Speed, Distance and Time Calculator
Solve s = d ÷ t for average speed, distance or time, with per-field units.
What is Speed / Distance / Time?
Average speed is distance divided by time, and the same relationship rearranged answers the other two questions — how far you got, or how long it took. 'Average' is the important word: a trip with stops has one average speed and many instantaneous ones, and this calculation gives the former.
How it works
s = d ÷ t, solved for whichever field is blank, with each value converted from the unit you chose into metres, seconds and metres per second. The rearranged form used is shown with your numbers in it. Units may be mixed freely between fields — kilometres for distance, minutes for time — because the conversion happens before the division.
- Enter what you know. Every field recalculates as you type — there is no submit button. Leave the quantity you want blank and the page solves for it.
- Read the answer and the working. The result appears above the fold; underneath it is the formula with your numbers substituted, so the arithmetic can be checked rather than trusted.
- Check the units and the size. Units are shown on every value and selectable per field, so a result in kJ, kPa or km/h is converted rather than assumed. Sanity-check the magnitude against a known landmark such as 1 g/cm³ for water.
Examples
A textbook problem with a known answer
Every tool here is checked against standard example problems — the molar mass of C6H12O6 is 180.16 g/mol, and free fall from 20 m takes about 2.02 s at g = 9.8 m/s².
A result you want to reason backwards from
Leave the quantity you already know blank instead: given the final answer, most tools recover the starting value — the mass needed for a target concentration, or the height a fall must have had.
Common mistakes
Forgetting that a formula is only as good as its subscripts
H2O and H2O2 are different compounds. The formula field shows its parse — element by element — so a mis-typed subscript is visible before it reaches the arithmetic.
Mixing units in the middle of a calculation
The most common source of a wrong answer is a value in grams next to a formula expecting kilograms, or Celsius next to a gas constant expecting kelvin. This category converts on the way in and labels what it used.
Frequently asked questions
What is the average speed if I drive 100 km in 1 hour 15 minutes?
80 km/h. Convert the time to 1.25 hours and divide — 100 ÷ 1.25 = 80. The calculator takes hours and minutes separately or km/h directly.
Is average speed the same as average velocity?
No. Speed has no direction; velocity does. A round trip back to the start has an average velocity of zero and a non-zero average speed, because velocity depends on displacement rather than distance travelled.
Why is the answer in m/s when I entered km/h?
The unit selector on each field decides. Each answer is reported in the unit chosen for that field's own selector, so set the speed unit to km/h and the answer comes back in km/h.