Meta ads calculator

1. Your two numbers

Everything below depends on these. A ROAS figure without your margin is not information.

Break-even ROAS

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Most you can pay per customer

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ROAS = 1 / margin
CPA = AOV × margin

Break-even ROAS is 1 / margin. Below it every extra sale loses money, so it is the only number your results should be compared against.

2. The smallest budget that learns

Meta needs roughly 50 optimisation events per ad set per week to leave the learning phase. Below that, your data cannot tell you whether the campaign works.

Weekly budget, one ad set

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Daily budget, one ad set

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weekly = 50 × cost per event
daily  = weekly / 7

This is a floor, not a target. If it is more than you can lose for three weeks, the budget is not the problem — the funnel is not ready for paid traffic.

3. What a budget is likely to buy

The same chain every forecast uses. Take the pessimistic end of each input if you want the answer to be honest rather than encouraging.

Impressions

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Link clicks

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Purchases

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Revenue

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ROAS

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Verdict: —

At this budget the campaign produces fewer than 50 purchases a week, so it will not leave the learning phase on purchases. Optimise for a cheaper event, such as add-to-cart, and switch later.

impressions = budget / CPM × 1000
clicks      = impressions × CTR
purchases   = clicks × conversion rate
revenue     = purchases × AOV
ROAS        = revenue / budget

A forecast does not predict what will happen. It tells you whether what you are hoping for is arithmetically possible, which is the more useful question.