Americans tend to overestimate how many hours they work in a typical week by about 5 to 10 percent, according to study published in a Labor Department journal, with the biggest exaggerators being people who work longer weeks.

The study compared people’s estimates for how much time they spent working against a time diary they were asked to keep of all their activities. …

The typical person who reported having worked 40 hours, for example, actually worked closer to 37. The report found that “The greater the estimate, the greater the overestimate”; people who said they worked 75 hours actually worked closer to 50 hours. (That’s an overestimate of 25 hours, or 50 percent!) At the other end of the spectrum, people who worked relatively few hours (under around 25) actually ended to underestimate their hours.