Transmittance to absorbance
Type a value in T to get it in A instantly.
0A
Nothing on our list is smaller: a clean blank is 1.02× darker. About 100% of the light gets through.
What it means
How much light gets through?
Above about 2 the detector is measuring very little light, and stray light dominates. Dilute the sample rather than trusting the reading.
The math
How to convert T to A
Absorbance is a logarithm of transmittance: A = −log₁₀(T), and back again %T = 10^(−A) × 100. One absorbance unit is a tenfold cut.
Example: 1 T = 0 A.
Every unit
Your absorbance in every unit
Tables
T to A conversion table
| T | A |
|---|---|
| 0.0001 T | 4 A |
| 0.001 T | 3 A |
| 0.01 T | 2 A |
| 0.0316 T | 1.50031 A |
| 0.1 T | 1 A |
| 0.2 T | 0.69897 A |
| 0.316 T | 0.500313 A |
| 0.501 T | 0.300162 A |
| 0.794 T | 0.100179 A |
| 0.891 T | 0.0501223 A |
| 0.977 T | 0.0101054 A |
A to T conversion table
| A | T |
|---|---|
| 0.01 A | 0.977237 T |
| 0.05 A | 0.891251 T |
| 0.1 A | 0.794328 T |
| 0.3 A | 0.501187 T |
| 0.5 A | 0.316228 T |
| 0.7 A | 0.199526 T |
| 1 A | 0.1 T |
| 1.5 A | 0.0316228 T |
| 2 A | 0.01 T |
| 3 A | 0.001 T |
| 4 A | 1×10⁻⁴ T |
Quick answers
Quick answers
- How many A is 1 T?
- 1 T is 0 A.
The units
About these units
Transmittance (T)
The same fraction, from 0 to 1.
Absorbance (A)
The base-ten logarithm of what is blocked. Proportional to concentration.
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