Time Saved by Speeding Calculator

See how much time two driving speeds differ in perfect conditions, then account for the parts of a real route where neither speed can be maintained.

Your inputs stay in your browser. Calculations happen locally and nothing is uploaded.

Compare two speeds

Enter speeds you want to compare. The calculator does not determine whether either speed is legal or safe.

miles
mph
mph

Optional: separate the route into miles where the speed comparison applies, constrained roadway, and fixed delays. No generic traffic assumptions are added.

Real-world route conditions

Split the route first, then add delays. No generic traffic assumptions are added.

Split the route

Only the open-road portion can produce a difference between the two selected speeds.

miles
mph

The selected speeds apply to 20 of 30 miles. The remaining 10 miles use the shared slower speed.

Add fixed delays

These delays are added equally to both trips.

What these change: total trip times and the percentage saved. They do not change the seconds saved because the same delay occurs in both scenarios.
Traffic signals
sec
Stop signs
sec
minutes
minutes

Estimated real-world difference

Trip at normal speed
Trip at comparison speed

Route breakdown

Open-road portion (normal vs. comparison)
Constrained-road travel
Traffic signal delay
Stop-sign delay
Congestion delay
Other delay
All fixed delays
Estimated travel-time reduction

Theoretical maximum

Normal-speed travel time
Comparison travel time
Maximum time difference
Travel-time reduction

Assumes the selected speed can be maintained continuously for the entire distance, with no slowing, stops, or delays.

Frequently Asked Questions

The theoretical difference is the trip distance divided by each speed. Actual savings are usually smaller when only part of the route allows either speed or the trip includes lower-speed roads.

Seventy-five mph is about 15.4 percent faster than 65 mph, but uninterrupted travel time is reduced by about 13.3 percent. Over 30 miles, the theoretical difference is about 3 minutes 42 seconds.

A higher selected speed affects only the portions where it can be maintained. Lower-speed streets, queues, turns, signals, and stops limit that portion of the trip.

Signal delay adds time to both scenarios. It does not change the speed-related seconds saved unless the signal experience differs, but it makes those seconds a smaller share of the total trip.

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