Does 96% area coverage block 96% of the UV?

No. What escapes through an open aperture passes at full strength in a fixed direction. The hazard therefore depends on where it points, not on its share of the area.

What material should a UV guard be?

One specified for attenuation at the wavelengths present. Visible opacity says little: some solid-looking plastics pass appreciable UV while clear acrylics block it.

How do I deal with conveyor slots?

Force the light to take turns it cannot follow. Baffles, labyrinth entries, brush seals and longer tunnels attenuate by repeated reflection, then measure what still escapes.

Is coverage efficiency an attenuation figure?

No. It is a take-off allowance for seam overlaps, fixings and trim waste, so it tells you how much material to order, not how well it works.

UV Curing calculator

UV Shielding Calculator: Area to Buy, and the Gaps That Decide It

Size the guard material a UV cell needs, then look at the aperture that stays open. Enter the face area, exposed sides, take-off efficiency and the openings the process needs.

What this calculator does

Guard area to buy for a UV cell, with the aperture left open stated separately from the coverage.

Formula used

Theoretical shield area = open face area × exposed sides
Shielding area required = theoretical area ÷ coverage efficiency
Overlap and cut-out allowance = required area − theoretical area
Aperture left open (%) = openings ÷ theoretical area × 100
Face area actually covered = theoretical area − openings

Inputs explained

Open UV Emission Face Area: Area of one face through which UV can escape.
Exposed Sides to Guard: Faces a person can occupy, including during maintenance.
Guard Coverage Efficiency: Purchased material that becomes effective coverage after overlap.
Openings Left Open: Conveyor slots, windows and access gaps that cannot be closed.

How to use the result

Best suited to estimating guard material for a cell enclosure, quantifying the aperture a design leaves open, justifying baffles on conveyor apertures.
A material take-off, not a safety assessment; attenuation is measured, not calculated. Says nothing about the guard material's UV transmission at your wavelengths. Treats openings as one area, when where each one points matters most.

Common questions

Does 96% area coverage block 96% of the UV? No. What escapes through an open aperture passes at full strength in a fixed direction. The hazard therefore depends on where it points, not on its share of the area.
What material should a UV guard be? One specified for attenuation at the wavelengths present. Visible opacity says little: some solid-looking plastics pass appreciable UV while clear acrylics block it.
How do I deal with conveyor slots? Force the light to take turns it cannot follow. Baffles, labyrinth entries, brush seals and longer tunnels attenuate by repeated reflection, then measure what still escapes.
Is coverage efficiency an attenuation figure? No. It is a take-off allowance for seam overlaps, fixings and trim waste, so it tells you how much material to order, not how well it works.

Last reviewed 2026-10-01.