Fatigue Fuel Recovery Calculator

The Hidden Fuel Cost of Driver Fatigue

Most fleets treat fatigue as a safety problem, and it is. But fatigue also shows up somewhere less obvious: the fuel line of your P&L. A tired driver's reaction time slows, following distances shrink and speed control slips, which leads to more late, hard braking and more hard acceleration to get back up to speed.

Your telematics platform already counts those harsh events. This calculator turns that count into gallons and dollars, so you can put a number on what fatigue costs your fleet beyond the incident reports.

How harsh driving events burn fuel

When a loaded truck brakes hard, the momentum it took fuel to build is turned into heat in the brakes. Getting that truck back to speed means burning the fuel again. One event is small, but across a fleet running hundreds of miles a day, five days a week, the waste adds up to thousands of gallons a year.

Not every harsh event is caused by fatigue. That's why the calculator asks you to set the share of events you believe are fatigue-linked, and how much of that waste a fatigue program could realistically remove. You stay in control of every assumption.

Fatigue Fuel Recovery Calculator: Frequently Asked Questions

Where do I find my harsh event numbers?

Telematics platforms such as Samsara, Motive and Geotab track harsh braking and harsh acceleration as standard. Look for a safety or driver behavior report and pull the combined count for a recent period.

Some platforms report events per vehicle per day and others per 1,000 miles. The calculator accepts either, so you can enter the figure exactly as your report shows it.

How much fuel does one harsh event waste?

It depends on the vehicle, its load and how much speed is lost. Research from Oak Ridge National Laboratory and the Virginia Tech Transportation Institute puts a full stop-and-restart cycle for a Class 8 truck at roughly 0.25 to 0.50 gallons.

Many harsh events slow a truck without stopping it, and pickups and light-duty vehicles lose less per event than a loaded tractor-trailer. If your fleet is mixed or mostly light-duty, set the slider toward the lower end.

A lower setting gives a more conservative estimate, which is usually the stronger position when you take the number to finance or leadership.

What share of harsh events is linked to fatigue?

The best answer comes from your own data. If you can compare harsh event rates on late, long or back-to-back shifts against well-rested shifts, the difference gives you a defensible fatigue share.

If you don't have that comparison yet, pick a share you'd be comfortable defending and test a few values to see how sensitive the result is. Once drivers are completing fitness-for-duty checks, you can measure the link directly.

Which efficiency gain range should I pick?

The three ranges reflect how much of the fatigue-linked waste you expect a fatigue program to remove. Cautious (5 to 15%) suits a first business case or a skeptical audience. Moderate (15 to 30%) suits a program with clear follow-up when a driver is flagged. Confident (30 to 45%) suits fleets that already act consistently on fatigue data.

The results panel shows savings at the low, chosen and high points of your range next to the investment, so you can see whether the program pays back even at the bottom of the range.

Should I include incident avoidance?

Fuel is the most conservative way to build the case, because it rests on numbers you already track. Incident avoidance is optional, but fatigue-related incidents are often the larger cost once you count claims, repairs, downtime and admin time.

If you switch it on, enter the number of fatigue-related incidents you see in a typical year and your average cost per incident. The calculator applies the same reduction you chose for harsh events.

How does SafetyIQ help reduce fatigue-linked driving?

SafetyIQ's fatigue management gives drivers a quick, two-minute fitness-for-duty test before they start a shift. Results are checked against thresholds you set, and supervisors are alerted when a driver needs attention before they get behind the wheel.

A daily dashboard shows trends across your crews, so you can spot the shifts, routes and rosters where fatigue builds up and fix the cause, not just the symptom. Fewer fatigued drivers on the road means fewer harsh events, less fuel waste and fewer incidents.