Where Is Your Blind Spot?

weirdly accurate.

Where Is Your Blind Spot?

    Where is my blind spot?

    About 15 degrees out from where you are looking, on the side away from your nose, slightly below eye level, and roughly 5 degrees across. In Ehinger and colleagues’ 2017 eye-tracking study of 100 people, its centre sat 15.5° out in the left eye and 15.9° in the right. Every healthy eye has one: it is where the optic nerve leaves the retina, and there are no light-sensitive cells there.

    This test maps yours with a bank card and a moving dot. First the card sets the scale: you resize an outline until it matches a real card, 85.60 mm wide, so the test knows how big a millimetre is on your screen. Then you set your distance on a tape measure, or let your blind spot work it out with the “virtual chinrest” rule of Li and colleagues (2020). With one eye shut and the other on a cross, a pink dot travels at 2° per second, and you tap when it vanishes and again when it comes back. Four passes per eye (outward, inward, down, up) give where the spot starts, its centre, width and height; each edge is averaged over two opposite passes to cancel the delay of your tap. Your numbers are set beside three published samples: 30 lab participants for where the spot starts (Li et al.), 100 eye-tracked people for width and the left–right difference (Ehinger et al.), and 11,449 clinic visual fields for how far below eye level it sits (Wang et al.).

    This is not an eye test. Everyone has this blind spot, and a screen at home cannot measure your field of vision the way an eye clinic’s perimeter does; nothing here can show or rule out an eye condition. If you notice a new blank, dark or blurry patch in your vision, one you see without looking for it, get it checked by an eye doctor promptly. The numbers also depend on the distance you entered and on keeping your head still: 2 cm off at 50 cm shifts every angle by about 4%.

    What the test measures

    One thing, mapped for each eye: where the patch you can’t see sits, and how big it is.

    The task

    • Calibrate with a bank card or any card that size (ISO/IEC 7810 ID-1, 85.60 × 53.98 mm): resize the outline until it matches
    • Set your eye-to-screen distance on a tape measure, or let the blind spot work it out (the virtual chinrest of Li et al., 2020)
    • One eye at a time: keep your eye on a cross while a pink dot moves at 2° per second; tap when it vanishes and when it returns
    • Four passes per eye, outward, inward, down and up; a pass that doesn’t add up gets a retry

    Your result

    • Where each blind spot sits, in degrees from the centre of your vision, and how wide and tall it is; in can’t-measure mode, how far you sit from the screen instead
    • Where your spot starts against Li et al.’s 30 lab participants (13.6° on average, 11.5°–16.0°), or your distance against their 1,153 online participants (17–68 cm, 47 cm on average)
    • Width and the right-versus-left difference against Ehinger et al.’s 100 eye-tracked participants; the vertical position against 11,449 clinic visual fields (Wang et al., 2017)
    • A map of both visual fields, three filling-in tricks drawn on your own blind spot, and everyday terms such as how far away a bank card would vanish inside it
    • A share card and a challenge link that carries your number in the part after the #; no account

    Before you start

    • A bank card or any card that size: ID card, driving licence, transit card
    • A phone held sideways or a computer: the dot needs room to travel; WebGL (3D) switched on
    • A tape measure helps; on a phone, about 30 cm from your eyes works well
    • About three minutes, keeping your head still while the dot moves

    Blind spot FAQ

    Is this test free? Do I need to sign up to see my result?

    Yes, it’s free, and there’s nothing to sign up for: no account, no email, no payment. Your result appears on this page the moment you finish, and you can share it or play again straight away.

    How do I find my blind spot?

    Shut one eye, look at a fixed point and move a small dot outward from it: about 15° to the side, away from your nose, the dot disappears. The French physicist Edme Mariotte did it in the 1660s with two white spots on a dark background, backing away until the second vanished at about nine feet. This test does the same with a moving dot and measures where your blind spot starts and ends.

    Is it normal to have a blind spot in your eye?

    Yes. Every healthy eye has one, where the optic nerve leaves the retina and there are no light-sensitive cells. You don’t notice it because your two eyes cover for each other, your eyes keep moving, and the brain fills the gap from its surroundings. A new blank, dark or blurry patch that you notice without looking for it is different: get it checked by an eye doctor promptly.

    How big is the blind spot in the eye?

    About 5° across. In Ehinger and colleagues’ 2017 study of 100 eye-tracked people it measured 4.82° in the left eye and 4.93° in the right, centred 15.5° and 15.9° out from where they looked. In 11,449 clinic visual fields its centre sat 2.1° below the line of sight (Wang et al., 2017). A moving dot like the one in this test makes the spot read a little narrower.

    Can a blind spot test detect glaucoma or other eye problems?

    Not this one. A screen at home cannot measure your field of vision the way an eye clinic’s perimeter does, and nothing in this test can show or rule out an eye condition; it shows a normal feature of every eye. If you notice a new blank, dark or blurry patch in your vision, or have any worry about your sight, see an eye doctor.

    How can my blind spot tell how far I sit from the screen?

    Because it sits in nearly the same place for everyone. In Li and colleagues’ 2020 “virtual chinrest” study, the point where a dot first vanished averaged 13.59° across 30 people, with a standard deviation of 0.96°. Finding where the dot vanishes on screen therefore gives your distance; in their lab check the average error was 3.25 cm. This test’s can’t-measure mode uses the same rule.

    Why are my left and right blind spots in different places?

    A small difference is normal. In Ehinger and colleagues’ 2017 study, the right eye’s blind spot sat on average 0.36° further out than the left. In a test at home, moving your head during the passes and a distance that is slightly off also shift the numbers, so the left–right difference from a single run is rough.

    How long does the blind spot test take, and what do I need?

    About three minutes. You need a bank card or any card the same size, and a phone held sideways or a computer; a tape measure helps but isn’t required. Each eye gets four passes of the dot, and you keep your head still while it moves. It is free and needs no account.

    Where the numbers come from

    Percentiles treat the published averages and spreads as a normal distribution, because the papers give no per-person data. Li et al. measured where the spot starts in 30 people in a lab and viewing distance in 1,153 people online; Ehinger et al. eye-tracked 100 people; Wang et al. analysed 11,449 visual fields from glaucoma-clinic patients whose fields were unaffected. The site does not publish its own players’ data.

    How the map is measured

    Card calibration

    A real card’s width (85.60 mm) gives the number of screen pixels per millimetre, so every dot position can be turned into an angle from your distance.

    Two-way passes

    A tap always lands a moment after the dot crosses an edge. Averaging the same edge seen from opposite directions cancels that delay; the “starts at” figure uses the outward pass alone, as Li et al. did.

    Virtual chinrest

    If you can’t measure your distance, it is worked out as where the dot vanished divided by tan 13.5°, the rule from Li et al. (2020). Every other angle then follows from that distance.

    Percentiles

    The published averages and spreads are treated as a normal distribution, because the papers give no per-person data; the percentiles are approximate.