Snellen (meters) to decimal acuity
Type a value in Snellen (m) to get it in decimal instantly.
0.3decimal
That's 3× as sharp as the US legal blindness limit (20/200), while the usual driving minimum (20/40) is 1.67× sharper. What a normal eye reads at 20 ft (6 m), this eye reads from about 6 ft (1.8 m).
What it means
How sharp is that?
For information only: an eye test also depends on the chart, lighting and the examiner. Ask an optometrist about your own eyes.
The math
How to convert Snellen (m) to decimal
Decimal = 20 ÷ x for 20/x, or 6 ÷ x for 6/x; logMAR = −log₁₀(decimal); ETDRS letters = 85 − 50 × logMAR.
Example: 6/20 Snellen (m) = 0.3 decimal.
Every unit
That eyesight in every notation
Tables
Snellen (m) to decimal conversion table
| Snellen (m) | decimal |
|---|---|
| 6/10 Snellen (m) | 0.6 decimal |
| 6/15 Snellen (m) | 0.4 decimal |
| 6/20 Snellen (m) | 0.3 decimal |
| 6/25 Snellen (m) | 0.24 decimal |
| 6/30 Snellen (m) | 0.2 decimal |
| 6/40 Snellen (m) | 0.15 decimal |
| 6/50 Snellen (m) | 0.12 decimal |
| 6/60 Snellen (m) | 0.1 decimal |
| 6/70 Snellen (m) | 0.0857143 decimal |
| 6/80 Snellen (m) | 0.075 decimal |
| 6/100 Snellen (m) | 0.06 decimal |
| 6/200 Snellen (m) | 0.03 decimal |
| 6/400 Snellen (m) | 0.015 decimal |
decimal to Snellen (m) conversion table
| decimal | Snellen (m) |
|---|---|
| 0.05 decimal | 6/120 Snellen (m) |
| 0.1 decimal | 6/60 Snellen (m) |
| 0.2 decimal | 6/30 Snellen (m) |
| 0.25 decimal | 6/24 Snellen (m) |
| 0.286 decimal | 6/21 Snellen (m) |
| 0.333 decimal | 6/18 Snellen (m) |
| 0.4 decimal | 6/15 Snellen (m) |
| 0.5 decimal | 6/12 Snellen (m) |
| 0.667 decimal | 6/9 Snellen (m) |
| 0.8 decimal | 6/7.5 Snellen (m) |
| 1 decimal | 6/6 Snellen (m) |
| 1.33 decimal | 6/4.5 Snellen (m) |
| 2 decimal | 6/3 Snellen (m) |
Quick answers
Quick answers
- How many decimal is 6/1 Snellen (m)?
- 6/1 Snellen (m) is 6 decimal.
- How many decimal is 6/10 Snellen (m)?
- 6/10 Snellen (m) is 0.6 decimal.
- How many decimal is 6/20 Snellen (m)?
- 6/20 Snellen (m) is 0.3 decimal.
The units
About these units
Snellen (meters) (Snellen (m))
The UK and metric fraction: 6 meters over the normal distance.
Decimal acuity (decimal)
The Snellen fraction as a number: 20/40 = 0.5. Used in Europe.
Keep going