Calculating Your Braking Distance: Learn Your Stopping Distance

Do a road test to check how long it takes you to stop.


While you might not think of your braking distance every time you drive across town, one day you will need to slow down as fast as possible. All sorts of things can go wrong, and highway driving is deceptively fast. Other drivers can drift into your lane, animals can wander in front of you—the potential for danger is very real. The following driving safety tips will help you understand what kind of braking distance you can expect from your vehicle and how speed affects how long it will take you to bring your car to a complete stop.

First, let's define a few terms:

  1. Braking Distance: Braking distance is the distance your car travels after the brakes have been applied. According to auto industry standards for deceleration, if you are traveling at 70 miles per hour, it takes 315 feet to stop an average car once the brakes have been applied.
  2. Stopping Distance: The term stopping distance takes into account the distance you travel before you hit the car brake system (reaction distance) plus the distance you travel while the brakes slow you down (braking distance). This might not seem like a big difference, but if you're moving down an interstate highway at 70 mph, you're passing 100 feet of asphalt every second.
  3. Reaction Distance: If it takes you 1.5 seconds at 70 mph to even realize that a problem exists, you've already traveled about 150 feet. That means you've passed half a football field before the brakes have even begun to kick in. Since half a football field is a long distance to cover before you even start slowing down, we include reaction distance in the discussion.
  4. Other Variables: Braking distance varies depending on many variables, including your reaction time, your speed, the weight of the car, road conditions, braking efficiency, and friction between the road surface and your tires. You can see that many things can go wrong when you need to brake in a hurry. That is why most traffic experts advise you to stay three to four seconds behind the car in front of you.

There are two times when you should be especially interested in calculating your braking distance:

Road Test: You can determine your braking distance on a test track or empty parking lot.

  • Make sure nobody is nearby—it's best to avoid having a real emergency braking situation.
  • Ensure that the area is empty before you start your road test.
  • Set up cones or use a landmark to indicate the point at which you will begin braking.
  • Bring a measuring tape or similar device to measure 10-foot intervals.
  • When you're ready, test your braking distance at 10, 20, 30, and 40 miles per hour. For safety's sake, don't test your braking distance at higher speeds, and keep the car going straight until you are stopped.

While Driving: Since you probably aren't interested in calculating all of those numbers while you drive, you might prefer to recall the three-second rule. Stay at least three seconds behind any car you are following so that you will have time to slow down. If road conditions are bad, you need to give yourself more room to slow down in case something happens.

If you're interested in calculating your braking distance using math formulas, check out our Distance Calculator.








Calculating Your Braking Distance: Learn Your Stopping Distance


Do a road test to check how long it takes you to stop.


While you might not think of your braking distance every time you drive across town, one day you will need to slow down as fast as possible. All sorts of things can go wrong, and highway driving is deceptively fast. Other drivers can drift into your lane, animals can wander in front of you—the potential for danger is very real. The following driving safety tips will help you understand what kind of braking distance you can expect from your vehicle and how speed affects how long it will take you to bring your car to a complete stop.

First, let's define a few terms:

  1. Braking Distance: Braking distance is the distance your car travels after the brakes have been applied. According to auto industry standards for deceleration, if you are traveling at 70 miles per hour, it takes 315 feet to stop an average car once the brakes have been applied.
  2. Stopping Distance: The term stopping distance takes into account the distance you travel before you hit the car brake system (reaction distance) plus the distance you travel while the brakes slow you down (braking distance). This might not seem like a big difference, but if you're moving down an interstate highway at 70 mph, you're passing 100 feet of asphalt every second.
  3. Reaction Distance: If it takes you 1.5 seconds at 70 mph to even realize that a problem exists, you've already traveled about 150 feet. That means you've passed half a football field before the brakes have even begun to kick in. Since half a football field is a long distance to cover before you even start slowing down, we include reaction distance in the discussion.
  4. Other Variables: Braking distance varies depending on many variables, including your reaction time, your speed, the weight of the car, road conditions, braking efficiency, and friction between the road surface and your tires. You can see that many things can go wrong when you need to brake in a hurry. That is why most traffic experts advise you to stay three to four seconds behind the car in front of you.

There are two times when you should be especially interested in calculating your braking distance:

Road Test: You can determine your braking distance on a test track or empty parking lot.

  • Make sure nobody is nearby—it's best to avoid having a real emergency braking situation.
  • Ensure that the area is empty before you start your road test.
  • Set up cones or use a landmark to indicate the point at which you will begin braking.
  • Bring a measuring tape or similar device to measure 10-foot intervals.
  • When you're ready, test your braking distance at 10, 20, 30, and 40 miles per hour. For safety's sake, don't test your braking distance at higher speeds, and keep the car going straight until you are stopped.

While Driving: Since you probably aren't interested in calculating all of those numbers while you drive, you might prefer to recall the three-second rule. Stay at least three seconds behind any car you are following so that you will have time to slow down. If road conditions are bad, you need to give yourself more room to slow down in case something happens.

If you're interested in calculating your braking distance using math formulas, check out our Distance Calculator.

Calculating Your Braking Distance: Learn Your Stopping Distance

Do a road test to check how long it takes you to stop.
Calculating Your Braking Distance: Learn Your Stopping Distance
Calculating Your Braking Distance: Learn Your Stopping Distance
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