5413058107_2db1a4c43d_bphoto: Yoshitomo Oda via Flickr

If you think you’ve lost a lot of sleep since your little bundle of energy came into the world, you’re probably right. But about how many zzzs are you losing out on? This fun calculator will tell you!

The Lost Sleep Calculator for Parents was designed by Hillarys, a UK interior design company (we guess they’re trying to sell you on blinds, curtains and other furnishings to up your sleep intake). All you have to do is enter how many kids you have and how old they are, and the calculator will calculate exactly how many hours of sleep your kids have stolen with all those early morning wake-ups, sleep training mishaps and middle-of-the-night cuddle sessions.

For example, three children, ages 2, 5 and 7, have already taken a whopping 9,990 hours of sleep from their parents. That’s 416 days!

We can’t vouch for the accuracy of the calculator. It is designed by a design company, after all, not a medical university. But still, it’s a fun way to make yourself feel validated when you’re feeling too exhausted to read one… more… bedtime… story.

How many hours of sleep have you lost? Tell us in the comments below.