Free 20-20-20 timer
for eye breaks

How this timer works

Start the timer and leave the tab open. When the 20 minutes are up, a soft chime plays, the page fades into a full-screen break card, and 20 seconds count down while you look at something far away. When the countdown ends, the card fades out and the next 20 minutes begin on their own. If a break lands mid-sentence, the Skip button ends it immediately.

• Accurate in a background tab. The countdown is computed from timestamps, not from tick counts, so switching tabs or windows does not slow it down.
• Optional notifications. Turn the toggle on and your browser asks for permission at that moment, never on page load. After that, each break also arrives as a system notification while the tab is hidden. Decline and the rest of the timer still works.
• A count of the breaks you took today. Stored in your browser's local storage, reset each day, never sent anywhere. Skipped breaks do not count.
• Keyboard and motion friendly. Space starts and pauses when the countdown has focus, Escape skips a break, and the ring animation is replaced by a plain fade if your system asks for reduced motion.

What the rule is, and what the evidence says

The 20-20-20 rule is a memory aid for screen breaks: every 20 minutes, look at something roughly 20 feet away for 20 seconds. An optometrist popularized it in the 1990s. The three twenties were chosen because they are easy to remember, not because a trial found them optimal.

The evidence on those exact numbers is mixed. Some studies find that break reminders reduce eye strain and dry eye symptoms while people use them; others find no difference between intervals of 5, 10, 20, or 40 minutes. We wrote up the studies in detail rather than repeat them here: does the 20-20-20 rule actually work. The short version is that stopping a long stretch of near work to look at something distant is a reasonable habit worth keeping, and the specific numbers are a starting point you can adjust rather than a prescription.

If you want this without a browser tab open

This page only runs while its tab is open, which is fine for a work session and useless the moment you close the browser. Nox does the same thing as a native macOS notification, from the menu bar, at any interval from 10 to 60 minutes, with a guided 20 second countdown when the break starts. It is the same app that filters your screen with spectral presets built on melanopic suppression research, so the reminder and the display settings live in one place. Nox is $5 once, with a 14-day free trial, and requires macOS 14 or later.

Frequently asked questions

What is the 20-20-20 rule?

Every 20 minutes of screen work, look at something about 20 feet away for 20 seconds. An optometrist popularized it in the 1990s as a habit that is easy to remember. The numbers were picked to be memorable, not tuned by a clinical trial.

Does the timer keep running if I switch tabs?

Yes. The countdown is calculated from timestamps rather than counted ticks, so it stays accurate while the tab sits in the background and shows the right time the moment you come back. Browsers slow down background tabs, so a break can arrive a few seconds late. If you close the tab or quit the browser, the timer stops.

Do I have to allow notifications?

No. The timer works without them, using the on-page break overlay and a soft chime. Turning the toggle on asks your browser for permission, and after that each break also arrives as a system notification while the tab is hidden. If you decline, the toggle switches back off and everything else keeps working.

How do I get eye break reminders without keeping a tab open?

This page only runs while its tab is open. Nox is a macOS menu bar app that fires the same reminder as a native notification at an interval you choose, from 10 to 60 minutes, whether or not a browser is running. It is $5 once, with a 14-day free trial, and requires macOS 14 or later.