Velocity Calculator

Quick Answer

Last updated: 3 November 2026 ·How we calculate this: v = d ÷ t and v = u + at

How This Velocity Calculator Works

Choose what you want to find. To get velocity, enter a distance and a time. To get distance, enter a velocity and a time. To get time, enter a distance and a velocity. For motion with steady acceleration, such as a falling object or a car speeding up, choose final velocity and enter the starting velocity, the acceleration and the time.

You can mix units: enter miles and hours, or feet and seconds. The calculator turns everything into meters and seconds, works out the answer, and then shows it in m/s, km/h, mph and ft/s, with every step.

How to Use the Velocity Calculator

1. Choose what to solve for: velocity, distance, time or final velocity.
2. Enter the values shown, such as distance and time.
3. Pick the unit for each value.
4. Press Calculate.
5. Read the answer in several units and follow the steps.

Core Formulas

• Average velocity: v = Δx ÷ Δt
• Distance: d = v × t
• Time: t = d ÷ v
• Final velocity: v = u + a × t
• Distance with acceleration: s = u × t + ½ × a × t²
• Without time: v² = u² + 2 × a × s

u is the initial velocity, a the acceleration and t the time. These motion equations only hold when the acceleration stays the same the whole time.

Key Terms

• Velocity: the rate of change of position, with a direction.
• Speed: how fast something moves, without a direction.
• Displacement: the straight-line change in position from start to end.
• Acceleration: the rate of change of velocity, in m/s².
• Initial velocity (u): the velocity at the start of the time period.

Worked Example

A car drives at a steady 60 mph for 2 hours. How far does it go?

• 60 mph = 60 × 0.44704 = 26.8224 m/s
• 2 hours = 7,200 seconds
• d = 26.8224 × 7,200 = 193121.28 m = 193.1213 km, which is 120 miles

Now a ball is dropped from rest. Gravity speeds it up by 9.81 m/s every second, so after 3 seconds v = 0 + 9.81 × 3 = 29.43 m/s, and it has fallen ½ × 9.81 × 3² = 44.145 m (ignoring air resistance).

Real-Life Examples

• Sprinting: 100 m in 9.58 s is 10.4384 m/s, or 23.35 mph.
• Road trips: 300 km at 100 km/h takes 3 hours.
• Falling objects: after 2 s of free fall from rest, a stone moves at 19.62 m/s.
• Braking: a car at 25 m/s slowing at −5 m/s² stops after 5 s and travels 62.5 m.

Velocity vs Acceleration

• Velocity: how fast position changes, in m/s.
• Acceleration: how fast velocity changes, in m/s².
• Link: a = (v − u) ÷ t, so you can find one from the other.

Common Speeds

Speed vs Velocity

• Speed is how fast something moves. It has no direction and is never negative.
• Velocity is speed in a given direction. It can be negative when an object moves backward.
• Average speed uses the total path length. Average velocity uses the straight-line change in position.
• A runner who does one full lap of a 400 m track has an average speed above zero but an average velocity of zero, because they finish where they started.

Velocity Units and Conversions

Scientists use meters per second. Road signs use km/h or mph, and engineers in the US often use feet per second. The conversions are exact because the foot and mile are defined in meters.

• 1 m/s = 3.6 km/h = 2.2369 mph = 3.2808 ft/s
• 1 mph = 0.44704 m/s = 1.609344 km/h
• 1 km/h = 0.2778 m/s

For quick mental maths, multiply m/s by about 2.24 to get mph, or by 3.6 to get km/h.

Common Mistakes to Avoid

• Mixing units. Kilometers and seconds give km/s, not km/h. Convert first or pick the units here.
• Confusing speed and velocity. A round trip has zero average velocity.
• Using v = d ÷ t with changing speed. It gives the average, not the speed at a moment.
• Forgetting the sign of acceleration. Slowing down needs a negative a.
• Using v = u + at when acceleration changes. The formula assumes it stays constant.

Frequently Asked Questions

References & Sources