How to use this calculator
- Enter the requested journey or vehicle details.
- Select the matching units and options.
- Choose Calculate to see the estimate and supporting values.
- Change any value and calculate again to compare scenarios.
How the calculation works
For MPH, the tool interpolates between Highway Code reference values. KM/H is converted to MPH first.
Formula: Total stopping distance = thinking distance + braking distance, interpolated from reference speeds.
Worked example
At 60 MPH, the Highway Code reference is 18 m thinking distance plus 55 m braking distance: 73 m total.
What can affect the result?
Road surface, rain, ice, tyres, brakes, reaction time, vehicle load and gradient can greatly increase stopping distance.
Road-safety guidance
The baseline stopping distances use the UK Highway Code table. Conditions, attention, tyres and brakes may make actual distances much longer. Read Highway Code rule 126.
Frequently asked questions
Is this a guaranteed stopping distance?
No. It is an educational estimate using reference values.
What source is used?
Current UK Highway Code stopping-distance reference material on GOV.UK.
