Lighting Design Calculator
Static · formula-only · worked example computed when this page was built · no live data
The Lighting Design Calculator uses the lumen method to find the number of luminaires needed to hit a target illuminance. Example: for a 10 × 8 m office targeting 500 lux with 40 W LED panels, at a 0.8 m work plane, in a 3 m high room, Fixtures needed = 25 fixtures, Coefficient of utilisation = 0.6, Room cavity ratio = 2.48 (per IESNA 10th Ed. | IES RP-1/7/28 | ASHRAE 90.1-2019 | PEC 2017 | DOLE D.O. 13).
How it works
Computed from your inputs per IESNA 10th Ed. | IES RP-1/7/28 | ASHRAE 90.1-2019 | PEC 2017 | DOLE D.O. 13. Anything the worked example does not state uses this calculator's standard default; the interactive version shows every input and lets you change it.
Worked example (Electrical & Power)
Inputs: a 10 × 8 m office targeting 500 lux with 40 W LED panels, at a 0.8 m work plane, in a 3 m high room.
| Result | Value |
|---|---|
| Fixtures needed | 25 fixtures |
| Coefficient of utilisation | 0.6 |
| Room cavity ratio | 2.48 |
Computed by WorkHive's calculation engine when this page was built; standard: IESNA 10th Ed. | IES RP-1/7/28 | ASHRAE 90.1-2019 | PEC 2017 | DOLE D.O. 13.
How to use this calculator
- Read the worked example. It uses a 10 × 8 m office targeting 500 lux with 40 W LED panels, at a 0.8 m work plane, in a 3 m high room and shows every number in the method.
- Follow the formula with your own figures: it returns Fixtures needed, Coefficient of utilisation, Room cavity ratio, computed per IESNA | PGBC.
- To compute interactively, open the Lighting Design Calculator inside WorkHive's free Engineering Design suite (link below). It runs the same method with your inputs.
FAQ
What is a lumen method lighting calculator lux?
The Lighting Design Calculator is a free online tool that uses the lumen method to find the number of luminaires needed to hit a target illuminance. It shows the formula and a fully worked example so you can check the method, not just the number.
How is it calculated?
The result is computed from your inputs following IESNA | PGBC. The worked example on this page shows a real computation with real numbers.
Is the calculator free?
Yes. WorkHive is free: this worked example is open to everyone, and the interactive calculator runs inside the free Engineering Design suite after a free sign-up (your work is saved to your account). WorkHive is a free, offline-first maintenance platform built for Philippine industrial plants.
Run it on your own numbers
Open the interactive Lighting Design Calculator in WorkHive. Free, and a free sign-up saves your calculations, BOMs and scope-of-works to your account.