How do you calculate furnace downtime cost?

Multiply downtime hours by the hourly lost-output cost and the attribution factor, then add the fixed repair cost. Here 100 hr × $45 × 80% = $3,600 captured, plus $250 fixed, for $3,850 total.

What is the per-hour furnace downtime cost?

Divide the total by the downtime hours. In the example, $3,850 ÷ 100 hr = $38.50 per hour, which blends the variable lost output with the amortized fixed repair.

What does the attribution or capture factor do?

It scales the lost output down to the share that actually hit the business. At 80%, a fifth of the theoretical loss was absorbed — by inventory buffers or a parallel furnace — so only $3,600 of variable loss is counted.

Should I use standard cost or margin for the hourly rate?

Use the contribution margin or true lost-output value per hour, not full standard cost. The point is the money the plant would have earned had the furnace kept running, which is usually margin on displaced production.

Why include a fixed repair cost separately?

The reline brick, labor, and rigging happen regardless of how long output is lost, so they're a flat add-on rather than an hourly rate. Separating them lets you see how much of the $3,850 is lost production versus the physical repair.

Planned vs unplanned downtime cost — how do I compare?

Run the calculator twice. A planned reline typically has fewer down hours, a higher attribution offset from staged inventory, and a lower fixed cost than an emergency breakout, and the dollar gap is your business case for proactive maintenance.

Refractories, Furnace Linings & Foundry Consumables calculator

Furnace Downtime Cost Calculator

Furnace Downtime Cost puts a dollar figure on an idle furnace by combining the lost-output value of every down hour with the fixed cost of the repair or reline that caused it. Foundry and steel-shop managers use it to size the true cost of an unplanned refractory failure — not just the brick and labor, but the melting capacity, throughput, and margin that evaporate while the furnace is cold. The attribution factor keeps it honest: when downstream buffers or a parallel furnace absorb some of the loss, you count only the share that genuinely hit output. It matters because a furnace is usually the plant's bottleneck, so a downtime dollar figure is what justifies proactive relines, spare-lining strategies, and the inspection budget that prevents surprise failures.

What this calculator does

Furnace Downtime Cost puts a dollar figure on an idle furnace by combining the lost-output value of every down hour with the fixed cost of the repair or reline that caused it.
Use it when furnace downtime cost in refractories, furnace linings and foundry consumables is being put through a refractories, furnace linings and foundry consumables weighted-cost review.
It multiplies downtime hours by the hourly lost-output cost and an attribution factor, adds the fixed repair cost, and reports total plus per-hour cost.

Formula used

Furnace Downtime Cost cost = quantity × rate × capture factor + fixed cost
Per-unit furnace downtime cost = total cost ÷ quantity

Inputs explained

Furnace downtime hours:
Lost-output cost per downtime hour:
Share of lost output actually attributable:
Fixed reline or repair cost:

How to use the result

Use it after an outage to size the true loss, or before a planned reline to compare scheduled versus emergency scenarios.
The hourly lost-output rate is an estimate of contribution margin at risk — get that wrong and the total is wrong, so validate it against actual lost sales or displaced production, not just standard cost.

Current U.S. benchmarks

The producer price index for steel mill products stands at 348.53 (BLS, May 2026), up 6.7% from a year earlier. Quotes priced off last quarter's material cost miss this move.
Industrial electricity averages 8.66 cents per kWh across the U.S. (EIA, Apr 2026), up 5.5% from a year earlier. Energy-intensive steps carry this directly into unit cost.
The U.S. has 3,569 primary metal manufacturing establishments employing about 354,911 workers (Census County Business Patterns, 2023).

Common questions

How do you calculate furnace downtime cost? Multiply downtime hours by the hourly lost-output cost and the attribution factor, then add the fixed repair cost. Here 100 hr × $45 × 80% = $3,600 captured, plus $250 fixed, for $3,850 total.
What is the per-hour furnace downtime cost? Divide the total by the downtime hours. In the example, $3,850 ÷ 100 hr = $38.50 per hour, which blends the variable lost output with the amortized fixed repair.
What does the attribution or capture factor do? It scales the lost output down to the share that actually hit the business. At 80%, a fifth of the theoretical loss was absorbed — by inventory buffers or a parallel furnace — so only $3,600 of variable loss is counted.
Should I use standard cost or margin for the hourly rate? Use the contribution margin or true lost-output value per hour, not full standard cost. The point is the money the plant would have earned had the furnace kept running, which is usually margin on displaced production.
Why include a fixed repair cost separately? The reline brick, labor, and rigging happen regardless of how long output is lost, so they're a flat add-on rather than an hourly rate. Separating them lets you see how much of the $3,850 is lost production versus the physical repair.

Last reviewed 2026-05-12.