The price per part falls as quantity rises because set-up is paid once per batch and spread over every part in it, while material and run time per part stay roughly constant. The curve drops steeply at low quantities and flattens as the run cost starts to dominate. It is not always smooth: when a batch outgrows a fixture, a build plate or a shift, a second set-up adds a step, and fixed price tiers add cliffs of their own.
Key points
- Unit cost = set-up ÷ quantity + run cost per part. The first term shrinks; the second does not.
- Most of the fall in unit price happens in the first few dozen parts.
- A second set-up, a second build or a second shift puts a step into the curve.
- Fixed quantity tiers create cliffs where a larger order costs less in total than a smaller one.
- A minimum order value and a separate NRE line keep small and first orders honest.
Where the curve comes from
Every batch has costs that do not depend on how many parts are in it, and costs that do.
| Fixed per batch | Per part |
|---|---|
| CAM programming (if not already done) | Material |
| Machine set-up and tool loading | Machine time per part |
| Fixture mounting | Hands-on labour per part |
| First-article inspection | Consumables and tool wear |
| Subcontractor lot charges | Per-part finishing |
| Paperwork and despatch | Packaging per part |
The set-up cost is divided by the quantity; the rest is not. That one division is the whole shape of a quantity price.
Worked example: unit price from 1 to 500
An example part with €180 of set-up per batch and €6.40 of run cost per part (material, machine time, labour and consumables), priced at a 25% margin. All figures are illustrative.
Worked example: unit price vs quantity, €180 set-up, €6.40 run cost, 25% margin
| Quantity | Set-up per part | Unit cost | Unit price (÷ 0.75) | Batch total | Set-up share of cost |
|---|---|---|---|---|---|
| 1 | €180.00 | €186.40 | €248.53 | €248.53 | 97% |
| 5 | €36.00 | €42.40 | €56.53 | €282.65 | 85% |
| 10 | €18.00 | €24.40 | €32.53 | €325.30 | 74% |
| 25 | €7.20 | €13.60 | €18.13 | €453.25 | 53% |
| 50 | €3.60 | €10.00 | €13.33 | €666.50 | 36% |
| 100 | €1.80 | €8.20 | €10.93 | €1,093.00 | 22% |
| 250 | €0.72 | €7.12 | €9.49 | €2,372.50 | 10% |
| 500 | €0.36 | €6.76 | €9.01 | €4,505.00 | 5% |
Read the table in two halves. From 1 to 50 parts the unit price falls from €248.53 to €13.33, a factor of almost 19. From 50 to 500 it falls from €13.33 to €9.01, about a third. Beyond a few hundred, the price approaches the floor set by the run cost: €6.40 ÷ 0.75 = €8.53 per part, which no quantity will go below.
This is also why a buyer who asks for “a price for 1, 10 and 100” is really asking how much of your set-up they are paying for. Showing the set-up as its own line, or at least showing all three prices together, answers the question before it is asked.
When the curve has steps
The smooth formula assumes one set-up covers any quantity. In practice it does not.
- Fixture or plate capacity. A fixture that holds eight parts, an SLS build that fits forty, a print plate that fits twelve: every extra load is a partial repeat of set-up and handling. In powder-bed printing, cost depends on the build share each part takes, and SLS pricing and nesting shows how that changes the curve.
- Tool life. A long run in a hard material may need a tool change and a re-check partway through.
- Shift length. A batch that runs past the end of a shift may be split and set up twice.
- Material lots. A quantity that needs a second bar length or a second sheet adds offcut waste.
Continue the example: suppose 300 parts no longer fit in one run and need a second set-up. The cost becomes €360 ÷ 300 + €6.40 = €7.60, and the unit price €7.60 ÷ 0.75 = €10.13, which is more than the €9.49 at 250. A formula that knows about the second set-up quotes this correctly; a smooth curve or a fixed tier will not.
