Snellen (feet) to decimal acuity
Type a value in Snellen (ft) to get it in decimal instantly.
1decimal
That's about the same as normal vision (20/20). What a normal eye reads at 20 ft (6 m), this eye reads from about 20 ft (6 m).
Convert the other way: decimal to Snellen (ft)
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 (ft) to decimal
Decimal = 20 ÷ x for 20/x, or 6 ÷ x for 6/x; logMAR = −log₁₀(decimal); ETDRS letters = 85 − 50 × logMAR.
Example: 20/20 Snellen (ft) = 1 decimal.
Every unit
That eyesight in every notation
Tables
Snellen (ft) to decimal conversion table
| Snellen (ft) | decimal |
|---|---|
| 20/10 Snellen (ft) | 2 decimal |
| 20/15 Snellen (ft) | 1.33333 decimal |
| 20/20 Snellen (ft) | 1 decimal |
| 20/25 Snellen (ft) | 0.8 decimal |
| 20/30 Snellen (ft) | 0.666667 decimal |
| 20/40 Snellen (ft) | 0.5 decimal |
| 20/50 Snellen (ft) | 0.4 decimal |
| 20/60 Snellen (ft) | 0.333333 decimal |
| 20/70 Snellen (ft) | 0.285714 decimal |
| 20/80 Snellen (ft) | 0.25 decimal |
| 20/100 Snellen (ft) | 0.2 decimal |
| 20/200 Snellen (ft) | 0.1 decimal |
| 20/400 Snellen (ft) | 0.05 decimal |
decimal to Snellen (ft) conversion table
| decimal | Snellen (ft) |
|---|---|
| 0.05 decimal | 20/400 Snellen (ft) |
| 0.1 decimal | 20/200 Snellen (ft) |
| 0.2 decimal | 20/100 Snellen (ft) |
| 0.25 decimal | 20/80 Snellen (ft) |
| 0.286 decimal | 20/70 Snellen (ft) |
| 0.333 decimal | 20/60 Snellen (ft) |
| 0.4 decimal | 20/50 Snellen (ft) |
| 0.5 decimal | 20/40 Snellen (ft) |
| 0.667 decimal | 20/30 Snellen (ft) |
| 0.8 decimal | 20/25 Snellen (ft) |
| 1 decimal | 20/20 Snellen (ft) |
| 1.33 decimal | 20/15 Snellen (ft) |
| 2 decimal | 20/10 Snellen (ft) |
Quick answers
Quick answers
- How many decimal is 20/1 Snellen (ft)?
- 20/1 Snellen (ft) is 20 decimal.
- How many decimal is 20/10 Snellen (ft)?
- 20/10 Snellen (ft) is 2 decimal.
- How many decimal is 20/20 Snellen (ft)?
- 20/20 Snellen (ft) is 1 decimal.
The units
About these units
Snellen (feet) (Snellen (ft))
The US fraction: 20 feet over the normal distance.
Decimal acuity (decimal)
The Snellen fraction as a number: 20/40 = 0.5. Used in Europe.
Keep going