Physics
Speed from distance and time
The standard form. Convert distance and time to matching units, then divide.
The Formula
s = d / t
The standard form. Convert distance and time to matching units, then divide.
| Symbol | Meaning | Unit | Notes |
|---|---|---|---|
| d | Distance travelled | length | Measured along the path, in kilometres, metres or miles. |
| t | Time taken | time | In decimal hours when the speed is wanted in kilometres per hour. |
| s | Speed | length per time | Distance divided by time; a rate, never negative. |
What Each Symbol Means
dlength
Distance travelled
Measured along the path, in kilometres, metres or miles.
ttime
Time taken
In decimal hours when the speed is wanted in kilometres per hour.
slength per time
Speed
Distance divided by time; a rate, never negative.
See It Worked With Real Numbers
A formula on its own does not tell you which number goes where. The how to calculate speed page applies this equation to a concrete case, shows every intermediate step, and names the mistakes that produce a wrong answer even when the algebra is right.
Where This Formula Appears
This equation is the working core of How To Calculate Speed, filed under Science. Every number the guide produces comes from substituting into this one line.