Screen time calculator.

How it is worked out

Hours a week is daily hours × 7, hours a year is daily hours × 365, and a month is a year divided by 12. Your share of waking hours is daily screen hours ÷ (24 − sleep hours). Time until your chosen age is that share times the years between your age and the age you pick. The cut-back line multiplies the hours you cut by 365.

Worked example. 6 hours a day with 8 hours of sleep. 6 × 7 = 42 hours a week and 6 × 365 = 2,190 hours a year, which is 91.3 full days. Waking hours are 16, so 6 ÷ 16 = 37.5%. Cutting 2 hours a day saves 730 hours a year.

Eye comfort

The American Academy of Ophthalmology says people normally blink about 15 times a minute but only about 5 to 7 times a minute on a computer, and advises looking up from the screen to something distant now and then. Source (opened 2026-10-05): AAO, Eye Strain and Digital Devices, published June 27, 2024. The tool does not judge whether your screen time is too high, since that depends on what you use screens for.

FAQ

How many hours a year is 5 hours a day on a screen?

5 hours × 365 = 1,825 hours, which is about 76 full days.

What share of my waking life is that?

Divide your daily screen hours by your waking hours. With 8 hours of sleep you wake for 16 hours, so 4 hours of screens is 25%.

Where do I find my screen time?

iPhone has Screen Time in Settings, Android has Digital Wellbeing, and Windows and Mac show app usage in their settings. Average a few days.

Is there a safe amount of screen time?

This tool does not set a limit. The American Academy of Ophthalmology advice is about eye comfort: blink often and take breaks to look at something far away.

Why project to an age?

It turns today’s habit into a long-run total. You pick the age, so it is a what-if, not a prediction of how long you will live.

Fit in movement: steps to miles.