Luminance / asb → sb
Convert Apostilbs to Stilbs
Convert visible-light luminance in candela per projected area. Convert Apostilbs (asb) to Stilbs (sb). Find the formula, worked examples, unit definitions, and practical guidance below.
Reverse: Stilbs to Apostilbs →
How to convert apostilbs to stilbs
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 asb, b for the intermediate value in cd/m², and y for the result in sb.
sb = asb × 0.3183098861837907 ÷ 10000
Worked examples
10 asb ≈ 0.000318309886184 sb
Step 1: (10 × 0.318309886184) ≈ 3.18309886184 cd/m².
Step 2: 3.18309886184 ÷ 10000 ≈ 0.000318309886184 sb.20 asb ≈ 0.000636619772368 sb
Step 1: (20 × 0.318309886184) ≈ 6.36619772368 cd/m².
Step 2: 6.36619772368 ÷ 10000 ≈ 0.000636619772368 sb.
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 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.
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.
Definitions and sources
Carry the same physical assumptions into subsequent physics calculations.
Apostilbs to stilbs reference table
| Apostilbs (asb) | Stilbs (sb) |
|---|---|
| 1 | 0.0000318309886184 |
| 5 | 0.000159154943092 |
| 10 | 0.000318309886184 |
| 25 | 0.000795774715459 |
| 50 | 0.00159154943092 |
| 100 | 0.00318309886184 |
| 1000 | 0.0318309886184 |
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