Velocity Calculator

Find average velocity from distance and time, or final velocity from a starting speed, acceleration and time, with any units.

Average velocity

v = d ÷ t
Solve for
v
Average velocity
16.878km/h
2 sig figs: 17
≡
Same value in
4.688 m/s
10.49 mph · 15.38 ft/s · 468.8 cm/s
  1. Rearrange: v = d ÷ t
  2. Substitute: d = 42.195 km, t = 2.5 h (converted to SI units first).
  3. Result: v = 16.878 km/h, rounded to 2 significant figures because the least precise input has 2.

Final velocity with constant acceleration

v = u + a t
Solve for
v
Final velocity
13m/s
1 sig figs: 10
≡
Same value in
46.8 km/h
29.08 mph · 42.65 ft/s · 1,300 cm/s
  1. Rearrange: v = u + a t
  2. Substitute: u = 3 m/s, a = 2 m/s², t = 5 s (converted to SI units first).
  3. Result: v = 13 m/s, rounded to 1 significant figures because the least precise input has 1.

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Worked example

A marathon runner covers 42.195 km in 2 h 30 min. v = 42.195 ÷ 2.5 = 16.9 km/h = 4.69 m/s. A bike starting at 3 m/s and accelerating at 2 m/s² for 5 s reaches v = 3 + 2 × 5 = 13 m/s.

Frequently asked questions

What is the velocity formula?
Average velocity = displacement ÷ time (v = d ÷ t). With constant acceleration, final velocity v = u + at.
What is the difference between speed and velocity?
Speed is how fast (a scalar). Velocity is how fast and in which direction (a vector). Running a full lap of a 400 m track in 80 s is an average speed of 5 m/s but an average velocity of zero, since you end where you started.
How do I convert km/h to m/s?
Divide by 3.6 (1000 m ÷ 3600 s). 90 km/h = 25 m/s. The unit menus here convert automatically.
How do I find average velocity with different speeds?
Total displacement ÷ total time, not the average of the speeds. Driving 60 km at 60 km/h then 60 km at 30 km/h takes 3 h for 120 km: 40 km/h, not 45.