How do you calculate UV dose uniformity?

Map dose at a grid of points, take the max, min, and average, then compute spread as max minus min and variation as spread divided by average times 100. In the example, 1450 minus 950 is a 500 mJ/cm2 spread, which over a 1180 average is about 42.4% variation.

What is a good UV dose uniformity number?

Tighter is better; many coating processes aim for variation under 10 to 15 percent of average. The example at 42.4% is very non-uniform and points to reflector, lamp-end, or geometry problems that need correction.

Where should I put my grid points?

Cover the full part width and length, and always include the edges and any shadowed features, because the cold spot usually lives at the edges or corners where the map, and cure, fail first.

Spread vs variation percent, which do I report?

Report both. The 500 mJ/cm2 spread is the absolute gap; the 42.4% variation normalizes it against the average so you can compare parts and lamps of different dose levels.

Why does my part edge undercure while the center is fine?

Lamp end-effects and reflector geometry drop irradiance at the extremes of the working width, so edges sit at the cold spot. Mapping reveals it; the fix is usually reflector cleaning, lamp repositioning, or masking down to the good zone.

What causes uniformity to get worse over time?

Reflector fouling and uneven lamp aging are the usual culprits. Both pull down specific grid points, widening the spread even when the average dose still looks acceptable.

UV Curing calculator

UV Dose Mapping Calculator

Dose mapping checks how evenly UV energy lands across the working width of a lamp or across a part, by measuring dose at a grid of points. This calculator takes the coldest, hottest, and average dose from that grid and reports the absolute spread and the variation as a percent of the average. Process engineers use it to catch reflector fouling, lamp end-effects, and part-shadowing before they cause edge undercure. A tight spread means every location on the part cures the same; a wide spread means some areas are starving while others overcure.

What this calculator does

Take grid-pass radiometer readings and reduce them to the dose spread, max-to-min range, and a quick variation-from-average percent.
Use it after a profiling pass to quantify spatial dose variation across a fixture, belt width, or batch oven floor.
It computes the dose spread (max minus min) across your grid and the variation from average as a percentage.

Formula used

Dose spread = max − min (mJ/cm²)
Variation from average (%) = spread ÷ average × 100

Inputs explained

Coldest grid-point dose (cold spot):
Hottest grid-point dose (hot spot):
Average dose across the grid:

How to use the result

Use it after a lamp or reflector change, during periodic uniformity checks, or when only part of a product shows cure defects.
The result is only as good as your grid; too few points, or points that miss the true cold spot at part edges, will understate the real spread.

Common questions

How do you calculate UV dose uniformity? Map dose at a grid of points, take the max, min, and average, then compute spread as max minus min and variation as spread divided by average times 100. In the example, 1450 minus 950 is a 500 mJ/cm2 spread, which over a 1180 average is about 42.4% variation.
What is a good UV dose uniformity number? Tighter is better; many coating processes aim for variation under 10 to 15 percent of average. The example at 42.4% is very non-uniform and points to reflector, lamp-end, or geometry problems that need correction.
Where should I put my grid points? Cover the full part width and length, and always include the edges and any shadowed features, because the cold spot usually lives at the edges or corners where the map, and cure, fail first.
Spread vs variation percent, which do I report? Report both. The 500 mJ/cm2 spread is the absolute gap; the 42.4% variation normalizes it against the average so you can compare parts and lamps of different dose levels.
Why does my part edge undercure while the center is fine? Lamp end-effects and reflector geometry drop irradiance at the extremes of the working width, so edges sit at the cold spot. Mapping reveals it; the fix is usually reflector cleaning, lamp repositioning, or masking down to the good zone.

Last reviewed 2026-05-12.