How much ad cost per order can you afford?
You can spend at most what an order leaves before advertising – for a €49.90 product with typical costs that is €17.68 per order. If you also want to keep a 15 % margin, the limit drops to €11.89. Everything above is paid out of your own pocket.
Enter your price, costs and campaign numbers – the ROAS calculator shows your limit per order and your real ad cost.
Open the ROAS calculatorThe idea in one sentence
Every order leaves some money after product cost, shipping, fees and returns. That amount is your ad budget per order: spend all of it and you break even, spend less and you keep the rest as profit. Ad platforms call the ad cost per order CPA (cost per acquisition).
| Max. ad cost per order (break-even) | contribution per order before advertising |
|---|---|
| Ad cost per order for target margin m | contribution before advertising − m × net revenue |
| Your real ad cost per order | ad spend ÷ orders from ads (= revenue per order ÷ ROAS) |
How much is left for ads at different target margins
The same €49.90 product. The higher the margin you want to keep, the less you can pay per order – and the higher the ROAS your campaigns must reach:
| Margin you keep | Max. ad cost per order | ROAS needed |
|---|---|---|
| 0% | €17.68 | 2.82 |
| 5% | €15.75 | 3.17 |
| 10% | €13.82 | 3.61 |
| 15% | €11.89 | 4.20 |
| 20% | €9.96 | 5.01 |
What to do when ads eat your profit – step by step
If your real ad cost per order is close to or above the limit, work through these steps in this order:
- Calculate your limit per product, not for the whole shop. Cheap products with a small margin often cannot pay for ads at all.
- Compare the limit with your real ad cost per order from the last 30 days: ad spend divided by the orders the ads brought.
- Pause or lower bids for the products and campaigns that are above the limit. Keep the ones that are clearly below.
- Set the target ROAS in your ad account to the value for your target margin, not to the break-even value.
- If ads are needed but too expensive, work on the order instead: a slightly higher price or lower shipping cost raises the limit.
Before Black Week: check your limit before you raise ad budgets
In November many shops raise their ad budgets and give a discount at the same time. Both work against you: the discount lowers what an order leaves, so the limit for ads drops – and the ROAS your campaigns need goes up. Vendor studies also report higher click prices and a lower ROAS for Google Shopping in Europe in 2026 than a year earlier (vendor data, method not checked – see sources).
The same €49.90 product with a Black Week discount (no target margin, break-even values):
| Discount | Price | Max. ad cost per order | ROAS needed to break even |
|---|---|---|---|
| 0% | €49.90 | €17.68 | 2.82 |
| 10% | €44.91 | €13.92 | 3.23 |
| 20% | €39.92 | €10.16 | 3.93 |
Three checks before you raise the budget
Do these checks per product and campaign before Black Week starts:
- Calculate the limit with the discounted price, not the regular one.
- Compare it with your real ROAS of the last weeks. Raise the budget only for campaigns that stay clearly above the new break-even ROAS.
- Lower your target ROAS in the ad account only if your numbers allow it – a higher budget at a ROAS below break-even only makes the loss bigger.
Worked examples: Product for €49.90, campaign with ROAS 4.0
Example values from the ROAS calculator: price €49.90 incl. 19 % VAT, purchase price €15.00, shipping €4.90, payment fee 2 % + €0.30, 8 % returns. The campaign spent €1,000.00 and reported €4,000.00 revenue.
- Max. ad cost per order (break-even)
- €17.68
- Max. ad cost per order for 15 % margin
- €11.89
- Real ad cost per order of the campaign
- €12.48
- Profit per order after ads
- €5.21
- Margin after ads
- 13.5%
A ROAS of 4.0 sounds good, and the campaign does earn money. But at €12.48 per order it costs more than the €11.89 that would keep a 15 % margin – so the margin drops to 13.5%.