Focal length in centimeters to diopters
Type a value in cm to get it in D instantly.
50D
That's 4.2× as strong as a hand magnifier, while the human eye is 1.18× stronger. That brings light to a focus about 20 mm away.
Convert the other way: D to cm
What it means
How strong is that lens?
Prescriptions carry a cylinder and an axis as well, for astigmatism. This page converts the sphere, which is the main number.
The math
How to convert cm to D
Power and focal length are reciprocals: diopters = 1 ÷ focal length in meters, so focal length in mm = 1000 ÷ diopters.
Example: 2 cm = 50 D.
Every unit
Your lens in every unit
Tables
cm to D conversion table
| cm | D |
|---|---|
| 0.25 cm | 400 D |
| 0.5 cm | 200 D |
| 1 cm | 100 D |
| 1.5 cm | 66.6667 D |
| 2 cm | 50 D |
| 2.5 cm | 40 D |
| 3 cm | 33.3333 D |
| 4 cm | 25 D |
| 6 cm | 16.6667 D |
| 10 cm | 10 D |
| 20 cm | 5 D |
D to cm conversion table
| D | cm |
|---|---|
| 0.25 D | 400 cm |
| 0.5 D | 200 cm |
| 1 D | 100 cm |
| 1.5 D | 66.6667 cm |
| 2 D | 50 cm |
| 2.5 D | 40 cm |
| 3 D | 33.3333 cm |
| 4 D | 25 cm |
| 6 D | 16.6667 cm |
| 10 D | 10 cm |
| 20 D | 5 cm |
Quick answers
Quick answers
- How many D is 1 cm?
- 1 cm is 100 D.
- How many D is 10 cm?
- 10 cm is 10 D.
- How many D is 2 cm?
- 2 cm is 50 D.
The units
About these units
Focal length in centimeters (cm)
The handy scale for magnifiers and close-up lenses.
Diopters (D)
One divided by the focal length in meters. Diopters simply add.
Keep going