How do you calculate total rework cost?

Multiply units produced by the rework rate to get rework events, multiply by cost per event for variable cost, then add fixed overhead. With 200 units, 5% rework, $85 per event and $600 overhead, variable cost is $850 and total is $1,450.

What is rework cost per good unit?

It is total rework cost divided by the good units actually shipped. Here $1,450 over 190 good units (200 minus 5% reworked) is $7.25 per good unit — the rework burden each shippable piece carries.

What is a good rework rate for HVAC fabrication?

Well-run sheet-metal shops target rework below 2-3%. A 5% rate, as in this example, is a clear signal to investigate leak tests, fit-up and weld quality before the cost compounds across volume.

Why include fixed overhead in rework cost?

A dedicated rework bench, tooling and a portion of supervisory time exist whether or not volume is high. The $600 fixed overhead here is real spend that variable per-event costing alone would miss.

How is rework cost different from scrap cost?

Rework recovers a defective unit by spending labor and material to fix it; scrap writes the unit off entirely. Rework cost is usually lower per unit but adds cycle time and can mask a process that should be fixed upstream.

How can I lower rework cost per good unit?

Cut the rework rate through better fit-up and in-process leak testing, reduce average event cost with standardized repair procedures, or raise throughput so fixed overhead spreads over more good units.

HVAC Ductwork, Air Handling & Mechanical Products calculator

Ductwork and AHU Rework Cost Calculator

Rework Cost quantifies what fixing defective ductwork and air-handling assemblies actually costs a fabrication shop — the variable cost of every rework event plus the fixed overhead of running a rework area. Plant managers and quality engineers use it to put a dollar figure on a rework rate that often hides inside labor variances, and to see the true cost burden each good shipped unit carries. In sheet-metal HVAC work, leak fixes, reseam welds, flange re-fits and coil rework are common, so a few points of rework rate can quietly erode margin on an otherwise profitable line.

What this calculator does

Estimate the total rework cost for ductwork fabrication or air handling unit production. Enter total units produced, rework cost per event, the rework rate, and fixed rework area overhead to calculate total rework exposure and rework cost per good unit.
Use this when reviewing the quality cost of your ductwork fabrication or AHU assembly operation. Rework on ductwork may include re-sealing leaking joints, re-cutting off-size sections, re-rolling seams, re-forming flanges, or re-brazing leaking coil connections. Quantifying the rework cost per good unit helps justify investment in process improvements, better tooling, or operator training.
It computes variable rework cost from units, rework rate and cost per event, adds fixed rework overhead, and divides the total over good units to give cost per good unit.

Formula used

Variable rework cost = units produced × rework rate × cost per event
Total rework cost = variable rework cost + fixed overhead
Rework cost per good unit = total rework cost ÷ (units × (1 - rework rate))

Inputs explained

Duct sections or AHU assemblies produced:
Average rework cost per event:
Rework rate:
Fixed rework area overhead per period:

How to use the result

Use it to cost out a known rework rate, justify a quality investment, or load rework burden into a quote.
It treats every rework event as the same average cost; a single major AHU teardown can cost far more than the average, so high-variance defects need event-level costing rather than a flat per-event figure.

Current U.S. benchmarks

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.
U.S. housing starts run at 1,177k per year (Census, May 2026), down 8.7% from a year earlier, the demand driver for building products.

Common questions

How do you calculate total rework cost? Multiply units produced by the rework rate to get rework events, multiply by cost per event for variable cost, then add fixed overhead. With 200 units, 5% rework, $85 per event and $600 overhead, variable cost is $850 and total is $1,450.
What is rework cost per good unit? It is total rework cost divided by the good units actually shipped. Here $1,450 over 190 good units (200 minus 5% reworked) is $7.25 per good unit — the rework burden each shippable piece carries.
What is a good rework rate for HVAC fabrication? Well-run sheet-metal shops target rework below 2-3%. A 5% rate, as in this example, is a clear signal to investigate leak tests, fit-up and weld quality before the cost compounds across volume.
Why include fixed overhead in rework cost? A dedicated rework bench, tooling and a portion of supervisory time exist whether or not volume is high. The $600 fixed overhead here is real spend that variable per-event costing alone would miss.
How is rework cost different from scrap cost? Rework recovers a defective unit by spending labor and material to fix it; scrap writes the unit off entirely. Rework cost is usually lower per unit but adds cycle time and can mask a process that should be fixed upstream.

Last reviewed 2026-05-12.