What is the 20-20-20 Rule?
The 20-20-20 rule (also known as 20/20/20 rule, blink break rule) is a guideline created by American optometrist Dr. Jeffrey Anshel in 1991 to help reduce digital eye strain (also called computer vision syndrome). The rule states for every 20 minutes of screen time, look at something at least 20 feet away (6.096 meters), for at least 20 seconds. By taking periodic breaks from looking at your screen and looking at somthing far away, you allow your eyes to relax, reducing eye strain.
While not commonly mentioned, Dr. Anshel also suggested that people follow the 3-B approach: blink, breathe, and break:
Blink: People tend to blink less often when staring at digital screens, which contributes to dryness and irritation. Anshel’s approach reminds people to consciously blink more often.
Breathe: Because extended screen work can cause tension, stress, and shallow breathing, Anshel encouraged deeper breathing to help relieve general (non‐ocular) tension. He believed breathing was important in reducing stress.
Break: The “break” part is where the 20-20-20 prescription comes in. Every 20 minutes, look at something ~20 feet away for ~20 seconds to let the eye muscles relax.
You can do more to help your eyes and body while working (read more about Better alternatives and improvements to the 20-20-20 rule).
The 20-20-20 Rule Timer
The timer on this website is to help people follow the 20-20-20 rule created by Dr. Jeffrey Anshel to reduce eye strain and computer vision syndrome. Start the timer and for 20 minutes, spend time working. Once the timer goes off, click start again and spend the 20 seconds relaxing your eyes by looking 20 feet away (6.096 meters).
You can change the work and rest duration in settings, along with many other configurations. Such as the additional seconds to add, the alarm tone, mute sounds, notifications, and voice announcements, these configurations will be saved. [Read the full settings guide]
How to use the buttons
- Start: Begins the timer. It starts with the work phase; after a work session finishes, pressing Start again begins the rest phase.
- Pause: Pauses the countdown. Press Start again to resume the timer.
- Reset: Stops the timer and restarts it from the beginning of the work phase.
- Mute: Appears only when the alarm is sounding. Silences that alarm without affecting future timers. To mute alarms and sounds go to settings.
- Skip to rest: Will end/skip the work timer and start the rest phase.
- Skip to work: Will end/skip the rest timer and start the work phase.
- Add +60 sec: Extends the current countdown by 60 seconds (the amount of added time can be customised in settings).
What is eye strain?
Asthenopia (more commonly known as eye strain or eye fatigue) is when your eyes feel tired, uncomfortable, or sore after extended use. Usually it’s not serious, but it can be bothersome and affect your daily activities. It often occurs when you visually focus on tasks for a long period, especially close-up work.
Causes of eye strain
- Looking at digital screens (computers, phones, tablets) without regular breaks
- Reading or writing for long periods
- Working in poor or overly bright lighting
- Looking at surfaces with glare for prolonged periods
- Incorrect eyeglass prescription
- Dry eyes (reduced blinking while focusing)
- Driving long distance
- Bad posture causing you to move closer to your screen
Common symptoms of Asthenopia / eye strain / eye fatigue:
- Tired, burning, or itchy eyes
- Blurred or double vision
- Headaches (often around the eyes or forehead)
- Increased sensitivity to light
- Neck, shoulder, or back discomfort (from posture while straining to see)
The physiology behind eye strain
When you focus on something up close, like a book, phone, or computer, tiny muscles inside your eye (the ciliary muscles) contract to change the shape of your eye lens, allowing you to focus clearly. At the same time, your extraocular muscles (the ones that move your eyes) must keep both eyes aligned on the same point, a process called vergence.
If you keep this focus on close up objects for long periods without breaks, those muscles can become fatigued, just like your leg muscles would if you held a squat too long. This is the root of asthenopia: your eyes’ focusing and alignment systems are overworked.
What is computer vision syndrome?
Sometimes also called digital eye strain, computer vision syndrome (CVS) is a more specific condition, where eye strain is caused by prolonged digital screen use. Includes the common eye strain symptoms (tired, sore eyes, blurred vision, headaches) plus factors unique to screens: Reduced blinking, thus leading to dry eyes, and poor posture while using devices. CVS is a type of eye strain.
Computer vision syndrome has become increasingly common as people around the world spend more time on digital screens for both work and leisure. Many jobs now require extensive screen use, and in their free time, people often turn to screens for gaming, streaming films and media, or reading books and articles. We are surrounded by the use of screens in our faces, staring our eyes - but we can mitigate this.
How to mitigate asthenopia (eye strain) and computer vision syndrome
The best way to reduce eye strain and computer vision syndrome is to give your eyes rest, improve your visual environment, and support good eye health.
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Follow the 20-20-20 rule
Every 20 minutes, look at something 20 feet away for at least 20 seconds.
This relaxes the eye muscles that focus up close. -
Adjust screen setup
Keep the screen 20–28 inches (50–70 cm) from your eyes.
The top of the screen should be at or slightly below eye level.
Reduce glare by using a matte screen filter or adjusting lighting. -
Optimise lighting
Avoid harsh overhead lights or strong glare from windows.
Use soft, indirect lighting.
Adjust brightness and contrast on screens so they’re comfortable (not too dim or too bright). -
Blink more often
Screen use lowers blink rate, therefore leading to dry, irritated eyes.
Remind yourself to blink or try the 20-20-20 rule as a cue.
Artificial tears (lubricating eye drops) can help if dryness persists. -
Use proper corrective lenses
Make sure your glasses or contact prescription is up to date.
Consider computer glasses (anti-reflective coating, blue-light filter, or intermediate-distance correction if needed). -
Ergonomics & posture
Sit with good posture; screen at arm’s length.
