Semiconductor Cleanroom Downtime Loss Calculator

Estimate how much fab downtime erodes cleanroom contribution. Enter the hourly gross margin at stake, the downtime minutes per incident, and the number of major excursions per quarter. Optional fields capture how much output you can claw back with overtime and the scrap penalty incurred during restart, translating incidents into quarterly and annualized cash exposure.

Gross margin generated per cleanroom hour when tools are online.
Average duration from excursion to qualified restart.
Count of major contamination or tool-down events expected in a quarter.
Optional. Defaults to 0%. Enter the share of lost output you can make up through overtime or spare capacity.
Optional. Defaults to 0%. Applies a scrap charge per incident as a percentage of hourly contribution.

Use plant-specific production data and financial assumptions. This calculator provides directional guidance and should be validated against your fab's cost accounting.

Examples

  • $325,000 per hour, 95-minute incidents, 4 per quarter, 40% recovery, 3% scrap ⇒ Quarterly downtime hours: 6.33 • Quarterly gross margin at risk: $2,060,416.67 • Recovered via make-up capacity: $824,166.67 • Net unrecovered loss: $1,236,250.00 • Restart scrap charge: $39,000.00 • Total quarterly impact: $1,275,250.00 • Annualized impact: $5,101,000.00 • Recovery efficiency applied at 40.00%. • Restart scrap modeled at 3.00% per incident.
  • $210,000 per hour, 60-minute incidents, 2 per quarter, no recovery, scrap blank ⇒ Quarterly downtime hours: 2.00 • Quarterly gross margin at risk: $420,000.00 • Recovered via make-up capacity: $0.00 • Net unrecovered loss: $420,000.00 • Restart scrap charge: $0.00 • Total quarterly impact: $420,000.00 • Annualized impact: $1,680,000.00 • No recovery efficiency entered. • No restart scrap cost applied.

FAQ

Can I model multiple tool families?

Yes. Run the calculator per toolset with its own hourly contribution and downtime profile, then sum the quarterly impacts to see fab-wide exposure.

How do I incorporate insurance recoveries?

Subtract expected payouts from the net unrecovered loss to get the insured downside before entering the result into your business case.

Does this cover WIP aging penalties?

Not directly. Add the carrying cost of delayed wafers to the restart scrap percentage to approximate additional write-downs.

What about cascading bottlenecks in downstream assembly?

If assembly also idles, add its hourly contribution to the revenue per hour input so the calculator captures end-to-end gross margin at risk.

Additional Information

  • Throughput contribution combines wafer ASP, line yield, and fixed cost absorption to show the dollars at risk when a bay stops running.
  • Recovery efficiency credits overtime, spare capacity, or cycle-time compression that recaptures some lost output later in the quarter.
  • Restart scrap rate covers wafers ruined during pump-down, seasoning, or contamination purge immediately after downtime.

Related calculators