Contribution per order is the number a dropshipping store lives on
Dropshipping has almost no fixed cost and almost no inventory risk, which means the whole business is decided at the level of a single order. Either the order generates more money than it consumes, or it does not — and because you buy every customer with advertising, the margin left after supplier cost and payment fees is your advertising budget. That figure has a name in managerial accounting: contribution margin, the revenue left after every cost that exists only because the order exists.
Split the variable costs into two groups and the model becomes obvious. The first group is unavoidable once a sale happens: the supplier's price for the unit, the supplier's shipping, the card processor's percentage plus its fixed fee, and an allowance for the orders that get refunded or disputed. Subtract those from revenue and you have contribution before advertising — the most you could ever pay to acquire the customer. The second group is the advertising itself. Whatever is left after that is profit.
Everything else follows from those two numbers. Your maximum profitable CPA is exactly the contribution before advertising. Your break-even ROAS is revenue divided by that same figure — nothing more mysterious than the reciprocal of a margin. And your monthly profit is contribution per order times orders, minus the store platform, apps and tools you pay for regardless. A store that knows these three numbers can read an ad account correctly; a store that does not is guessing.
Why break-even ROAS is just an upside-down margin
Write revenue as R. The percentage costs — payment processing at v and the refund allowance at f — scale with R. The dollar costs — supplier product C, supplier shipping S, and the fixed transaction fee k — do not. Contribution before advertising is therefore R(1 − v − f) − C − S − k, and profit is that minus your CPA.
Now define ROAS the way ad platforms do: revenue divided by ad spend. If ad spend equals the contribution before advertising, profit is exactly zero, so the break-even ROAS is R ÷ (contribution before advertising). Divide top and bottom by R and you get a cleaner statement: break-even ROAS is one divided by your contribution margin before advertising. A product with 50% contribution before ads breaks even at 2.0×. One with 25% breaks even at 4.0×. One with 20% needs 5.0×. That single relationship explains why cheap, low-margin products are so hard to sell profitably with paid traffic — the ROAS they need is arithmetically out of reach on most ad platforms.
Two conventions matter here, and getting them wrong is the most common error in the category. First, use blended CPA, not the platform's reported CPA. Meta and Google count conversions they can attribute to themselves; your bank counts orders. Divide total ad spend by total orders and you get a figure that reconciles to your P&L. Second, be consistent about the revenue base. If your ROAS is calculated on revenue including shipping and tax, your break-even ROAS has to be too, or you will compare two different fractions and conclude the wrong thing. The ROAS calculator and the cost per acquisition calculator deal with those definitions in detail.
Notice what the formula does not contain: your store subscription, your apps, your email tool, your own time. Those are fixed costs. They do not change the break-even ROAS of a single order at all — they change how many orders you need. That is why they enter this calculator once, at the monthly level, and why the calculator reports the number of orders a month required to cover them.
Worked example: a $39.95 product with a $12 CPA
You sell a product at $39.95 with free shipping. Your supplier charges $12.50 for the unit and $4.80 to ship it. Your gateway takes 2.9% plus $0.30. You allow 3% of revenue for refunds and disputes. Blended ad spend works out at $12.00 per order, you expect 400 orders in the month, and your platform and apps cost $250 a month.
- Revenue. R = $39.95 + $0.00 = $39.95.
- Payment fee. 2.9% × $39.95 = $1.15855, plus $0.30 = $1.45855.
- Refund allowance. 3% × $39.95 = $1.1985.
- Variable cost before ads. $12.50 + $4.80 + $1.45855 + $1.1985 = $19.95705.
- Contribution before ads. $39.95 − $19.95705 = $19.99295. This is your maximum profitable CPA.
- Break-even ROAS. $39.95 ÷ $19.99295 = 2.00×. Equivalently, contribution before ads is 50.04% of revenue, and 1 ÷ 0.5004 = 2.00.
- Profit per order. $19.99295 − $12.00 = $7.99, a contribution margin of $7.99295 ÷ $39.95 = 20.01%.
- Monthly contribution. $7.99295 × 400 = $3,197.18.
- Monthly net profit. $3,197.18 − $250.00 = $2,947.18.
- Orders to cover fixed costs. $250 ÷ $7.99295 = 31.3, so 32 orders a month pay for the store before any profit begins.
The interesting fact in that list is the gap between 2.00× and reality. Your actual ROAS at a $12 CPA is $39.95 ÷ $12.00 = 3.33×, comfortably above break-even. But the distance is smaller than it looks: CPA rising from $12.00 to $19.99 — a 67% increase, which a single bad creative cycle or a competitive Q4 can produce — takes the product to exactly zero profit without your ROAS ever going negative. That is the sensitivity paid-traffic operators underestimate.
How to read the result: which numbers actually decide the product
Read the break-even ROAS first, because it is a property of the product and the pricing rather than of your marketing skill. If it comes out above about 3×, you are asking your ad account to do something difficult on cold traffic and you should fix the offer — raise the price, find a cheaper supplier, or bundle to lift order value — before you touch the campaigns. If it comes out near 1.5× or lower, you have unusual pricing power and considerably more room to test.
Then compare your actual ROAS to it. The distance between the two is your entire margin for error, and it shrinks in both directions: CPA rises when competition increases, and contribution falls when suppliers raise prices or refunds climb. Operators who run at a small gap discover that a profitable month and a loss month can be the same store with the same product.
