Speed, Distance & Time Calculator

Speed, distance and time are linked by one formula: speed equals distance divided by time. If you know any two, you can find the third. This calculator works in kilometres and km/h or miles and mph, shows the working, converts decimal hours into hours and minutes, and draws a distance–time graph.

Try:

How to use the speed, distance & time calculator

  1. Choose whether to find speed, distance or time.
  2. Choose metric or imperial units.
  3. Enter the two values you know and press Calculate.

Formula

S=DTS = \frac{D}{T}
D=S×TD = S \times T
T=DST = \frac{D}{S}

Worked example: 150 km in 2.5 h

  • Find: Speed
  • Units: km, hours, km/h
  • Distance: 150
  • Time (hours, e.g. 2.5): 2.5

✓ Answer checked

S=60 km/hS = 60\text{ km/h}
0.511.522.520406080100120140160150 km after 2.5 h
Distance–time graph. The slope of the line is the speed, 60 km/h.
Step-by-step working (2 steps)

  1. Use the formula triangle Speed = distance ÷ time

    Speed = distance ÷ time. Cover the one you want to find.

    S=DTS = \frac{D}{T}

  2. Substitute

    Put in the values.

    1502.5=60\frac{150}{2.5} = 60
Formulas used
S=DTS = \frac{D}{T}
D=S×TD = S \times T
T=DST = \frac{D}{S}
How this was checked
  • ✓ 60 × 2.5 = 150, so all three values agree.

Assumes a constant (average) speed.

Frequently asked questions

How do I calculate speed?

Divide the distance by the time. 150 km in 2.5 hours is 150 ÷ 2.5 = 60 km/h.

How long does 210 km take at 70 km/h?

210 ÷ 70 = 3 hours.

Is this average speed?

Yes. The formula gives the average speed over the whole journey, assuming a steady pace.

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