Eye Strain 20-20-20 Rule Timer/Calculator
Enter your daily screen time and break frequency to calculate 20-20-20 compliance and eye strain risk.
Total hours per day looking at screens (work + phone + TV)
How often you want reminders to look away
Longest uninterrupted work session (e.g., morning block)
What is the 20-20-20 rule for eye strain?
The 20-20-20 rule states: Every 20 minutes, look at something 20 feet away, for at least 20 seconds. This relaxes the ciliary muscles that focus your eyes and reduces digital eye strain. Studies show it can reduce eye fatigue by 40-50% in office workers. Set a timer or use apps like "Stretchly" or "Eye Care 20 20 20" to build the habit.
How much screen time causes eye strain?
Symptoms typically start after 2-3 hours of continuous screen use. Risk factors: Over 6 hours/day (high risk), 4-6 hours (moderate), under 3 hours (low). Other factors: Screen brightness vs room lighting mismatch, blue light exposure after sunset, poor viewing distance (should be 20-28 inches), and not blinking enough (reduces from 15x/min to 5x/min when staring at screens).
What are symptoms of digital eye strain?
Common symptoms: Dry/irritated eyes, blurred vision, headaches (especially frontal), neck/shoulder pain, light sensitivity, difficulty focusing, watery eyes, burning sensation. If untreated, can lead to computer vision syndrome (CVS) with chronic dry eye, reduced productivity, and sleep disruption from blue light. Children are especially vulnerable - limit to 1-2 hours/day.
Does blue light filter help with eye strain?
Blue light filters (Night Mode, f.lux, blue light glasses) help primarily with sleep quality, not eye strain directly. For strain relief: 1) Follow 20-20-20 rule, 2) Increase blinking (conscious effort), 3) Adjust screen brightness to match room, 4) Use artificial tears (preservative-free), 5) Position screen 20-28" away, 6-8" below eye level. Blue blockers help evening screen use by preserving melatonin.