Prototype vs Low Volume vs Mass Production Cost
The most common quoting mistake a buyer makes is extrapolating from a prototype price. A one-off part and a fifty-thousandth part share a geometry and almost nothing else about their cost structure. This model separates the two so you can see which one you are paying for.
Cost per part falls as quantity rises because a fixed element is divided by a larger number, not because material gets cheaper. The curve drops steeply at first, flattens once unit cost dominates, and then steps down again if tooling becomes worth buying. Three shapes, one calculation.
The model
Total cost = one-off cost + (unit cost × quantity). Unit price = total cost ÷ quantity. That is the whole of it. Everything interesting is in the question of what belongs in the one-off term and what belongs in the unit term.
| Element | One-off | Per unit | Behaviour as quantity rises |
|---|---|---|---|
| Material | — | Scales with mass and nesting utilisation | Flat per unit, small improvement from better nesting |
| Cutting time | — | Scales with cut length and thickness | Flat per unit |
| Programming / nesting | Yes | — | Divides by quantity |
| Machine setup | Yes | — | Divides by quantity |
| Forming time | — | Scales with bend count | Flat per unit |
| Fixture | Yes (if needed) | — | Divides by quantity |
| First article inspection | Yes | — | Divides by quantity |
| Finish batch setup | Yes | — | Divides by quantity |
| Finish area cost | — | Scales with coated area | Flat per unit |
| Stamping die | Yes (if chosen) | — | Divides by quantity, but replaces a higher unit cost |
Shape one: the fixed-cost curve
With unit cost constant, unit price falls as a rectangular hyperbola: steeply while the fixed term still dominates, then flattening toward the asymptote of the unit cost. The practical consequence is that the first quantity band is where the biggest relative savings live. Going from 1 to 10 changes the unit price far more than going from 1,000 to 1,010.
This is why a supplier quoting 1, 10, 100 and 1,000 sees a curve rather than a straight line, and why the gap between the 1 and 10 quotes is usually the largest on the page.
The numbers are deliberately round so the shape is visible rather than the arithmetic. What matters is the ratio between the 1-piece and 10,000-piece unit price — here about 51×, arising entirely from dividing a fixed 1,000 over a larger quantity.
| Quantity | Total | Unit price | Index (1,000 pcs = 1.00) |
|---|---|---|---|
| 1 | 1,020 | 1,020.00 | 26.2× |
| 10 | 1,200 | 120.00 | 3.08× |
| 100 | 3,000 | 30.00 | 0.77× |
| 1,000 | 21,000 | 21.00 | 0.54× |
| 10,000 | 201,000 | 20.10 | 0.52× |
Shape two: where tooling changes the function
A stamping die does not just add a fixed cost; it replaces the unit cost with a lower one. That makes the total-cost function piecewise: below the break-even the laser route is cheaper, above it the tooled route is, and the crossover is where the two lines cross.
Break-even quantity = die cost ÷ (laser unit cost − stamped unit cost). Both unit costs are knowable from a quote on the same part, which is why the useful request to a supplier is "quote this part both ways and tell me where the lines cross" rather than "quote the cheapest way".
| Quantity | Laser total | Stamped total | Cheaper route |
|---|---|---|---|
| 100 | 2,000 | 12,800 | Laser |
| 500 | 10,000 | 16,000 | Laser |
| 1,000 | 20,000 | 20,000 | Break-even |
| 2,000 | 40,000 | 28,000 | Stamped |
| 5,000 | 100,000 | 52,000 | Stamped |
Shape three: where the curve stops being about quantity
Above a certain volume the fixed term is negligible and the unit price is set by material and machine time. At that point, further savings have to come from the design rather than from the order size: less cut length, fewer bends, thinner gauge where it is allowed, better nesting, or a standard colour instead of a matched one.
This is the practical signal to change the conversation. If the quote at 5,000 and the quote at 20,000 differ mainly in the material line, the batch size is no longer the lever — the drawing is.
How to use this on your own part
- Ask for a quote at three or four quantities rather than one, and look at where the curve flattens.
- Ask for the one-off element to be shown separately so you can see whether the reduction is amortisation or a specification change.
- If demand is predictable, test whether one larger order beats two smaller ones — each order carries its own setup.
- Once the curve has flattened, stop shopping on quantity and start reviewing tolerance, bend count and finish.
Frequently asked questions
Why is the per-part price so much higher for a single piece?
Because programming, machine setup, first-article checks and finishing batch preparation do not scale with quantity. At one piece those fixed costs are carried entirely by that piece. Nothing about the part is more expensive; there is simply nothing to divide the fixed element by.
Is the price reduction at higher volume a discount?
Not in the sense of a rate concession. It is arithmetic. We show the one-off element separately so a buyer can see whether a reduction comes from amortisation or from a change in the specification between the two quotes.
At what quantity does tooling become worth it?
Where the die cost equals the per-part saving times the quantity. That crossover is calculated from two quotes on the same part, and the answer moves with the quantity assumption — which is why the volume you are confident about matters more than the exact crossover point.
Can you quote a range rather than a single quantity?
Yes, and it is the more useful form for a decision. A quote at several quantities shows where the curve flattens, which tells you whether batching or redesign is the better lever. A single quantity answers a question nobody asked.
Send the drawing, get a real answer
An engineer reviews your model for manufacturability and returns a costed quotation — with the DFM observations that would change the price.