High Bay Lighting Layout Guide: Spacing, Mounting and Lux Calculation

A high bay layout stands on three numbers: mounting height, fixture spacing and the lumen package. Get them proportionate and a 200 lx warehouse arrives on the first fixture count; get them wrong and you discover dark bands between fittings only after the electricians leave. This guide collects the spacing rules of thumb used in export project quotations, the two-step calculation behind them, and the beam-angle logic that decides whether they hold. Every figure is a typical planning value for UFO and linear LED high bays at 130-150 lm/W — final layouts should be confirmed in dialux or relux before production.

Spacing and lumen packages by mounting height

Illustrative values for open-plan areas with 60-90 deg optics at 130-150 lm/W, targeting 150-200 lx. Racking aisles use dedicated optics and tighter spacing regardless of height — see the caution list below.

The two-step calculation behind the table

Step 1 — how many fixtures. The lumen method: N = (E x A) / (F x UF x MF). For a 60 x 30 m warehouse bay at 200 lx (E), 1,800 m² (A), 16,000 lm UFOs (F), utilisation factor 0.8 and maintenance factor 0.8: N = 360,000 / (16,000 x 0.64) = 35.2, so 36 fixtures — a 9 x 4 grid.

Step 2 — where they go. Space them against mounting height, not just area. For wide-beam high bays, spacing S = 1.0-1.2 x H holds uniformity above 0.4; at 8 m mounting that allows 8-9.6 m centres, comfortably matching the 6 x 5 m grid a 36-fixture layout needs in this example. Keep the first fixture 0.5-1.0 x S from the walls — halving edge spacing (S/2) is the classic rule for perimeter rows. If the grid demands spacing beyond 1.2 x H, either raise the lumen package or tighten the grid; never widen it.

Beam angle by mounting height

Practical cautions

• Distrust spacing claims above 1.5 x H. Fixture datasheets love "spacing-to-height ratio 1.6" — layouts that use it typically pass average lux and fail uniformity. 1.0-1.2 is the honest open-area range.
• Rack aisles are their own design. Aisle optics throw sideways onto rack faces; reusing wide-beam open-area layouts there wastes 30-40% of the flux on the floor.
• Check obstruction shadows. Racks, crane rails and ducting split the space — place fixtures between rack rows and re-run uniformity per aisle, not per building.
• Mounting height means the fixture, not the roof. Fixtures hung on drop tubes 2 m below the rafters design at the drop height, and the spacing table moves accordingly.
• Sensors change both numbers. Aisle-by-aisle occupancy dimming lets you run 200 lx when open and 30% when empty — worth it from roughly 20 fixtures upward.

From layout to quotation

Send the floor plan, mounting height and target lux, and the layout returns a fixture schedule with grid positions, beam angles and estimated energy use per zone. The UFO and linear ranges under warehouse lighting cover the 9,000-36,000 lm band in the table, with aisle optics available on request; heavier 15-20 m applications draw on the industrial lighting programme. For the standards and arithmetic in more depth, our warehouse lighting design guide walks a full project end to end, and the UFO vs linear comparison settles which body suits your aisles.