How far should I stand from my phone for an eye test?

For a phone, 1m–2m is recommended. At 3m or more you would need someone to hold the screen or press your answers, and at 5m the large 0.1 ring will not fit on the screen. When you choose a distance, this tool shows the range it can measure, such as “This screen can measure 0.1 to 2.0,” so use that to choose. Computer screens can have coarse pixels, so standing 2m–3m away lets finer rows be drawn.

How does the size of a Landolt ring change with distance?

A 1.0 ring is sized so that its gap subtends 1 arc minute (1/60 degree). The gap is 1.45mm at 5m, 0.87mm at 3m, 0.73mm at 2.5m, 0.58mm at 2m, 0.29mm at 1m, and 0.087mm at 30cm, and the outer diameter is 5 times that. A 0.5 ring is 2 times as large and a 0.1 ring is 10 times as large. The “Conversion table & standards” tab has a quick-reference table by distance.

Can I print an eye chart and use it at home?

Choose a distance (1m–5m) under “Print eye chart” to print a portrait A4 eye chart with rings from 0.1 to 2.0, sized for that distance. In the print dialog, set the scale to “100% (actual size).” If the line at the bottom measures 10cm, the rings are printed at the correct size. The 5m chart is split across 2 sheets of A4.

What vision is required to renew a driver’s license?

For ordinary, motorcycle, and semi-medium (5t limited) licenses, you need 0.7 or better with both eyes and 0.3 or better in each eye (corrected vision with glasses or contact lenses is allowed). For mopeds and small special vehicles, 0.5 or better with both eyes is required; for large, medium, semi-medium (unrestricted), and Class 2 licenses, 0.8 or better with both eyes and 0.5 or better in each eye, plus a depth perception test. After you measure the right eye, left eye, and both eyes with this tool, an estimate compared against each standard appears below the results.

What visual acuity do the school grades A, B, C, and D mean?

A is 1.0 or better, B is 0.7–0.9, C is 0.3–0.6, and D is below 0.3 (370 method). With B, small text may be hard to see from the back of the classroom; with C or D, an eye exam at an eye clinic is recommended. Results you measure at home are also shown as A–D in the results table.

What are 20/20 and 6/6 in Japanese visual acuity?

20/20 (US, feet) and 6/6 (UK, meters) both equal 1.0 in Japanese decimal acuity. The larger the denominator, the lower the acuity: 20/40 is 0.5, 20/200 is 0.1, and 20/15 is about 1.3. You can convert with decimal acuity = 20 ÷ denominator. logMAR is the negative of the common logarithm of decimal acuity, so 1.0 is 0.0 and 0.1 is 1.0.

How can I check for astigmatism at home?

Look at the radial chart in “Astigmatism check” with one eye at a time. If lines in one direction look darker or the others look blurry, you may have astigmatism. Tap the line that looks darkest, and the tool gives an estimate of the astigmatism axis using the “rule of 30” (the smaller clock number × 30). It cannot tell you the power, so if you are concerned, have it measured at an eye clinic or optician.

Are online and app-based eye tests accurate?

If the screen size and distance are correct, Landolt rings are the same size as on a real eye chart. This tool calibrates the true screen size with a card or coin, so it is more accurate than testing without calibration. However, screen brightness, contrast, and room lighting differ from an eye clinic’s test, so results can be off by about 0.1–0.2. Treat the results as an estimate.

Landolt Ring Eye Test | Home Self-Check on Phone or PC (1m–5m, True-Size Calibration), Printable A4 Eye Charts for 3m & 2.5m, Astigmatism Check, 20/20 & logMAR Conversion

The visual acuity test is a free tool that shows Landolt rings (C-shaped symbols) on your phone or computer screen so you can estimate your eyesight at home. You hold a card or coin against the screen to calibrate its true size, so at the distance you choose (30cm, or 1m–5m), the ring is drawn at the correct size where a 1.0 gap subtends 1 arc minute. Following the same rule as a real eye chart, you move to the next row after getting 3 out of 5 right, and test the right eye, left eye, and both eyes in turn. Results are shown as decimal acuity, logMAR, US-style (20/20), and Japanese school A–D grades, side by side with the driver’s license standards (ordinary license: 0.7 or better with both eyes and 0.3 or better in each eye). You can print eye charts for 3m, 2.5m, and 2m on A4 for when you don’t have a 5m room, and there is also an astigmatism radial chart (axis estimate by the “rule of 30”) and a quick-reference table of ring sizes by distance.

First, calibrate your screen to true size

To draw the Landolt ring at the correct size in mm, hold a card or coin against the screen to set “1mm on this screen.”

Distance from screen to eyes

At this distance, a 1.0 ring has an outer diameter of 2.91mm and a gap of 0.58mm. This screen can measure 0.1 to 2.0.

