Luminance / sb → asb
Convert Stilbs to Apostilbs
Convert visible-light luminance in candela per projected area. Convert Stilbs (sb) to Apostilbs (asb). Find the formula, worked examples, unit definitions, and practical guidance below.
Reverse: Apostilbs to Stilbs →
How to convert stilbs to apostilbs
Luminance describes directional brightness weighted for human vision. It differs from illuminance on a surface and cannot be converted to lux without geometry.
Use x for the value in sb, b for the intermediate value in cd/m², and y for the result in asb.
asb = sb × 10000 ÷ 0.3183098861837907
Worked examples
10 sb ≈ 314159.265359 asb
Step 1: (10 × 10000) ≈ 100000 cd/m².
Step 2: 100000 ÷ 0.318309886184 ≈ 314159.265359 asb.20 sb ≈ 628318.530718 asb
Step 1: (20 × 10000) ≈ 200000 cd/m².
Step 2: 200000 ÷ 0.318309886184 ≈ 628318.530718 asb.
Results are rounded to 12 significant digits. Converting units does not increase the precision of the original measurement. Very large or small values outside JavaScript’s finite numeric range are rejected.
About Stilbs
Stilbs (sb) measures luminance under the conventions above. The base value in cd/m² is (x × 10000), where x is the numerical value in sb. Factors shown here are rounded for display; calculations use the stored factor.
About Apostilbs
Apostilbs (asb) measures luminance under the conventions above. The base value in cd/m² is (x × 0.318309886184), where x is the numerical value in asb. Factors shown here are rounded for display; calculations use the stored factor.
Definitions and sources
Carry the same physical assumptions into subsequent physics calculations.
Stilbs to apostilbs reference table
| Stilbs (sb) | Apostilbs (asb) |
|---|---|
| 1 | 31415.9265359 |
| 5 | 157079.632679 |
| 10 | 314159.265359 |
| 25 | 785398.163397 |
| 50 | 1570796.32679 |
| 100 | 3141592.65359 |
| 1000 | 31415926.5359 |
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