Room lighting calculator using the lumen method
Estimate how many luminaires a room needs to reach a target maintained illuminance, or check what average lux an existing layout should deliver. The calculation follows the standard lumen method: E = (N × F × UF × MF) ÷ A.
Floor area: 96 m²
23 luminaires needed
Planning estimate only. Uniformity, glare (UGR) and the real light reaching each task area can only be confirmed by measurement.
Choosing UF and MF
- Utilisation factor is the share of lamp lumens that reaches the working plane. Small or dark rooms are about 0.3–0.45. Large, light-coloured open-plan spaces are about 0.6–0.75. Manufacturers publish UF tables for each luminaire.
- Maintenance factor allows for lumen depreciation and dirt over the maintenance cycle. About 0.8 suits clean LED offices. Dusty warehouses and kitchens may need 0.6–0.7.
The target values for each space are in our recommended lux levels chart. To prove the finished installation complies, book a lux survey.