Take short breaks to stand, stretch, and roll your shoulders.
Here's some useful YouTube videos on ergonomics & posture: -
Manage screen time
Alternate between screen and non-screen tasks when possible.
For children, balance digital learning/entertainment with outdoor activities.
Criticisms of Dr. Jeffrey Anshel’s 20-20-20 rule
The 20-20-20 rule created by Dr. Jeffrey Anshel in 1991 aimed to help reduce eye strain for prolonged computer users who often reported having eye issues. Based on recent studies and commentary Dr. Anshel’s guidance faces some criticism and limitations. While the general consensus still agrees, taking periodic breaks from computer screens and focusing on further distances to relax your eyes is very important to preventing eye strain. The duration of working and resting periods is often criticised, along with the lack of suggestion of movement, limited empirical evidence for helping reduce eye strain for everyone, question of effectiveness and arbitrary numbers.
Critics argue that 20 seconds might be insufficient for many users to truly rest the eyes, especially when staring continuously at screens for prolonged periods. Some suggest longer breaks or breaks that involve movement, not just changing focus. Additionally, the ‘20 feet’ distance may not always be possible in many environments (small rooms, cramped offices) or meaningful (if there's nothing interesting/distant enough to focus on).
The 20-20-20 rule focuses solely on eye health and not just general health while working. While it is made to reduce eye strain, critics say that incorporating movement, posture and ergonomics would be much more useful than just looking 20 feet away, for 20 seconds. Having your workstation set-up in a correct manner would both benefit your eyes and more importantly, your whole body (Read more about ergonomics & posture in 6. Ergonomics & posture along with useful YouTube videos).
Another issue is with discipline to the rule, many people forget to take breaks, ignore them or just glance at somthing for a couple of seconds not following the full ‘20 feet away, for 20 seconds’ rule. In the study “The effects of breaks on digital eye strain …,” improvements in self-reported dry eye symptoms and digital eye strain were seen with the 20-20-20 reminders over two weeks. But after stopping the reminders, the improvements tended to fade. This suggests that consistency / habit-building is required, and that short-term adherence may not lead to lasting change without ongoing effort.
Better alternatives and improvements to the 20-20-20 rule
The main criticism of the 20-20-20 rule is that taking regular breaks and looking far away isn’t enough to improve eye strain, and that the rule focuses solely on eye health and not general body strain while working. Critics say that better guidance would be to have physical movements: stand, stretch, roll your shoulders, short walk etc while you take your break. Allowing you to relax and stretch more muscles of your body, improves blood flow, and relieves stress.
Another improvement is setting up your workstation in the correct manner, this would both benefit your eyes and more importantly, your whole body. This can reduce neck pain, shoulder tension, back pain, etc (Read more about ergonomics & posture in 6. Ergonomics & posture)
Some studies suggest taking longer breaks every 60-90 minutes with 5 - 10 minutes breaks can help. This gives both the eyes and body more rest while still giving time to be concentrated on your work. Other studies on break schedules suggest that “self-paced breaks” or more frequent, individualised breaks yield better results than rigid schedules. You can change the work / rest duration in the timer settings to match your schedule.
The best break/work schedule for you depends on what’s most important to you. If you want to maximise physical health, try taking longer breaks with more movement, breathing and reflections on your posture. If you want to maximise concentration and work, try doing longer work phases and regular but small breaks. Still relaxing your eyes and moving your body.
Our suggestions for break and rest schedules
You can change the time durations in settings to fit what works best for you, or you can try one of our guides by clicking on "try now".
Health, posture and eye strain
Every 20 minutes working, take a 3 minute break, reflect on ur posture: see if you’ve started slouching subconsciously or out of the optimal posture (if you keep going back to a bad posture you may need to adjust your ergonomics), look 20 feet away, stand up, stretch, try and move around, roll your shoulders and take deep breaths.
Work, productivity and concentration
Every 45 minutes working, take a 5 minute break. In the first 2 minutes, roll your shoulders, stretch your arms in the air whilst reflecting on the work you have done, spend the next 2 minutes standing up, moving around and letting your mind wander slightly and relaxing. In the last 1 minute, reflect on what you need to do and slowly go back to working mode.
Studying, revision and learning
Every 30 minutes working, take a 6 minute break. Spend the first 2 minutes mentally reviewing what you learned or re-learned (try a quick mind-map, eyes closed if helpful). Use the next minute to roll your shoulders, stretch and breathe while noting progress and what you'll do next. In the last 3 minutes walk around, relax and stretch. Avoid phone use during work, and for better discipline, avoid it during breaks too.
Deep concentrated work
Every 60 minutes working, take a 5 minute break. In the first 2 minutes, roll your shoulders, stretch your arms in the air whilst reflecting on the work you have done, spend the next 2 minutes standing up, moving around and physically relaxing but thinking of work. In the last 1 minute, reflect on what you need to do and go back to working.
Eye care
Every 15 minutes working, take a 2 minute break. Use the first to notice how your eyes feel, how dry or tired they are, blink a few times to re-lubricate them. reflect on your posture, see if you need to adjust it. Bad posture can lead to more eye strain. Use the next minute to look at something 20 feet away, try and focus on different objects at different distances. This helps relax your eye muscles. Remember to blink often while working.
Mental wellbeing and health
Every 20 minutes working, take a 5 minute break. Use the first minute to check posture and look about 20 feet away. For the remaining time close your eyes, take slow deep breaths and focus on how your body and breath feel; if your mind wanders, gently bring attention back to the breath. When the break ends, open your eyes slowly and return to work.
These are just suggestions, what works for you depends on your own needs. You can use these as inspiration and set your own times and things to do during your break. Click on settings to input your own time durations.