Speed Calculator: Find Speed, Distance or Time

Find the average speed, the distance travelled or the time taken from the other two, with the answer in several units.

Calculated from standard textbook formulas, with every step shown. The formulas are fixed, so the working does not need checking: what matters is the numbers you type in. Use these calculators only if you are competent to choose the inputs (loads, material strength, dimensions, supports) and check your units and assumptions. For learning and checking your own working: design and sign-off are for a qualified engineer. Drafting Central does not store the numbers you type.

How this calculator works

Choose which quantity you want to find.

Enter the other values in the units shown.

The calculator gives the answer with the formula, the substituted numbers, and the answer in other units.

Formulas used

  • v = \frac{d}{t}
  • d = v\,t
  • t = \frac{d}{v}

Worked example

With the default numbers in the calculator above:

  1. The formula, arranged to find the speed: speed = (distance) / (time)
  2. Put the values in (every value in its SI unit): speed = (100) / (10)
  3. The answer: speed: 10 m/s
  4. The same answer in other units: 36 km/h; 22.3694 mph; 19.4384 knots; 32.8084 ft/s

Change the numbers in the calculator to see the full working, every step, for your own case.

A second worked example

A different case, with these numbers: What do you want to find? Distance; Speed (leave it as it is if this is what you are finding) 10 m/s; Time (leave it as it is if this is what you are finding) 10 s.

  1. The formula, arranged to find the distance: distance = speed x time
  2. Put the values in (every value in its SI unit): distance = 10 x 10
  3. The answer: distance: 100 m
  4. The same answer in other units: 0.1 km; 0.0621371 miles; 328.084 feet; 0.0539957 nautical miles

Common questions

How do I find speed?

Divide the distance by the time. A car that goes 100 m in 10 s has a speed of 10 m/s, which is 36 km/h.

How do I find the time for a journey?

Divide the distance by the speed. 180 km at 90 km/h takes 2 hours.

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

Multiply by 3.6. To go from km/h to m/s divide by 3.6.

Related calculators

Got a question about this? Ask an engineering question and get a plain-language answer with references.

Further reading: Any school physics text (speed, distance and time).

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