Screen Eye Strain Calculator
Calculate your eye strain risk based on screen time, distance, breaks, and lighting conditions.
Computer Vision Syndrome (also called Digital Eye Strain) affects an estimated 50–90% of people who work at computer screens. Symptoms include eye fatigue, dryness, blurred vision, headaches, and neck pain.
Key risk factors:
Screen distance: The ideal distance is 20–26 inches (50–65 cm) from your eyes. Screens closer than 16 inches (40 cm) force your eye muscles to work significantly harder to maintain focus. Every inch closer increases strain exponentially.
Screen time duration: Risk increases dramatically after 2 continuous hours. The average office worker spends 6–8 hours looking at screens daily. Adding phone and TV use, many people exceed 10 hours total.
The 20-20-20 Rule: Every 20 minutes, look at something 20 feet (6 meters) away for at least 20 seconds. This relaxes the ciliary muscles that control focus. Studies show this simple practice reduces eye strain symptoms by 30–40%.
Blink rate: Normal blink rate is 15–20 times per minute. When staring at screens, blink rate drops to 5–7 times per minute, causing dry eyes. Consciously blinking more often helps, as does using artificial tears.
Lighting: Glare from overhead lights or windows reflecting off your screen is a major contributor. Your screen brightness should match the ambient light level — not brighter, not dimmer. A too-bright screen in a dark room is particularly harmful.
Blue light: Blue light (400–490 nm wavelength) from screens can disrupt sleep patterns when viewed in the evening. While blue light blocking glasses are popular, research on whether they reduce eye strain during daytime use is inconclusive. The bigger factor is overall screen habits.
Tip: Position your screen so the top of the display is at or slightly below eye level. Looking slightly downward reduces the exposed surface area of your eye, which slows tear evaporation.