The product made in small batches is paying for setups nobody costed.
A standard cost sheet spreads setup and changeover across every unit as if every run were the same size. It is not. A product made in runs of fifteen carries the same setup as one made in runs of four hundred, but absorbs it over a fraction of the volume. Average the cost and the low-volume product looks fine. Cost it properly and it is the one bleeding the plant.
Cost and Profitability Consulting · 150+ models since 2010 · TDABC
Setup and changeover are real, recurring costs that a standard sheet smears evenly across volume, so low-volume and frequently-changed products look more profitable than they are. In one illustrative pattern at a precision-components maker, setup consumed about 25 percent of production staff, and on a low-volume line the setup spend exceeded its combined materials and labour. Those products appeared profitable but lost money. TDABC assigns setup and changeover time to the specific runs that caused them, so the true cost of small-batch and high-mix production becomes visible.
Setup is a fixed cost that volume does not even out.
Every run pays for its setup once, whether it makes fifteen units or four hundred. Spread that fixed cost over fifteen and it dominates the unit cost; spread it over four hundred and it all but disappears. A standard sheet ignores the difference entirely: it takes a year of setup spend and smears it across a year of units, so the short, fiddly run is charged the same setup per unit as the long, easy one. The short run looks healthy, and it is the one quietly draining the plant.
In the illustrative precision-components pattern, setup activity absorbed roughly a quarter of production staff, and on the low-volume line the setup spend alone exceeded direct materials and labour combined. The standard sheet reported a profit. The activity model reported a loss. Same plant, same product, opposite truth.
SETUP COST PER UNIT VS RUN SIZE
Illustrative. The same setup, spread over fifteen units or four hundred. On the short run it can exceed materials and labour combined; on the long run it nearly vanishes. The standard sheet reports the average and hides both ends.
Setup enters the equation as a conditional term.
In a time equation, setup and changeover are not a flat overhead percentage. They are conditional terms that fire only when the work actually happens: setup time per run, changeover time only on a product switch, a quality check only on a critical item. Because setup is fixed per run, the cost per unit climbs as the run shrinks, which is exactly the signal a standard rate erases.
Illustrative time equation for a run of fifteen. Setup and changeover are large per unit at small batch sizes; both shrink as the run grows.
The fix is rarely "drop it".
Set a minimum run
A minimum order or run size spreads setup over enough units to pay. The product survives; the loss does not.
Consolidate batches
Fewer, longer runs of the same product cut total setups across the year, the single biggest lever on a high-mix line.
Cut setup time (SMED)
Reduce the setup itself and every short run gets cheaper at once. The conditional term in the model shrinks for the whole portfolio.
Price the complexity
Where the customer needs short runs, a complexity surcharge makes the cost visible and recovers the margin instead of absorbing it.
In the illustrative case, a minimum run size and a meaningful setup reduction lifted gross margin into the mid-30s and operating margin into the high teens, almost entirely through order discipline rather than cost cutting.
Frequently asked questions
- Why do short production runs lose money?
- Setup and changeover are fixed costs per run, so the fewer units they are spread across, the more each unit carries. A standard sheet averages setup across all volume, so a product made in runs of fifteen looks as cheap to set up as one made in runs of four hundred. Once setup is traced to the run that caused it, the low-volume special often turns out to be the one losing money.
- How does TDABC handle setup and changeover?
- As conditional terms in a time equation, not a flat overhead percentage. Setup time is charged per run, changeover only when a changeover happens, and a quality check only when the item is critical. The cost per unit then rises as run size falls, which is exactly what the standard sheet hides.
- What do you do about it without dropping the product?
- Set a minimum run size, consolidate batches, cut setup time with SMED, or add a complexity surcharge in price. In an illustrative case these levers lifted gross margin into the mid-30s and operating margin into the high teens, without losing the customer.
See what your short runs really cost.
The Profit Check takes five minutes and no data upload. It points to where setup and complexity are most likely hiding, and what it is worth to correct.