LED Lighting Layout Calculator
A working first pass at a fixture count. Tell it what the space is and how big it is, and it will give you a quantity, a layout drawing with the spacing marked, and a rough fixture cost. It uses the lumen method, the same arithmetic a real lighting layout starts from.
20,000 square feet
Suggested layout
What the numbers mean
The calculation is the lumen method. Target foot candles multiplied by floor area gives the light you need on the floor. That gets divided by a coefficient of utilization, which accounts for the light that never reaches the floor because it lands on walls and racking, and by a light loss factor, which accounts for the fixture getting dirty and the LEDs dimming over their life. The result is the installed lumens you have to buy, which divided by the output of one fixture gives the count.
The light loss factor is why the number comes out higher than a bare foot candle calculation. A fixture does not put out its day one lumens in year seven, and nobody washes high bays. Designing to the exact target means the building is under lit for most of its life.
The drawing then rounds that count into a grid that actually fits the building, because you hang fixtures in rows, not in a fraction of a row. That usually moves the number by one or two.
Foot candle targets this uses
| Space | Foot candles | Notes |
|---|---|---|
| Warehouse, bulk storage | 10 | Pallet in, pallet out, little reading |
| Warehouse, picking | 30 | Label reading at the rack face |
| Manufacturing | 50 | General assembly, raise it for fine work |
| Auto shop | 50 | Under hood work needs task light on top |
| Gymnasium | 30 | Recreational play, competition runs higher |
| Cold storage | 20 | Check the fixture is rated for the temperature |
| Office, open plan | 30 | Screen work, not paper work |
| Classroom | 40 | Measured at the desk |
| Retail | 50 | Sales floor, accent lighting is separate |
| Corridor | 10 | Egress minimums are lower |
| Parking garage | 5 | Uniformity matters more than the average |
Where this stops being enough
This is a budget number and a sanity check, not a photometric layout. It assumes an open rectangular space with a regular grid and no obstructions. It does not know about your racking, your column spacing, skylights, wall colour, or where the aisles run.
Racking is the big one. In a racked warehouse the aisle is a canyon, and a fixture centred over a rack puts most of its light on the top of the pallets. Aisle lit layouts use narrow beam optics run down the aisle rather than a uniform grid, and the count changes.
Send us the building and we will run the real thing. A dimensioned floor plan, the ceiling height and the racking layout is enough for a proper photometric with foot candle contours. No charge, and no obligation to buy the fixtures from us.
Related
Sizing a warehouse high bay layout walks through the same method by hand, including spacing to mounting height ratios and the beam angle decision racking forces on you. Metal halide equivalents covers what to replace an existing fixture with if you are going one for one.