Eye to test

Lightly cover your left eye with your palm (don’t press). With glasses or contacts on, this is your “corrected visual acuity”; without them, it is your “uncorrected visual acuity.”

Use 8 directions including diagonals (makes lucky guesses less likely)

How to answer

Phone: Have a family member hold the screen and press the direction you call out. If you’re alone, swipe the screen toward the gap’s direction.
Computer: From a distance, use the keyboard arrow keys (numeric keypad for 8 directions; 5 or Space for “Can’t tell”).
Get 3 out of 5 right on a row to move to the next finer row; after 3 misses, the test ends. The last row you passed is your estimated visual acuity.

Results

Eye	Decimal acuity	logMAR	US-style	School grade
Right eye	—	—	—	—
Left eye	—	—	—	—
Both eyes	—	—	—	—

After you take the test, the results for your right eye, left eye, and both eyes will appear here (saved only on this device).

ABOUT

About Landolt Ring Eye Test | Home Self-Check on Phone or PC (1m–5m, True-Size Calibration), Printable A4 Eye Charts for 3m & 2.5m, Astigmatism Check, 20/20 & logMAR Conversion

The Visual Acuity Test (Landolt Ring) shows C-shaped Landolt rings on your phone or computer screen so you can estimate your eyesight at home. Because screen sizes differ from device to device, you first hold a credit card, transit IC card, or coin against the screen to set “1mm on this screen.” The tool then draws the ring at the size that matches your chosen distance (30cm, 1m, 1.5m, 2m, 2.5m, 3m, or 5m), where a 1.0 gap subtends 1 arc minute (1.45mm at 5m, 0.87mm at 3m). As on a real eye chart, getting 3 out of 5 right on a row moves you to the next smaller row, 3 misses end the test, and the last row you passed is your result. Results for the right eye, left eye, and both eyes are converted into decimal acuity, logMAR, US-style (20/20), and Japanese school A–D grades (370 method), and can be compared with driver’s license vision standards (moped: 0.5 with both eyes; ordinary: 0.7 with both eyes and 0.3 in each eye; large and Class 2: 0.8 with both eyes and 0.5 in each eye). You can also print 3m, 2.5m, and 2m eye charts on portrait A4 (with a 10cm check line) for when you don’t have a 5m room, plus an astigmatism radial chart and a quick-reference table of ring sizes by distance.

How to use Landolt Ring Eye Test | Home Self-Check on Phone or PC (1m–5m, True-Size Calibration), Printable A4 Eye Charts for 3m & 2.5m, Astigmatism Check, 20/20 & logMAR Conversion

1In “Screen size calibration,” hold a card or coin against the screen, adjust the size until the frame matches exactly, and press “Calibrate at this size”
2Choose the distance from screen to eyes (about 1m–2m for a phone, 2m–3m for a PC) and the eye to test (right, left, or both)
3Measure the distance with a tape measure, sit at that spot, lightly cover the other eye with your palm, and press “Start test”
4Answer the direction of the ring’s gap with the arrow buttons, a swipe, or the keyboard arrow keys (choose “Can’t tell” if you can’t see it)
5After testing the right eye, left eye, and both eyes, compare the results table with logMAR, 20/20, school grades, and driver’s license standards

Great for

Check at home before renewing your license whether you are likely to meet the 0.7 (both eyes) and 0.3 (each eye) standards
Check your child’s vision at home after they received a B or C grade in the school eye exam
Find out roughly whether your glasses or contact lens prescription is still right (corrected visual acuity)
Print a 3m or 2.5m eye chart on A4 because you don’t have a 5m room
Calculate the gap and outer diameter of a Landolt ring in mm from the distance
Convert overseas 20/20, 6/6, or logMAR values into Japanese decimal acuity
Check for possible astigmatism from how dark the lines look, along with an estimate of the axis
Check near vision at 30cm to see whether presbyopia has progressed

Good to know

A screen-based test is only an estimate. It cannot replace a medical diagnosis or a prescription for glasses or contact lenses. If your vision suddenly changes, only one eye is hard to see with, or things look distorted, see an eye doctor promptly.
Ring size is calculated as gap = distance × tan(1 arc minute) ÷ V for decimal acuity V (outer diameter is 5 times the gap, and stroke thickness equals the gap). Many commercial 5m eye charts round the 1.0 gap to 1.5mm, so the rings in this tool are about 3% smaller than those.
Because screen resolution is limited, rows where the gap would be finer than two device pixels are not shown. To test higher rows, increase the distance (rings can then be drawn larger). Conversely, for rows whose large rings do not fit on the screen, choose a closer distance or use a printed eye chart.
Test with the screen bright and the room well lit. Glare on the screen and the yellowish tint of night mode (blue-light filter) can make things harder to see.
Cover the other eye lightly with your palm and do not press on it. An eye that has been pressed looks blurry for a while. Squinting makes you see better than you actually do, so keep your eyes open normally when answering.
Driver’s license standards are based on Article 23 of the Enforcement Regulations of the Road Traffic Act. Large, medium, and semi-medium licenses (including Class 2) also require a three-rod depth perception test (average error within 2cm at 2.5m), which cannot be measured on a screen.
School grades follow the 370 method used in school health checks (A–D are decided using three sizes: 0.3, 0.7, and 1.0).
The screen calibration, results, and distance are saved only in this device’s browser (localStorage) and are never sent to a server. If you have already calibrated this device with the Ring Size Measurement tool, that value is used as is.

