Conversion method
Photometric brightness per projected area and solid angle, weighted for human vision. Nit means cd/m²; radiometric W/m² cannot be substituted without spectral information.
fL = x × 0.2918635079601587
10 cd/m² = 2.918635 fL.
| cd/m² | fL |
|---|---|
| 1 | 0.291864 |
| 5 | 1.459318 |
| 10 | 2.918635 |
| 25 | 7.296588 |
| 50 | 14.593175 |
| 100 | 29.186351 |
Unit definitions and sources
Photometric brightness per projected area and solid angle, weighted for human vision. Nit means cd/m²; radiometric W/m² cannot be substituted without spectral information.
| Unit and system | Use | Definition | Relationship |
|---|---|---|---|
| Candela per square meter (cd/m²); si | Common units | Candela per square meter: base (cd-m2) = value × 1. Common use: Luminance. Source checked 2026-09-20 (implementation review). | Exact definition; numerical display may be rounded |
| Footlambert (fL); si | Common units | Footlambert: base (cd-m2) = value × 3.4262590996353905. Common use: Luminance. Source checked 2026-09-20 (implementation review). | Exact definition; numerical display may be rounded |
| Stilb (sb); si | Specialist units | Stilb: base (cd-m2) = value × 10000.0. Common use: Luminance. Source checked 2026-09-20 (implementation review). | Exact definition; numerical display may be rounded |
| Lambert (L); si | Specialist units | Lambert: base (cd-m2) = value × 3183.098861837907. Common use: Luminance. Source checked 2026-09-20 (implementation review). | Exact definition; numerical display may be rounded |
| Candela per square foot (cd/ft²); si | Specialist units | Candela per square foot: base (cd-m2) = value × 10.763910416709722. Common use: Luminance. Source checked 2026-09-20 (implementation review). | Exact definition; numerical display may be rounded |
| Candela/square centimeter (cd/(cm²)); other | Specialist units | candela/square centimeter = 10000.0 cd-m2, derived from the component SI/customary definitions. Common use: Luminance. Source checked 2026-09-20 (implementation review). | Exact definition; numerical display may be rounded |
| Candela/square inch (cd/(in²)); other | Specialist units | candela/square inch = 1550.0031000062002 cd-m2, derived from the component SI/customary definitions. Common use: Luminance. Source checked 2026-09-20 (implementation review). | Exact definition; numerical display may be rounded |
| Kilocandela/square meter (kcd/(m²)); other | Specialist units | kilocandela/square meter = 1000.0 cd-m2, derived from the component SI/customary definitions. Common use: Luminance. Source checked 2026-09-20 (implementation review). | Exact definition; numerical display may be rounded |
Sources: NIST: SP 811 Appendix B.8: conversion factors; BIPM: SI prefixes
Precision of luminance conversions
All 8 luminance units convert through Candela per square meter (cd/m²). 8 have an exact defined relationship to the base unit and 0 are conventional or measured values. Results and the tables on this page come from the same engine, so a table value can be checked against the converter directly.
Standard display shows up to six decimal places, switching to scientific notation for very large or small values. Calculation uses JavaScript binary floating point independently of display rounding, so extra digits are not a claim about measurement accuracy. Each unit lists its own source; a citation records where the definition comes from, not an independent review. See Conversion methodology for the review and correction process.