The trouble with fixed quantity breaks
A quantity break is a tier on a price list: one unit price from 50 to 99, a lower one from 100. Using the example’s prices at the bottom of each tier:
| Order | Tier unit price | Total |
|---|---|---|
| 99 parts | €13.33 (50-99 tier) | €1,319.67 |
| 100 parts | €10.93 (100+ tier) | €1,093.00 |
The buyer who orders 100 pays €226.67 less for one more part. Any sensible buyer orders 100, and you lose the difference on every order that lands near the top of a tier. Three fixes, in order of preference:
- Price by formula, spreading set-up over the actual quantity. No tiers, no cliffs.
- Use more, closer tiers if the price list must be printed.
- Cap the total: charge the lesser of the tier price and the next tier’s minimum total.
Material breaks are a second curve
Material has its own quantity curve. A stockist may sell a full bar, a full sheet or a full drum cheaper per kilogram than a cut length, and powders and resins are often cheaper by the larger container. Two things follow. First, the material cost per part can fall at the quantity where you switch from cut lengths to full bars, which adds a small step down to the curve. Second, a small order may force you to buy a full bar or container and keep the rest. Price the material you buy for the job, then decide deliberately whether the remainder is stock you will use or waste the job should carry.
Showing quantity prices to the buyer
A buyer who sees only the price for the quantity they typed cannot see where the curve flattens. Showing a short price-break table next to the quote, with the unit price and the total at a few quantities around the requested one, lets them decide for themselves whether 40 is a better buy than 25. It also answers the inevitable “what if we ordered more?” before it becomes an e-mail.
Choose the quantities shown from the shape of your curve, not round numbers alone: show the points where the unit price changes meaningfully, and stop where it no longer does.
Small orders, first orders and reorders
At quantity 1 the set-up is nearly the whole price. A minimum order value guarantees every order covers at least the fixed costs of handling it, whatever its parts cost.
First orders often include work that will not be repeated: designing a fixture, writing and proving a program, a first-article inspection report. Showing that as NRE, separate from the batch set-up, tells the buyer the second order will be cheaper and stops the first order looking overpriced.
Reorders usually save the NRE but not the machine set-up, unless the job is still loaded. A reorder of the same part at a smaller quantity than the first order is the case to watch: the buyer remembers the old unit price, but the set-up is now spread over fewer parts, so the honest unit price is higher. Quoting from the same formula every time, and showing the set-up line, makes that easy to explain. Blanket orders with scheduled releases are the hardest case: each release may need its own set-up, so either price each release as a batch or make the whole quantity at once and agree who pays for storing it.
Discounts vs arithmetic
A “volume discount” taken as a flat percentage off the single-part price ignores where the saving comes from. The set-up spread is a real saving and belongs in the price; a percentage on top comes straight out of margin, as margin vs markup shows. Quick delivery pulls the other way: lead-time pricing covers how rush orders interact with batching. And the full cost build-up behind the run cost is in how to quote a manufactured part.
Quotometry spreads set-up per batch with a parts-per-batch limit, so a quantity that needs a second batch carries a second set-up, and it guards the total so that more parts never cost less in total. The pricing engine page describes the order of those steps.
Questions people ask
Why are small quantities so expensive per part?
Because set-up is paid once per batch, whatever the quantity. Programming, fixturing, loading tools and inspecting the first part might cost the same for one part as for five hundred. Spread over one part it is the whole price; spread over five hundred it is a few cents each. The material and run time per part barely change.
Should I use quantity breaks or a formula?
A formula that spreads set-up over the actual quantity gives a smooth price for every quantity and no cliffs. Fixed quantity breaks are easier to print on a price list but create jumps where ordering more costs less in total. If you use breaks, check the total price at the top of each tier against the bottom of the next.
Do repeat orders deserve a lower price?
Often, because some one-off costs are not repeated. A program that is already written and proven, a fixture that is already made and a first-article report that already exists all save time on a reorder. The machine set-up itself usually happens again unless the job is still on the machine, so a reorder rarely costs nothing to set up.
What is the difference between set-up cost and NRE?
Set-up cost recurs every batch: preparing the machine and proving the first part. Non-recurring engineering is paid once for the life of the part: designing a fixture, writing and proving a program, making a mould. Showing NRE as a separate line lets the buyer see that a second order will be cheaper.
Quotometry prices every part from your own machines and rates, on your website, in seconds.