Questions this tool answers

Use Landolt Ring Eye Test | Home Self-Check on Phone or PC (1m–5m, True-Size Calibration), Printable A4 Eye Charts for 3m & 2.5m, Astigmatism Check, 20/20 & logMAR Conversion for searches like these:

I want to measure my eyesight at home with my phone
I want to check I have 0.7 vision before renewing my license
I want to print a 3m eye chart on A4
I want to calculate Landolt ring size from distance
I want to convert 20/20 vision to Japanese decimal acuity
I want to know what a B grade on the school eye exam means
I want to check for astigmatism at home
I want to check whether my near vision shows signs of presbyopia

FAQ

How far should I stand from my phone for an eye test?: For a phone, 1m–2m is recommended. At 3m or more you would need someone to hold the screen or press your answers, and at 5m the large 0.1 ring will not fit on the screen. When you choose a distance, this tool shows the range it can measure, such as “This screen can measure 0.1 to 2.0,” so use that to choose. Computer screens can have coarse pixels, so standing 2m–3m away lets finer rows be drawn.
How does the size of a Landolt ring change with distance?: A 1.0 ring is sized so that its gap subtends 1 arc minute (1/60 degree). The gap is 1.45mm at 5m, 0.87mm at 3m, 0.73mm at 2.5m, 0.58mm at 2m, 0.29mm at 1m, and 0.087mm at 30cm, and the outer diameter is 5 times that. A 0.5 ring is 2 times as large and a 0.1 ring is 10 times as large. The “Conversion table & standards” tab has a quick-reference table by distance.
Can I print an eye chart and use it at home?: Choose a distance (1m–5m) under “Print eye chart” to print a portrait A4 eye chart with rings from 0.1 to 2.0, sized for that distance. In the print dialog, set the scale to “100% (actual size).” If the line at the bottom measures 10cm, the rings are printed at the correct size. The 5m chart is split across 2 sheets of A4.
What vision is required to renew a driver’s license?: For ordinary, motorcycle, and semi-medium (5t limited) licenses, you need 0.7 or better with both eyes and 0.3 or better in each eye (corrected vision with glasses or contact lenses is allowed). For mopeds and small special vehicles, 0.5 or better with both eyes is required; for large, medium, semi-medium (unrestricted), and Class 2 licenses, 0.8 or better with both eyes and 0.5 or better in each eye, plus a depth perception test. After you measure the right eye, left eye, and both eyes with this tool, an estimate compared against each standard appears below the results.
What visual acuity do the school grades A, B, C, and D mean?: A is 1.0 or better, B is 0.7–0.9, C is 0.3–0.6, and D is below 0.3 (370 method). With B, small text may be hard to see from the back of the classroom; with C or D, an eye exam at an eye clinic is recommended. Results you measure at home are also shown as A–D in the results table.
What are 20/20 and 6/6 in Japanese visual acuity?: 20/20 (US, feet) and 6/6 (UK, meters) both equal 1.0 in Japanese decimal acuity. The larger the denominator, the lower the acuity: 20/40 is 0.5, 20/200 is 0.1, and 20/15 is about 1.3. You can convert with decimal acuity = 20 ÷ denominator. logMAR is the negative of the common logarithm of decimal acuity, so 1.0 is 0.0 and 0.1 is 1.0.
How can I check for astigmatism at home?: Look at the radial chart in “Astigmatism check” with one eye at a time. If lines in one direction look darker or the others look blurry, you may have astigmatism. Tap the line that looks darkest, and the tool gives an estimate of the astigmatism axis using the “rule of 30” (the smaller clock number × 30). It cannot tell you the power, so if you are concerned, have it measured at an eye clinic or optician.
Are online and app-based eye tests accurate?: If the screen size and distance are correct, Landolt rings are the same size as on a real eye chart. This tool calibrates the true screen size with a card or coin, so it is more accurate than testing without calibration. However, screen brightness, contrast, and room lighting differ from an eye clinic’s test, so results can be off by about 0.1–0.2. Treat the results as an estimate.

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