Find the ROAS your margin can support

Start with product economics

A 50 product with 20 variable cost has 30 contribution before advertising. Dividing 50 by 30 gives a break-even ROAS of approximately 1.67×. At this ratio, contribution pays for ads but leaves nothing for fixed overhead.

Understand the cost of overhead

The simple ROAS threshold excludes rent, salaries and software that do not scale directly per order. Use the reverse planner when you need to cover fixed costs and hit a profit target as well.

Be skeptical of attribution

An ad platform may claim credit for purchases that would have happened anyway. Attributed ROAS is not an incrementality experiment. Compare attribution windows, account for returns, and use consistent revenue definitions.

Do not hide losses behind future value

Repeat purchases may change your economics, but do not assume future revenue without evidence. This calculator uses the immediate contribution per sale. Build a separate retention model before relying on future customer value.

Follow one campaign through to its result

Assume 100 sales at 50 each, variable costs of 20 per sale and advertising spend of 2,000. Attributed revenue is 5,000, giving 2.5× ROAS. Contribution before ads is 3,000; after ads it is 1,000. If this period also has 1,200 fixed overhead, the business records a 200 operating loss under these assumptions.

This is why a positive-looking advertising ratio does not settle the profit question. Keep the campaign calculation and the full operating result visible together, especially when deciding whether to increase a budget.

Derive your own threshold

Break-even ROAS before fixed overhead = price / (price − variable cost), equivalently 1 / contribution margin ratio. At a 60% contribution margin, the threshold is 1 / 0.60 = 1.666…. Reporting 1.67× is a rounded display, not a different underlying formula.

If contribution margin falls to 40%, the threshold rises to 2.5×. If variable costs equal or exceed selling price, there is no positive advertising budget that immediate contribution can support. Improving reported attribution will not fix negative unit economics.

Connect cost per click with conversion

If every visit is paid, cost per acquired sale is CPC / conversion rate. With CPC of 0.40 and conversion of 2%, acquisition costs 20 per sale. A 30 pre-ad contribution leaves 10 per sale before overhead.

A rise in CPC to 0.60 consumes the entire 30 contribution at the same conversion rate. Use the reverse planner for a mix of paid and organic visits. Keep the distinction between a click and a measured visitor explicit if reporting systems count them differently.

Review refunds and attribution before scaling

Choose a reporting window long enough to observe the returns relevant to your offer. If attributed revenue includes purchases later refunded, an early ROAS figure can overstate the amount retained. Avoid adding platform-reported revenue across channels when both may claim the same purchase.

For the next review, collect spend, retained attributed sales, actual variable costs and separately stated overhead. Run a lower-conversion case before increasing spend. A campaign can become less efficient as its audience expands; the historical ratio is not a guarantee for the next budget level.

Try the numbers yourself

Continue reading