Stopping Distance Calculator
🚗 Motion (kinematics). Use the Stopping distance formula to find stopping distance, speed, reaction time, braking deceleration: pick the value you want, type the others, and the answer updates as you go.
Thinking distance (before you brake) plus braking distance.
Pick the ○ next to the value you want to find, fill in the others, and it solves as you type.
What each letter means
| Quantity | Unit |
|---|---|
| Stopping distance | m |
| Speed | m/s |
| Reaction time | s |
| Braking deceleration | m/s² |
Worked example
Find the stopping distance when Speed = 20 m/s, Reaction time = 0.7 s, Braking deceleration = 6.5 m/s².
Using d = v treact + v²/2a: Stopping distance = 44.769 m.
Frequently asked questions
What is the formula for Stopping distance?
d = v treact + v²/2a. Thinking distance (before you brake) plus braking distance.
What do the letters stand for, and what units are used?
Stopping distance in m, Speed in m/s, Reaction time in s, Braking deceleration in m/s².
How do you calculate stopping distance?
Put the values into d = v treact + v²/2a. For example, with Speed = 20 m/s, Reaction time = 0.7 s, Braking deceleration = 6.5 m/s², stopping distance = 44.769 m.
Can I solve for a different value?
Yes. In the calculator above, pick the circle next to any value (stopping distance, speed, reaction time, braking deceleration) and fill in the others: it rearranges the formula for you.
