The Screen Time Cost Calculator

The assumptions, out in the open

A waking day is counted as 16 hours (assuming roughly 8 hours of sleep). The lifetime projection runs to age 80 and assumes your current daily average stays constant — real life won't be that neat, but it's the honest way to show what a habit costs if nothing changes. A book is counted as 8 hours of reading (a typical novel at an average reading speed). The language estimate uses roughly 700 hours of study, in line with the U.S. Foreign Service Institute's published estimates for reaching professional working proficiency in languages closely related to English, such as Spanish or French.

One thing this calculator deliberately doesn't claim: that all screen time is wasted. Some of your hours are work, connection, and things you'd choose again. The number worth staring at is the share that just happened to you — the reflexive, unchosen part. If you want to know where your time actually goes, your phone's built-in screen time report will tell you; if you want to change the reflexive part, that's what reducing screen time at the root is about.

Where your number comes from

If you're not sure what to enter, check your phone: Settings → Screen Time on iOS, or Digital Wellbeing on Android. Most people underestimate their real number substantially. For context on how your country compares, see our screen time by country reference — global averages run well over 6 hours per day of total screen time.