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Stopping Distance Calculator

Reaction plus braking distance for any speed, road condition and driver alertness.

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All Running costs tools →
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Stopping Distance Calculator is free to use as often as you like, directly from this page. Its place is under Running costs; Headlight Beam Distance Calculator and Engine Compression Ratio Calculator answer the questions closest to this one.

How to use it

  1. Open the tool — no signup or install needed.
  2. Enter your input or adjust the available options.
  3. Get your result instantly, then copy or download it.

Frequently asked questions

What does Stopping Distance Calculator do?

Reaction plus braking distance for any speed, road condition and driver alertness.

When would I actually use this?

Deciding between two cars, or between keeping one and replacing it: fuel or charging, insurance, depreciation and what a kilometre really costs.

What is the most common mistake?

Comparing on fuel alone. Depreciation is usually the largest line in the first years and dwarfs the difference in consumption between two comparable cars.

How is Stopping Distance Calculator different from Headlight Beam Distance Calculator?

They sit next to each other but answer different questions. Headlight Beam Distance Calculator: how far your low beams reach from their aim angle and mounting height — and whether you outrun them. Pick whichever matches what you're starting from — both are free.

Is there a tool for the next step?

Engine Compression Ratio Calculator is the closest one after this: Static compression ratio from bore, stroke and chamber volume, with gasket and piston corrections.

What else is worth having open alongside it?

RV Loan Calculator and Trailer Tongue Weight Calculator — they come up in the same task often enough to be worth a second tab.

Where do the figures come from?

The arithmetic is exact for the prices and consumption you enter. Manufacturer figures are measured on a standard cycle and real-world consumption is routinely 10% to 25% higher.

Further reading

All guides →
ExplainerStopping Distance Is Mostly Not BrakingTotal stopping distance is two distances added together, and they follow different laws — one grows with speed, the other with speed squared. That single fact explains why doubling your speed roughly triples the distance.ExplainerHeadlight Aim and How Far You Can Actually SeeA dipped beam is aimed downward by a fraction of a degree, so its reach on flat road is a single division. Do it and you find that at motorway speed the beam is shorter than the stopping distance — and that a loaded boot can throw the whole calculation away.ExplainerWhere the Weight Sits Decides How the Car BehavesTwo axle weights and a wheelbase give you the exact position of a car's centre of gravity. From there the arithmetic keeps going: how much weight braking moves forward, why the rear axle is the one that runs out of grip, and why a load behind the rear axle takes weight off the front.ExplainerTyre Tread Depth: the Legal Limit Is Not the Safe LimitThe legal minimum exists to define an offence, not to describe a safe tyre. Tread does one job — getting water out of the contact patch — so its effect is near zero in the dry and decisive in the wet. Here is what the numbers say, and how to measure your own.ExplainerCornering Twice as Fast Needs Four Times the GripA 1,500 kg car on a 50-metre bend needs 5,880 N of sideways force at 14 m/s and 23,520 N at 28. Halving the radius instead only doubles it.ExplainerA Car Brakes Three Times Harder Than It AcceleratesReaching 27 m/s from rest in ten seconds is 2.7 m/s². Stopping from the same speed in three seconds is −9 m/s² — a third of gravity against nine tenths of it.