Mounting height changes everything about how a fixture performs: coverage diameter, beam overlap, glare risk, and uniformity. Too low creates hotspots. Too high creates dark zones between fixtures. This calculator finds the optimal mounting height for your fixture type, beam angle, and application — and shows you exactly why.
Application
Residential recessed
Even coverage priority
Office / commercial
Glare control priority
Retail
Vertical illumination
Warehouse / high bay
Uniformity priority
Accent / track
Beam focus priority
Wall washing
Vertical surface lit
Parking / outdoor
Wide coverage
Fixture Type
4″ Recessed (40°)
6″ Recessed (55°)
High Bay (90°)
High Bay wide (120°)
Floodlight (60°)
Track spot (25°)
Track flood (40°)
Wall washer (50°)
LED panel (120°)
Area light (130°)
Custom
Heights
Beam Angle
40°
Narrow (spot)Wide (flood)
Spacing (optional)
Leave at 0 to auto-calculate recommended spacing.
Single fixture
Multiple fixtures
Coverage diameter at work plane
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Recommended spacing
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Frequently Asked Questions
What is fixture mounting height and why does it matter?
Mounting height is the distance from the fixture to the work plane (floor, desk, or counter). It directly controls beam coverage diameter, light intensity at the surface, uniformity between fixtures, and glare risk. Mounting too high creates dark zones; too low creates bright hotspots with sharp shadows.
How is coverage diameter calculated from beam angle?
Coverage diameter = 2 × mounting height × tan(beam angle ÷ 2). A 9ft mounting height with a 60° beam produces a coverage diameter of 2 × 9 × tan(30°) = 2 × 9 × 0.577 = 10.4ft. This is the illuminated circle at the work plane at half the beam’s peak intensity.
What is the spacing-to-mounting-height ratio?
The spacing-to-mounting-height ratio (S/MH) describes how far apart fixtures are relative to how high they’re mounted. Values of 0.8–1.2 produce good uniformity for most applications. Below 0.5 may over-light with heavy overlap; above 1.5 creates dark zones between fixtures.
What mounting height should high bay lights be at?
High bay LED fixtures are typically mounted 15–30ft high. A 90° beam high bay at 20ft covers a 40ft diameter circle. Recommended spacing is usually 12–18ft for good uniformity. For wide-beam high bays (120°+), spacing can be slightly wider. Always check the fixture’s photometric IES data for accurate spacing criteria.
How close should recessed lights be to the wall?
For general fill lighting, the first recessed fixture is typically placed half the fixture spacing from the wall (e.g., 2–3ft from the wall if fixtures are 4–6ft apart). For wall washing, place fixtures 12–24 inches from the wall and angle them toward it, or use a dedicated wall-wash optic.
What causes glare from recessed lights?
Glare occurs when the light source (or a very bright area near it) is visible within the normal field of view. Mounting too low, using open trim with no shield, or using a narrow beam at low angles all increase glare risk. Unified Glare Rating (UGR) below 19 is the office standard. Deep-set fixtures, frosted diffusers, and higher mounting heights all reduce glare.
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