Conversion Tool: Transmission ↔ Optical Density
Calculate optical density from transmittance, or vice versa
Here, you can convert optical density to transmittance and vice versa. It is a helpful online app to calculate the transmittance or optical density of a neutral density filter.
Common values (click a row to use)
| Transmission | Optical Density |
|---|---|
| 100 % | 0 |
| 79.433 % | 0.1 |
| 50.119 % | 0.3 |
| 31.623 % | 0.5 |
| 10 % | 1 |
| 3.162 % | 1.5 |
| 1 % | 2 |
| 0.1 % | 3 |
| 0.01 % | 4 |
| 0.001 % | 5 |
| 0.0001 % | 6 |
How is this calculated?
Optical density (OD) describes the base-10 logarithm of the ratio between incident and transmitted light intensity. A logarithmic scale is used because transmission can vary across many orders of magnitude and would be unwieldy on a linear scale.
Formulas:
Where T is the transmittance in percent (0–100%) and OD is the optical density (dimensionless, ≥ 0).
Example: A transmission of 1% gives an OD of 2, because log10(100 / 1) = log10(100) = 2. Conversely, OD 3 corresponds to a transmission of 0.1%, since 100 / 103 = 0.1.
Note: No warranty or liability is assumed for the accuracy of the results.
If you like this tool, we invite you to place a direct link to this calculator on your website.
Use our SCHOTT Filter Calculator v2.0
Our updated online calculation tool for the transmission of all available ND filters as well as all SCHOTT colored glass filters is now available. You can plot individual or multiple filters in a single curve or calculate filter combinations.
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Last update: April 16, 2026