The starting point: the whole cost
A price is built on top of the cost, and the cost of a printed part has six pieces: material, energy, machine-hour, a failure allowance, your finishing time and packaging. We broke each one down in how much does 3D printing cost, so here we start from a finished number.
In the examples below, the part costs $6.00, everything included. Get yours from the cost calculator and follow along. The examples are in US dollars; in euros the method is exactly the same: swap the symbol and use the fees your channel charges in your country.
Markup is not margin
The most expensive pricing mistake is treating the two words as synonyms:
- Markup is how much you add to the cost. A $6 cost with a 100% markup becomes a $12 price.
- Margin is how much is left of the price, after the channel, the shipping and the tax have taken their share.
Markup is easy to apply and knows nothing about the channel. Look at what it does to a cheap part sold on Etsy with free shipping, using the US reference fees (6.5% transaction fee, 3% + $0.25 payment processing, $0.20 listing fee) and a $5.00 shipping label as a round example. Real label prices depend on weight, size and destination, and every platform changes its fees from time to time:
| Part with a $4 cost | 100% markup | 20% margin |
|---|---|---|
| Price | $8.00 | $13.49 |
| Transaction fee (6.5%) | $0.52 | $0.88 |
| Payment processing (3% + $0.25) | $0.49 | $0.65 |
| Listing fee | $0.20 | $0.20 |
| Shipping label (on you) | $5.00 | $5.00 |
| Part cost | $4.00 | $4.00 |
| What's left | −$2.21 | $2.76 |
The markup "doubled the cost" and lost $2.21 on every sale. The shipping label alone took more than half of the price. On cheap parts, what rules the price is the cost you pay per order, not the cost of the part. Abroad, the platforms' fixed fees are small; the big per-order cost is the label, whenever shipping is on you.
The formula that does the math backwards
Instead of starting from the cost and hoping, start from the margin you want and let the math find the price:
price = (cost + fixed fees + shipping you pay) ÷ (1 − commission − tax on the sale − desired margin)
Everything that is an amount of money goes on top. Everything that is a percentage of the price goes on the bottom. On Etsy, the percentages add up to 9.5% (6.5% + 3%) and the fixed amounts to $0.45 ($0.25 + $0.20). With the $6.00 part and a 20% margin, no shipping and no tax for now:
- On top: 6.00 + 0.45 = $6.45
- On the bottom: 1 − 0.095 − 0.20 = 0.705
- Price: 6.45 ÷ 0.705 = $9.15. List it at $9.25.
Checking: at $9.25 the transaction fee is $0.60, payment processing $0.53, the listing fee $0.20 and the cost $6.00. That leaves $1.92, or 20.8% of the price. The margin you asked for arrived in full. (The same formula gave the $13.49 in the table above: (4.00 + 5.00 + 0.45) ÷ 0.705 = $13.40, rounded up to $13.49.)
The break-even price
Take the margin out of the formula and you have the break-even price, the one at which a sale makes neither a profit nor a loss: (6.00 + 0.45) ÷ 0.905 = $7.13. Below that, every new order makes the hole deeper.
It's the first number to know, and it's the one the calculator shows for each channel. When a customer asks for a discount, the break-even tells you how far you can go.
Shipping, tax and the costs that go missing
Shipping
If you advertise free shipping, or the platform nudges you into it (Etsy, for instance, gives search priority in the US to listings that ship free on orders of $35 or more; check the current rule), the label goes on top of the formula. For a kit with a $15 cost, an $8.00 label on you (a hypothetical amount), Etsy fees and a 20% margin: (15 + 8 + 0.45) ÷ 0.705 = $33.26. List it at $33.50. Shipping depends on weight, size and destination: get a quote with the package already packed, not with the loose part. The calculator has a field just for this.
And if the buyer pays shipping separately, it isn't fee-free: Etsy, eBay and Amazon charge their percentage on the shipping the buyer pays too.
Tax
It depends on where you are and how you are registered. In the US, marketplaces such as Etsy, eBay and Amazon collect and remit sales tax for you in most states, so it doesn't come out of your price; on your own store, sales tax is usually added on top of the price where it applies. In the EU and the UK, if you are VAT-registered and your prices include VAT, the VAT is a percentage of the price and goes on the bottom of the formula (with 20% VAT, it's one sixth of a VAT-inclusive price, about 16.7%). Income tax is charged on profit, not on each sale. Suppose a tax that takes 6% of the sale, just for the math: 6.45 ÷ (1 − 0.095 − 0.06 − 0.20) = $10.00. Check with your accountant which number is yours.
The ones nobody remembers
- Paid ads: if you pay to show up (Etsy Ads, eBay Promoted Listings, Amazon Sponsored Products), divide the spend by the sales of the period and treat it as a cost per part. On Etsy, also check the Offsite Ads fee charged on sales that come from Etsy's ads on other sites.
- Coupons and discounts: a 10% coupon comes out of the margin. If you plan to offer one, the margin needs room for it.
- Returns and exchanges: set aside a small slice of the margin for the order that comes back.
Profit per printer hour
The machine-hour in the cost pays for the printer's wear. This is a different number: how much each hour of machine time is earning you. When the queue is full, printer time is your stock.
| Example | Profit per part | Hours | Per hour |
|---|---|---|---|
| Part A, small | $3.00 | 2 h | $1.50 |
| Part B, large | $6.00 | 10 h | $0.60 |
Part B leaves more per sale, but in the same 10 hours the machine makes five A parts and leaves $15.00, as long as there is demand for them. Set your minimum profit per hour and use it as a floor: a long print that falls below it needs a higher price or leaves the catalog.
A full plate helps a lot. Six small parts on the same plate share the heat-up and the plate change, and the profit per hour goes up without touching the price.
Failures: when 10% isn't enough
The calculator's 10% failure rate is an honest start for a tuned profile and a well-behaved part. In three cases, go higher:
- Tall, thin parts or parts with lots of supports: they fail more, and they fail late.
- Long prints: losing the part at hour 10 of 12 costs almost all of it again.
- Custom orders: agree beforehand who pays for the reprint if the measurement the customer gave you is wrong.
To cut failures at the source, prefer files that have already been printed and checked before they reach you. That's what the "farm-tested" seal on STL Prime means.
Only now, look at the competition
The order matters: your math first, the market second. If competitors charge more than you, there's room for a bigger margin or for a competitive price. If they charge less than your break-even, don't join that fight. The ways out are different: build a kit to spread the per-order costs, change channels, adjust the part to use less machine time, or choose another part. Copying the price of someone who didn't do the math is inheriting their loss.
Checklist before you publish the price
Check, in this order
- Does the cost include all six pieces, machine-hour and failures included?
- Did I use the current commission and fixed fees from the platform's seller dashboard?
- Is shipping on me at this price? Did I get a quote with the package packed?
- Is the tax in, the way my accountant told me?
- Is the price above break-even, with room for coupons and returns?
- Does the profit per printer hour beat my floor?
- Does the file's license allow selling the part? (see how to read it)
A good price is the one that still leaves something after everyone has taken their share.
Run the numbers for your part in the cost and fee calculator. With STL Prime files, the free ones included, you can sell the printed part with no unit limit; the details are in the file license.