Lighting Design Calculator
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, Fixtures needed = 20.52 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.
Worked example (Electrical & Power)
Inputs: a 10 × 8 m office targeting 500 lux with 40 W LED panels.
| Result | Value |
|---|---|
| Fixtures needed | 20.52 fixtures |
| Coefficient of utilisation | 0.6 |
| Room cavity ratio | 2.48 |
Computed live by WorkHive's calculation engine; standard: IESNA 10th Ed. | IES RP-1/7/28 | ASHRAE 90.1-2019 | PEC 2017 | DOLE D.O. 13.
How to use this calculator
- Enter the figures for the duty you are sizing: the worked example below uses a 10 × 8 m office targeting 500 lux with 40 W LED panels.
- The calculator returns Fixtures needed, Coefficient of utilisation, Room cavity ratio, computed per IESNA | PGBC.
- Check the worked example to confirm the method matches how you would do it by hand, then run your own numbers in the interactive tool.
FAQ
What is a lumen method lighting calculator lux?
The Lighting Design Calculator is a free online tool that computes 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's engineering calculators are free to use, no sign-up needed for the tools. 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, no sign-up needed for the calculators.