ConverterHub

Speed–Distance–Time Calculator

How do I calculate speed, distance and time?

Enter any two; the third is calculated

How it is calculated

The tool uses distance = speed × time and its rearrangements speed = distance / time and time = distance / speed. Fill in exactly two of the three fields and leave the third blank; the tool solves for the blank one. If you fill one or all three, or if the divisor is zero or negative, it asks for exactly two valid values. The units are fixed: distance in kilometres, speed in km/h and time in hours, and the result shows all three. Time comes out as a decimal number of hours, so 2.50 h means 2 hours 30 minutes, not 2 hours 50 minutes. It assumes constant speed throughout, so stops and traffic are not included.

Worked example

A trip is 150 km at a constant 60 km/h; the time field is left blank. Time = distance / speed = 150 / 60 = 2.5 hours. The tool shows 150.00 km, 60.00 km/h and 2.50 h. In hours and minutes this is 2 h plus 0.5 × 60 = 30 min, so 2 hours 30 minutes.

Try this example →

Common mistakes

  • Reading 2.50 h as 2 hours 50 minutes; the decimal part is a fraction of an hour (0.5 h = 30 min).
  • Entering speed in m/s or miles per hour while the tool works in km/h.
  • Typing minutes into the time field, which expects hours (45 minutes is 0.75).
  • Filling all three fields, or only one, instead of exactly two.
  • Using an average speed that ignores stops, so the real journey takes longer than calculated.

About this calculator

This calculator uses the fixed relationship between speed, distance and time — distance equals speed multiplied by time — to solve for whichever one of the three values you don't already know, as long as the other two are entered. Because the formula can be rearranged three different ways, the same tool works whether you're missing the speed, the distance, or the time.

It is a staple of physics and math coursework, where students plug in two known values to find the third and check their manual algebra, but it also solves everyday practical questions: estimating how long a trip will take given an expected average speed and known distance, figuring out how fast you'd need to travel to cover a distance within a deadline, or calculating the distance covered on a journey when you only know your speed and how long you traveled.

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