Eye care at the Mac

The 20-20-20 rule on a Mac: how to actually stick to it

By the Mochi Genie team · Updated 19 October 2026 · Not medical advice

The rule

Every 20 minutes, look at something about 20 feet (6 metres) away for 20 seconds. The American Optometric Association recommends it to ease digital eye strain, along with a 15-minute rest after two hours of continuous screen time.

Why screens tire your eyes

When you focus on something close for a long time, the muscles that focus your eyes stay working. You also blink less: the American Academy of Ophthalmology says people normally blink about 15 times a minute, but only 5 to 7 times a minute while looking at a screen. Fewer blinks means drier, grittier eyes by the afternoon.

The good news, according to the same Academy: screens don't permanently damage your eyes. The discomfort is real, but it goes away with rest. That's what the 20-20-20 break is for.

Why it's hard to stick to

Nobody doubts the rule. The trouble is remembering it 24 times in an 8-hour day, and the reminders people try get in the way:

A phone timer goes off in the middle of a call and has no idea you just walked away for coffee.
Strict full-screen breaks work, but block your screen at the worst moment, so many people turn them off.
Plain notifications pile up in Notification Center and get swiped away without a glance.

The reminder that works is the one you keep switched on: one that waits for your meetings and is pleasant enough that you don't resent it.

Mac settings that make breaks easier

Match the brightness to the room. A screen much brighter than its surroundings makes your eyes work harder. On Macs with a light sensor, turn on System Settings ▸ Displays ▸ "Automatically adjust brightness".
Make text bigger instead of leaning in. System Settings ▸ Displays lets you pick a "Larger Text" resolution, and most apps zoom with ⌘ and +.
Sit back. The AOA suggests 16 to 30 inches from the screen, with the top of the display slightly below eye level. The AAO suggests about 25 inches, roughly an arm's length.
Cut glare. Angle the screen away from windows and bright overhead lights, and keep it clean.
Blink on purpose. When your break reminder comes, a few slow, full blinks help as much as the distant look.

Ways to get a 20-minute reminder on your Mac

Free

Our free 20-20-20 timer runs in your browser tab: press Start and it tells you when to look away and counts the 20 seconds. Nothing to install.
Stretchly (open source) shows a short "Mini break" on a timer you can set to 20 minutes and 20 seconds. It pauses while you're idle. It's only ad-hoc signed, so you approve it once in System Settings ▸ Privacy & Security.
Time Out has quick "Micro" breaks you can set to any interval, and rules that can skip breaks during calendar events or fullscreen apps.
A repeating timer on your phone or watch works anywhere, but can't tell when you're in a meeting or already away.

Our comparison of break reminder apps for Mac covers these and more in detail.

Paid

LookAway (from $19 one-time) is built around screen breaks, blink reminders and posture, and pauses automatically during meetings, video and games. If eye strain is your main problem and you want a strict, polished tool, it's a strong choice.
Mochi Genie ($12.99 once) is gentler. Its eye-rest reminder comes every 20 minutes by default: Mochi, the little genie on your desktop, closes its eyes, which is your cue to look out of the window. Mochi waits while your microphone or camera is on or you're in a fullscreen app, and treats 5 minutes of idle time as a break you already took. It also reminds you about water, stretching and posture.

Mochi resting its eyes — Mochi's eye break: when Mochi closes its eyes, you look at something far away. Tap "Done" when you're back. (Mochi doesn't count the 20 seconds or dim your screen; it's a nudge, not a lock.)

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Questions

Does it have to be exactly 20 feet?

No. The point is to relax your focus on something far away. Looking out of a window or across the room is perfect.

Is 20 seconds enough?

It's the minimum the rule suggests. Longer is fine, and the AOA also recommends a longer 15-minute rest after two hours at the screen.

Do I need to do it in meetings?

Glancing away for a few seconds during a long call is easy and nobody notices. But a reminder that pops up on a shared screen is embarrassing, which is why it's worth using an app that waits until the call ends.

When should I see a doctor?

If eye strain doesn't ease with breaks, or you notice blurred or double vision, headaches or pain, see an optometrist or ophthalmologist. This page is general information, not medical advice.

Sources

American Optometric Association: computer vision syndrome (the 20-20-20 rule, screen distance and position, the 15-minute rest)
American Academy of Ophthalmology: computers, digital devices and eye strain (blink rate, distance, brightness, no permanent damage)
Stretchly, Time Out, LookAway pricing