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Speed Distance Time Calculator and Formula

The speed formula is speed = distance ÷ time, or v = s/t, with speed in m/s, distance in metres and time in seconds. Rearranged, distance travelled = speed × time (s = vt) and time = distance ÷ speed.

Speed formula: v = s/t

Speed, distance, time
v = st
v = sts = v·tt = sv
Average speed
vav = s1 + s2t1 + t2
v
speed, m/s
s
distance, m
t
time, s
vav
average speed, m/s
s1
distance, first part, m
t1
time, first part, s
s2
distance, second part, m
t2
time, second part, s

Convert every value to SI units (m, s, kg, A, V, Ω) before substituting into the formula. The calculator does this for you and shows the conversion as a step.

60 km/h
vspeed
60 km/h
speed: 60 km/h
A car covers 120000 m in 7200 s, so its speed is 16.7 m/s. On the distance–time graph beside it, a steeper line means a higher speed.

Step-by-step solution

  1. Formulav = st
  2. In SI unitss = 120 km = 120000 m
  3. t = 2 h = 7200 s
  4. Substitutev = 120000 m7200 s
  5. Answerv ≈ 16.7 m/s = 60 km/h

Speed, distance and time examples

  1. Example 1

    A cyclist rides one lap of a 400 m track in 50 s. Calculate her average speed in m/s.

    Given:s = 400 mt = 50 s
    1. Formulav = st
    2. Substitutev = 400 m50 s
    3. Answerv = 8 m/s

  2. Example 2

    A student walks to school at a steady speed of 1.5 m/s, and the walk takes 20 min. How far does she walk? Give your answer in metres.

    Given:v = 1.5 m/st = 20 min
    1. Formulas = v·t
    2. In SI unitst = 20 min = 1200 s
    3. Substitutes = 1.5 m/s · 1200 s
    4. Answers = 1800 m

  3. Example 3

    A coach travels 120 km along a motorway at an average speed of 80 km/h. How long does the journey take, in hours?

    Given:s = 120 kmv = 80 km/h
    1. Formulat = sv
    2. In SI unitsv = 80 km/h = 22.22 m/s
    3. s = 120 km = 120000 m
    4. Substitutet = 120000 m22.22 m/s
    5. Answert = 5400 s = 1.5 h

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What does the speed formula mean?

Speed tells you how much distance is covered in each unit of time. At GCSE it is written as distance travelled = speed × time, or s = vt, where s is the distance in metres, v is the speed in metres per second and t is the time in seconds. The same relationship gives speed (v = s/t) or time (t = s/v), so if you know any two of the three quantities you can find the third.

The formula assumes a constant speed, or it gives the average speed if the speed changes along the way. For a journey in several parts, average speed = total distance ÷ total time, which is not the same as the mean of the speeds. Speed is a scalar; velocity is speed in a given direction, so it is a vector. On a distance–time graph the gradient of the line is the speed: the steeper the line, the faster the object.

An everyday picture: a train that covers 300 km in two hours has an average speed of 150 km/h, even though it sped up, slowed down and stopped at stations along the way. Typical speeds worth knowing for GCSE are about 1.5 m/s for walking, 3 m/s for running and 6 m/s for cycling.

Common mistakes

  • Mixing units, such as dividing kilometres by seconds. Convert to m and s, or keep km and h together.
  • Converting km/h to m/s the wrong way: divide by 3.6 to go from km/h to m/s (72 km/h = 20 m/s) and multiply by 3.6 to go back.
  • Treating minutes as a decimal of an hour: 1 h 30 min is 1.5 h, not 1.3 h.
  • Finding average speed by averaging the speeds of each part. Divide the total distance by the total time instead.
  • Putting time on top: speed is distance ÷ time, never time ÷ distance.

Related formulas

AccelerationSUVAT equationsKinetic energyAll physics equations

Frequently asked questions

Speed = distance ÷ time, written v = s/t. At GCSE it is usually given as distance travelled = speed × time (s = vt).

Multiply the speed by the time: s = v × t. Make sure the units match, so a speed in m/s with a time in seconds gives a distance in metres.

Divide by 3.6, because one kilometre per hour is 1000 m in 3600 s. For example, 36 km/h is 10 m/s.

Divide the total distance by the total time for the whole journey, including any stops. Taking the mean of the speeds for each part only works if each part lasts the same time.

Speed is a scalar: it has size only. Velocity is a vector: it is speed in a given direction, so two cars at the same speed travelling in opposite directions have different velocities.