Free tool
CPA, ROAS and ad budget calculator
Find out how much you need to invest to hit your sales target — and, above all, how much you can pay per customer before the numbers stop working.
Does your ad budget add up?
Fill in your own numbers. Everything is editable and no benchmark is hidden.
Revenue from one closed sale, before costs.
What is left after variable costs. It is the ceiling on what you can pay per customer.
Cost per click you pay today, or the planner estimate.
Out of every 100 visits, how many leave their contact details.
Out of every 100 leads, how many sales close. This field is what separates a B2B calculation from an e-commerce one.
How many new sales you want ads to bring per month.
Optional — for recurring revenue
If the customer buys more than once, enter the total value they generate over the relationship. It replaces the ticket when working out how much you can pay per customer.
How the maths works
Target becomes leads, leads become clicks
The sales target is divided by the close rate to find the leads, and the leads by the page conversion to find the clicks.
Clicks become budget
Clicks needed times CPC. That is where the monthly budget comes from — and the projected CPL and CPA.
Margin sets the ceiling
The most you can pay per customer is the contribution margin of the sale. Above that, every new sale destroys value.
The numbers may not work
When projected CPA passes the ceiling, the tool says so and points at the bottleneck instead of returning a flattering number.
The formula, exactly as it is in the code
leads needed = sales target ÷ lead→sale conv. clicks needed = leads needed ÷ visit→lead conv. budget/month = clicks needed × CPC projected CPL = CPC ÷ visit→lead conv. projected CPA = projected CPL ÷ lead→sale conv. value per customer = (LTV if given, else ticket) × margin break-even CPA = value per customer break-even CPL = break-even CPA × lead→sale conv. projected ROAS = (sales target × ticket) ÷ budget/month break-even ROAS = 1 ÷ contribution margin
No seasonality, no learning period and no auction volatility. Real CPC moves with competition and ad quality — change the field and watch the effect.
Frequently asked questions
CPL is cost per lead: what you pay for someone to leave their details. CPA is cost per closed sale. In B2B the two differ a lot, because not every lead becomes a customer — which is why the calculator asks for both rates.
Because the ticket still contains the cost of delivering the sale. What is left to pay for acquisition is the contribution margin. Using the ticket as the ceiling makes a campaign look viable while it burns cash.
Start with what sales estimates and treat it as an assumption, not a fact. Run a pessimistic and an optimistic value: if the campaign only works in the optimistic one, you have mapped the risk.
It is the minimum ROAS below which the campaign loses money, and it equals 1 divided by the margin. With a 32% margin, any ROAS below 3.1x is burning money even though it looks positive.
No. The maths runs in your browser and nothing is sent to us. The address keeps the assumptions only so you can share the simulation.
Related articles
Posts from our blog on this topic, so you can dig deeper before deciding.
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Want to test these assumptions with people who manage budget daily?
The maths above is the start. What changes the result is tracking to the close, not just to the lead.