Stopping Distance Calculator

Your details

Speed of the vehicle at the moment the driver perceives a hazard.
mph
Time from perceiving a hazard to applying the brakes. AASHTO uses 2.5 s for road design.
Surface friction (mu) determines how quickly tires can transfer braking force. Dry asphalt ~0.7, wet ~0.4, snow ~0.2, ice ~0.1.
Slope of the road as a percentage. Positive = uphill (shorter stopping distance), negative = downhill (longer). Flat = 0.
%
Total stopping distanceLong stopping distance
303.9

Reaction distance + braking distance

Reaction distance132
Braking distance171.9
Braking time3.91s
Distance unitft
Reaction distance132
Braking distance171.9

Total stopping distance: 303.9 ft at 60 mph.

  • At 60 mph on a dry road, you travel 132.0 ft before your brakes even engage.
  • The brakes then need another 171.9 ft and about 3.9 seconds to stop the vehicle.
  • Reaction distance makes up 43% of your total stopping distance - alertness has a major effect.

Next stepTo reduce stopping distance: slow down (distance scales with the square of speed), stay alert, maintain tires and brakes, and increase following distance on wet or slippery surfaces.

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