Live Demo — Lighting Coverage Calculator
Enter mounting height, beam and tilt angles plus road geometry to see coverage area, average illuminance and spacing verification instantly.
Lighting Coverage Calculator
Free professional road lighting coverage calculator for solar lighting projects. Input mounting height, longitudinal and transverse beam angles, luminaire tilt and flux, plus road width, spacing and arrangement, to compute the covered length, width and area, verify that adjacent lamps overlap without dark areas, and estimate the resulting average illuminance and uniformity.
Key Features
Luminaire & Installation
Set the mounting height, longitudinal and transverse beam angles, luminaire tilt (5-15° typical) and total luminous flux.
Road Geometry & Arrangement
Define road width, pole spacing and arrangement mode (one-side, staggered, or opposite) that matching your layout.
Longitudinal Coverage
Compute the coverage length along the road with L = 2 × h × tan α_v so you can judge overlap between adjacent beams.
Transverse Coverage & Tilt
Derive the full width covered across the road, including how arm tilt shifts the beam toward the inner side of the carriageway.
Spacing Verification
Check that pole spacing keeps longitudinal beam spots overlapping by ≥1/3 and satisfies the S/h ≤ 4 spacing rule, flagging dark areas.
Illuminance & Uniformity
Estimate average illuminance (E = Φ × CU × MF / A) over the covered area and compare it against the target and S/h reference table.
Technical Specifications
| Platform | HTML5 Web App | Android (via WebView) |
| Core Calculation | L = h × tan α_v × 2; B = h × (tan(α_h + θ_tilt) + tan(α_h - θ_tilt)); A = L × B; E_avg = Φ × CU × MF / A; S ≤ L × overlap |
| Mounting Height | 7+ ft (13-39 ft typical) |
| Longitudinal Beam Angle | 10° - 180° (wide-beam 110-140°) |
| Transverse Beam Angle | 10° - 180° (wide-beam 70-120°) |
| Luminaire Tilt | -15° to +30° (arm tilt 5-15°) |
| Luminaire Flux | 1,000+ lm |
| Road Width / Spacing | 3+ ft / 16+ ft |
| Arrangement | One-side / Staggered (two sides) / Opposite (two sides) |
| Spacing-to-Height Ratio | S/h ≤ 4 (general roads), ≤3.5 (arterial/secondary) |
| Industry Standards | EN 13201, IES RP-8-18 |
| Output | Coverage length (ft), width (ft), area (ft²), average illuminance (fc), spacing/overlap pass & fail status |
Frequently Asked Questions
How is the longitudinal coverage length computed?
A lamp lights a beam spot twice the height times the tangent of its half longitudinal beam angle: L = h × tan(α_v) × 2. This length is compared with the neighbouring pole spacing to confirm the beam spots overlap and the road stays continuously lit.
Why does the transverse coverage formula use the tilt angle?
The transverse width combines the beam edges on both sides: B = h × (tan(α_h + θ_tilt) + tan(α_h - θ_tilt)). Tilting the arm shifts the beam toward the inner side of the road, so light aimed inward stays on the carriageway while the outer-side reach shrinks.
How do I know my spacing avoids dark areas?
The calculator applies two checks: adjacent longitudinal beam spots must overlap by at least one third, and the spacing-to-height ratio must stay within S/h ≤ 4 (general roads). If either check fails, the spacing is flagged so you can reduce it until coverage is continuous.
Why are wide-beam optics recommended for solar lighting?
Solar street lights are limited by battery capacity, so designers aim for the lower bound of uniformity. Wide-beam photometric control (transverse 70-120°) lets fewer poles cover more road continuously, reducing the number of luminaires and overall system cost while still meeting illuminance standards.
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