Max CPA from margin calculator
Estimate the most you could spend to acquire an order while meeting a chosen contribution target.
Last updated
Written by Madly editorial
01 / Your inputs
Run the numbers
Example figures are filled in so you can see a result straight away. Replace them with your own. Results update as you type; no data is sent or saved.
Revenue for one order.
Variable costs attributable to the same order.
Currency to retain after ads, not percentage margin: enter 10 to keep £10 from each order before fixed overhead.
02 / Calculation
Maximum CPA
Calculated result
£26.00
Unit: £/order
Formula
Maximum CPA (£/order) = order revenue (£) − variable costs (£) − desired post-ad contribution (£).
How to read this
If the result is negative, the target cannot be met even with zero ad spend. Revisit costs or the target before scaling.
Assumptions
Treat all inputs as per-order amounts in the same currency. This is a ceiling based on your inputs, not a suggested bid; fixed costs and future orders are excluded.
How to use this tool
- Enter your average order value and your contribution margin percentage.
- Optionally enter the profit you want to keep per order.
- Read the most you can pay per purchase.
- Set alerts or rules in your ad account relative to this number, and review them when price or costs change.
Worked example
Illustrative example: £80 revenue − £32 variable costs − £18 desired contribution leaves £30 for acquisition.
What this measures
Start with order revenue, subtract variable costs, then reserve any contribution you need to keep.
Formula and units
Maximum CPA (£/order) = order revenue (£) − variable costs (£) − desired post-ad contribution (£).
Assumptions and review notes
Treat all inputs as per-order amounts in the same currency. This is a ceiling based on your inputs, not a suggested bid; fixed costs and future orders are excluded.
If the result is negative, the target cannot be met even with zero ad spend. Revisit costs or the target before scaling.
A good max CPA is one you can defend with arithmetic. It is a ceiling set by your margin, not a performance target. Customers who come back may justify a higher figure, but only if you have evidence they do. Use first-order margin for a cautious figure and lifetime value for an aggressive one, and say which you used.
- Average order value and its spread.
- Margin after all variable costs.
- Desired profit per order.
- Evidence of repeat purchase.
- Using revenue instead of contribution when computing the ceiling.
- Using lifetime value you have not actually observed.
- Applying one max CPA to products with very different margins.
- Never updating it after price or shipping changes.
A closer look
Common questions.
- What is max CPA?
- It is the highest cost per acquisition you can pay and still meet your profit goal on the order.
- How is it different from target CPA?
- Max CPA is the ceiling. Target CPA is where you aim, usually below that ceiling.
- Should I include lifetime value?
- Only if you have real repeat purchase data. Otherwise the cautious first-order figure is safer.
- Does shipping count?
- Yes. If you pay for shipping, it reduces contribution and so lowers max CPA.
- How often should I recalculate?
- Whenever price, product cost, shipping or return rate changes.