UV Curing calculator

UV Lamp Life Remaining Calculator

Mercury and metal-halide UV lamps have a rated useful life (often 1,000–4,000 hours) after which output has dropped enough to risk undercure even at minimum line speed. This calculator projects how many production days remain on the current lamp given the hours it has run and the hours per day the line is using it, plus a safety multiplier that pulls the swap date forward to give purchasing and maintenance time to react.

What this calculator does

  • Project days until the next UV lamp swap from rated hours, hours already on the lamp, and current runtime per day.
  • Use it to schedule lamp replacements proactively (before they cause undercure) instead of reactively (after a quality escape).
  • Returns days of remaining lamp life with and without a safety pull-forward, so you can plan spares and downtime windows around the planned swap.

Formula used

  • Days remaining (raw) = useful life remaining ÷ average daily runtime
  • Planned swap day = days remaining (raw) ÷ safety multiplier

Inputs explained

  • Useful life remaining: Rated useful life from the lamp data sheet minus hours already accumulated on the hour meter.
  • Average daily runtime: Energized lamp hours per production day, averaged over the past 2–4 weeks.
  • Safety factor: Pulls the planned swap forward; 1.2× = swap at ~83% of rated life.

How to use the result

  • Run it weekly on every UV line and after any change in production schedule (added shift, new high-volume program) that bumps the daily runtime number.
  • Lamp end-of-life is dose-limited, not just hour-limited. A lamp that has been over-cycled (frequent on/off), run with bad cooling, or used past 80% of rated life will lose output faster than the linear model assumes. Pair this with the UV Dose Margin calc to confirm the lamp is still hitting the dose target — never run on hours alone.

Common questions

  • Where do I find rated useful life? On the lamp data sheet — usually quoted as the hours at which output drops to 70–80% of new. Mercury arcs are typically 1,000–4,000 hr; doped metal-halide can be 600–2,000 hr; LED arrays are spec'd in tens of thousands of hours and need a different model entirely.
  • What safety multiplier should I use? 1.1–1.3× is normal. 1.1× squeezes maximum hours out of the lamp at the cost of less reaction time when output drifts; 1.3× gives 2–3 weeks of buffer to order, ship, and stage a spare. High-mix lines and safety-critical chemistry should sit at the 1.3× end.
  • Can I keep running past rated life? Sometimes — if (and only if) UV Dose Margin still shows headroom over the chemistry minimum at production line speed. Past rated life, output decay accelerates, so radiometer cadence has to tighten (every shift, not every week).
  • Does this work for UV LED arrays? It computes hours, but the assumptions don't fit. LED arrays degrade over 20,000+ hours and the right metric is irradiance drop, not hours. Use the UV Intensity Decay calculator instead for LED replacement planning.

Last reviewed 2026-05-12.