Contribution margin as a percent of revenue is the third reading, and the one to compare across products. A dollar figure hides scale — $8 of contribution on a $40 order is a completely different business from $8 on a $200 order. Sustained paid-traffic e-commerce generally wants contribution after ads to stay in double digits as a share of revenue, because everything not in this calculator still has to be paid: your time, customer support, the platform, and eventually tax. Below 10% there is nothing left for any of it.
Finally, check the orders-to-cover-fixed-costs figure against your realistic volume. It tells you where the business turns on. A store with $250 of monthly tooling and $8 of contribution per order needs 32 orders before the first dollar of profit; the same store with $2 of contribution needs 125. Fixed costs do not change your break-even ROAS, but they absolutely change whether the store is viable — the break-even point calculator handles that side properly.
Break-even ROAS and maximum CPA by contribution margin
| Contribution before ads | Break-even ROAS | Max CPA on a $40 order | Max CPA on a $100 order |
|---|---|---|---|
| 15% | 6.67× | $6.00 | $15.00 |
| 20% | 5.00× | $8.00 | $20.00 |
| 25% | 4.00× | $10.00 | $25.00 |
| 30% | 3.33× | $12.00 | $30.00 |
| 35% | 2.86× | $14.00 | $35.00 |
| 40% | 2.50× | $16.00 | $40.00 |
| 50% | 2.00× | $20.00 | $50.00 |
| 60% | 1.67× | $24.00 | $60.00 |
| 70% | 1.43× | $28.00 | $70.00 |
The worked example sits on the 50% row: contribution before ads of $19.99 on $39.95 of revenue is 50.04%, giving a 2.00× break-even ROAS. Read the row that matches your own product and you have its ROAS floor without any further arithmetic.
Break-even ROAS ignores fixed costs on purpose
The break-even ROAS this calculator reports is a contribution break-even: the point at which one more order stops adding money. It deliberately excludes your platform subscription, apps, contractors and your own salary, because those do not scale with the order and including them would make the figure depend on how many orders you happen to sell.
That makes it the right number for a bidding decision and the wrong number for a business decision. Use the break-even ROAS to decide whether to keep a campaign running today; use the monthly net profit and the orders-to-cover-fixed-costs output to decide whether the store is worth running at all.
Mistakes that make a dropshipping margin look better than it is
- Using the ad platform's CPA instead of blended CPA. Attribution windows and view-through conversions credit the platform with orders your bank statement cannot find. Divide total spend by total orders.
- Leaving the refund allowance at zero. Long transit times from overseas suppliers drive cancellations and disputes, and each one costs the whole order plus the processing fee.
- Forgetting the fixed part of the payment fee. A flat $0.30 is 0.75% of a $40 order and 3% of a $10 one — the reason cheap single-item orders rarely work.
- Treating shipping revenue as free money. Processors charge their percentage on it, and if you charge less than your supplier bills, the difference comes straight out of contribution.
- Comparing this month's ROAS against a break-even ROAS calculated on last quarter's supplier price. Recompute the floor whenever a cost changes.
- Counting the platform subscription in the per-order margin. It is fixed, so dividing it by orders makes the margin move with volume and hides what the product actually earns.
- Ignoring returns handling. Dropshipped goods often cannot be economically returned to the supplier, so a refund frequently costs you the unit as well as the money.
- Judging a product on one order. Repeat purchase changes the picture entirely; if customers buy twice, your allowable first-order CPA is higher than this calculator shows.
What this calculator does not model
It prices a single order at a single moment. It does not model repeat purchase, which is the biggest omission for any store with a consumable product — if the average customer buys 2.4 times, your true allowable acquisition cost is the contribution across all those orders, not one. Build that figure with the customer lifetime value calculator and check it against acquisition cost using the LTV to CAC ratio calculator before you conclude that a campaign is unprofitable.
It also excludes sales tax and VAT, which pass through your account without being revenue in most jurisdictions; import duty, which the import duty and customs fee calculator handles; currency conversion charges on supplier payments; multi-item orders where several units share one shipping cost; volume discounts that lower supplier cost as you scale; and income tax on the profit. It assumes every order ships once, arrives once, and either completes or refunds in full.
If you hold your own stock rather than dropshipping, the model changes because inventory ties up cash and carries obsolescence risk — the Amazon FBA profit calculator adds return on inventory investment for exactly that reason, and the landed cost calculator builds the per-unit cost properly from freight, duty and handling. If you sell on a marketplace instead of your own store, the Etsy fee calculator and the eBay fee calculator replace the advertising line with a commission.
Key terms
- Contribution margin
- Revenue minus all variable costs of an order, expressed in dollars or as a percent of revenue. It is what is left to pay fixed costs; profit is whatever remains after those.
- Break-even ROAS
- Revenue divided by contribution before advertising — the return on ad spend at which one more order adds exactly nothing. Equivalently, one divided by the contribution margin before ads.
- Blended CPA
- Total advertising spend in a period divided by every order in that period, including organic and repeat orders. It reconciles to your accounts; platform-reported CPA does not.
- Maximum profitable CPA
- The largest amount you can pay to acquire one order before it stops making money. Numerically identical to contribution before advertising.
- Fixed cost
- A cost that does not change with the number of orders — store subscription, apps, tools, salaries. It sets how many orders you need, not what each order earns.