UV Curing calculator

UV Exposure Time Calculator

Process engineers and lab techs use this when commissioning a new UV chemistry, validating a static fixture, or tuning a step-and-repeat cure cell. Plug in the dose your adhesive, ink, or coating data sheet calls for and the irradiance you read at the part with a calibrated radiometer; the calculator returns the dwell seconds plus a margin so a weak lamp or dirty quartz doesn't push you under-cure.

What this calculator does

  • Solve for the seconds of UV exposure needed to deliver a target dose at a measured irradiance, with a safety margin baked in.
  • Use it before a static cure or batch fixture run when you know the dose the chemistry needs and the irradiance your lamp is putting out at the work surface.
  • Returns the seconds the part has to sit under the lamp to receive the dose your chemistry needs, padded by the safety margin you set.

Formula used

  • Base exposure (sec) = required dose (mJ/cm²) ÷ measured irradiance (mW/cm²)
  • Recommended exposure = base exposure × (1 + safety margin %)

Inputs explained

  • Required dose: From the chemistry data sheet at the relevant UV band (UVA, UVV, etc.).
  • Measured irradiance at part: Read with a calibrated radiometer at the actual part surface, not the lamp face.
  • Safety margin: Cushion for lamp aging, quartz fouling, and irradiance falloff between checks.

How to use the result

  • Reach for it when commissioning a new UV adhesive or coating, validating a static cure fixture, or recovering after a lamp swap when irradiance has shifted.
  • Assumes the irradiance reading is at the actual cure surface and stays steady through the dwell. It does not model lamp warm-up, oxygen inhibition, shadowing, or substrate absorbance — handle those with the dedicated calcs in the related list.

Common questions

  • Why divide dose by irradiance to get cure time? Dose is energy per area (mJ/cm²) and irradiance is power per area (mW/cm² = mJ/sec/cm²). The mJ/cm² values cancel and you are left with seconds. If your radiometer reports W/cm² instead of mW/cm², multiply your reading by 1,000 before entering it.
  • What safety margin should I use? 20–30% is typical for production UV lines, where lamp output drifts down between scheduled radiometer checks. Tighten to 10–15% if you radiometer every shift; widen to 40–50% on equipment with no scheduled monitoring or where the part geometry creates shadowing.
  • My calculated time is way longer than the data sheet — why? Almost always because the irradiance at the part is lower than assumed: lamp aging, quartz fouling, focal distance off, wrong UV band on the radiometer, or the radiometer was on the lamp face instead of the part. Re-measure with a clean, calibrated radiometer at the cure plane and re-run.
  • Does this apply to UV LED systems? Yes — the math is the same. Just make sure the radiometer's spectral response matches your LED's peak (385, 395, 405 nm, etc.) and that the chemistry's dose target was specified for that wavelength. Mismatched bands are the most common source of surprise undercure on LED retrofits.

Last reviewed 2026-05-12.