Speed Calculator
Please provide any two values in the fields below to calculate the third value in the speed distance time equation:
speed = distancetime
Speed Converter
The following converter converts between common units of speed.
Speed, Distance, and Time
What is speed?
Speed is defined as the change of position of an object over time — a measure of the rate at which an object travels over a given distance. In the International System of Units (SI), speed is measured in meters per second (m/s). Other units include kilometers per hour (km/h), miles per hour (mph), feet per second (ft/s), and many more. The unit that makes sense depends on what is being measured: it would not make sense to measure a snail's speed in meters per second, or a race car's in millimeters per second.
The relationship between speed, distance, and time
Speed, distance, and time are related by the formula speed = distance / time. This shows that:
- Speed increases if you cover more distance in the same amount of time, or cover a distance in a shorter period of time.
- Distance can be calculated if you know the speed and time: distance = speed × time.
- Time required to cover a distance can be found if you know the speed and distance: time = distance / speed.
Example:
Imagine you are riding a bicycle at a constant speed of 10 meters per second for 1 minute. How far will you have traveled? First convert the time into seconds (1 minute = 60 seconds), then use the distance formula:
distance = speed × time = 10 m/s × 60 s = 600 m. You will have traveled 600 meters in one minute.
Understanding this relationship is not just about solving physics problems; it helps in everyday situations — how long it will take to get to school at a certain speed, how fast you need to run to win a race, or how road speed limits are determined.
Common units of speed
| m/s | km/h | mph | kn | ft/s | |
|---|---|---|---|---|---|
| 1 meter/second [m/s] = | 1 | 3.6 | 2.236928 | 1.943844 | 3.280840 |
| 1 kilometer/hour [km/h] = | 0.277778 | 1 | 0.621369 | 0.539957 | 0.911344 |
| 1 mile/hour [mph] = | 0.44704 | 1.60935 | 1 | 0.868979 | 1.466672 |
| 1 knot [kn] = | 0.514444 | 1.852 | 1.150775 | 1 | 1.687810 |
| 1 foot/second [ft/s] = | 0.3048 | 1.09728 | 0.681816 | 0.592484 | 1 |
Examples of different speeds
| m/s | km/h | mph | |
|---|---|---|---|
| Average walking speed | 1.4 | 5 | 3.1 |
| Peak human running speed | 12.42 | 44.7 | 27.8 |
| Peak cheetah running speed | 33.53 | 120.7 | 75 |
| Average orbital speed of the Earth | 29,783 | 107,218 | 66,623 |
| Average orbital speed of the Sun | 251,000 | 904,000 | 561,000 |
| Speed of sound in air (sea level, 20°C) | 343 | 1,235 | 768 |
| Speed of light in vacuum | 299,792,458 | 1,079,252,848 | 670,616,629 |