you want, and it is the inverse: lower is faster.
For other measurement types, the unit converter covers ten categories, and the length converter handles distances including a steps-to-distance option.