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Speed Distance Time online

Calculate speed, distance, or time given the other two values

Speed Distance Time Calculator logo
by
CHUNKY
MUNSTER
Leave one field blank — it will be calculated for you:

How to Use the Speed Distance Time Calculator

  1. Pick which value you want to calculate (speed, distance or time).
  2. Enter the other two values and choose their units.
  3. The missing value appears live in the highlighted field.
  4. Switch units at any time — the answer rescales automatically.

The SDT triangle — speed equals distance over time — is the first physics formula most people memorise, and it's the only one you need for the vast majority of journey, pace and rate questions. This calculator lets you fill in any two of the three and computes the third, switching units (km, miles, metres; hours, minutes, seconds) on the fly.

How the Speed Distance Time Calculator Works

It assumes constant speed for the whole interval, which is what "average speed" means. For real journeys with stops, traffic and acceleration, the calculated speed is the equivalent steady speed that would have produced the same distance in the same time.

Frequently Asked Questions

Which formula does this use?

The classic SDT triangle: speed = distance ÷ time. Rearranged, distance = speed × time and time = distance ÷ speed. The calculator picks the right rearrangement based on which field you leave empty.

How do I convert km/h to m/s?

Divide by 3.6 (or multiply by 5/18). 100 km/h = 27.78 m/s. The calculator does this automatically when you switch the speed unit, so you never have to do it by hand.

Does this give average speed or instantaneous speed?

Average speed — total distance divided by total time. For instantaneous speed (the speedometer reading) you need calculus or a real instrument; the SDT formula assumes constant speed across the whole journey.

Can I use it for non-travel scenarios?

Yes — the maths is the same for any constant-rate process: data transfer (MB/s, file size, time), running pace (min/km), or even labour rate (units/hour). Just pick units that make sense and read the result.

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