Parking lot lighting calculator
Enter the lot, where the pole rows stand, the spacing and the mounting height. The calculator computes the illuminance on every point of a 10 ft grid and gives the minimum, average, maximum, Max:Min and Max:Avg, checked against your target and the IES parking-lot values. Or press “Find the widest spacing” and it picks the fewest evenly spaced poles per row that keep every point at or above your target.
| Minimum · average · maximum | — |
| Max:Min · Max:Avg | — |
| Every point at or above 0.2 fc | — |
| IES RP-8-25 (with 2026 errata) all parking lots, horizontal: minimum ≥ 0.2 fc, Max:Min ≤ 20 | — |
| Grid points · heads | — |
Luminaire: loading…. Horizontal illuminance at grade on a 10 ft grid, direct light only, one head per pole in a fixed orientation. Numerical checks only, not a compliance statement.
How it calculates
- Method: the point method Runnax Engine uses, E = I(γ, C) · cos θ / d² · LLF summed over every head, with intensities interpolated from the IES file.
- Luminaire: a 166 W Type III with a measured IES file, the one the engine picked for our homepage lot.
- Checked against the engine: with the engine's pole positions for the 300 × 200 ft homepage lot (“Load the engine's layout”), all 651 values match the engine's run to the three decimals it publishes.
- Widest spacing: it tries 1 to 16 poles per row, evenly spaced with the first pole half a spacing in from the end, and stops at the first count where every point meets the target.
What it doesn't do
- One luminaire only, one head per pole in a fixed orientation. Your fixtures need their own IES files.
- A rectangular lot with straight rows that you place. It does not search pole positions, heights or row layouts; that is what Runnax Engine does.
- Horizontal illuminance only, direct light only: no vertical checks, obstructions or shadowing.
- Numbers on a screen, not a photometric plan, a compliance statement or a construction approval.
For a full layout with your fixtures, where poles may stand and vertical checks, send us the lot: free parking lot photometric plan. Pole counts the engine found for other lot sizes: how many light poles a parking lot needs.
Questions
How far apart should parking lot light poles be?
It depends on the luminaire, the mounting height and the target. In our engine runs with a 166 W Type III at 29.4 to 30 ft, poles ended up 57 to 83 ft apart along a row, about 1.9 to 2.8 times the mounting height. The calculator finds the widest even spacing for your rows and target.
How do you calculate parking lot lighting?
With the point method: at each grid point, add up I(γ, C) · cos θ / d² · LLF from every luminaire, with the intensity taken from the IES file. IES RP-8-25 asks for points no farther apart than one third of the mounting height across the whole pavement; this calculator uses a 10 ft grid.
What do Max:Min and Max:Avg mean?
They describe uniformity: the brightest point divided by the darkest, or by the average. For parking lots, IES RP-8-25 (as corrected by its 2026 errata) and RP-8-18 with Addendum 1 use Max:Min 20:1 or less.
Which foot-candle target should I use?
The one your specification or local code sets. For the IES values and the 2026 errata, see our parking lot lighting requirements page.
Can I use my own fixture?
Not in this calculator, which uses one measured luminaire. Send us the IES files of the fixtures you would quote and you get a full layout with every input, free during early access.
The IES values and their sources: parking lot lighting requirements.