There’s a reason the saying, “Time is money” has stood the test of time. It’s because the saying is true, more than you know. When salaried workers work extra hours, they’re getting a pay reduction. And if you change jobs and work more hours, a pay increase might not make up for the extra time. There are times when you need to work extra hours, but if it becomes a habit, make sure you realize the effect on your pay.

I was curious to see the numbers, so I wrote an hourly wage calculator and was stunned by the results.

If you make $50K and work 55 hours a week instead of 40, it reduces your hourly wage from $24.04 to $17.48, or $36K a year. From another perspective, if you make $50K working 40 hours a week and you’re considering a new job that requires 55 hours a week, you’d need to make $69K to earn the same per hour.

Think about this next time you’re putting in extra time at the office.

Here are two sobering charts generated by the calculator.