# How to Calculate Engine Hours

by Peter H. Crawford
Jupiterimages/Goodshoot/Getty Images

"Engine hours" refers to the number of hours that your engine has been running since it was new. Many construction vehicles, trucks or other vehicles that spend a lot of time idling have a meter that tracks engine hours, which can give their operators a better handle on engine maintenance. Unfortunately, if your vehicle does not have an engine hour meter, there is no way to calculate its exact number of engine hours; however, if you know your average commute time and distance, there is an equation that can help you approximate your engine hours.

## Step 1

Begin a typical week by resetting your trip meter to zero. Keep a stopwatch (one that will keep time for at least 20 to 50 hours) in your vehicle with you. Start the stopwatch each time you start your car, and stop it when you turn the engine off.

## Step 2

After a week has passed, write down the total mileage from your trip meter and the total time from the stopwatch. Convert all minutes to hours for your time unit by dividing them by 60.

Example: (30/60 = 0.5) 30 minutes = 0.5 miles; (15/60 = 0.25) 15 minutes = 0.25 miles; etc.

## Step 3

Divide the mileage by the hours to determine your average travel speed for the week.

Example: 375 miles driven in a week/18.5 hours = 20.27 average mph for the week

## Step 4

Divide your vehicle's total mileage displayed on the odometer by your average mph for the week to determine an estimate of your engine hours.

Example: 22,550 total miles/20.27 average mph = 1,112.48 engine hours