Break-even ROAS & target CPA calculator

The break-even ROAS formula

Break-even ROAS is the revenue-to-ad-spend ratio at which you make exactly zero profit. It is not a benchmark you copy from an industry report — it is a function of your own unit economics, and it changes when your COGS, shipping or payment fees change.

The formula is deceptively simple: average order value divided by contribution margin per order. The subtlety is in what counts as contribution margin. It is price minus every variable cost — COGS, shipping, fulfilment, payment processing, marketplace fees — but before advertising and before fixed overhead.

Contribution margin = AOV − COGS − Shipping − (AOV × Fee%) − Other variable

Break-even ROAS = AOV ÷ Contribution margin
Target ROAS     = AOV ÷ (Contribution margin − Target profit per order)
Max CPA        = Contribution margin − Target profit per order

Adjusting the threshold for repeat purchases

The day-one break-even ROAS is the right threshold for a business with no repeat purchases. For a business where customers come back, the correct threshold is lower — because the first order does not have to pay for the acquisition on its own.

The adjustment is straightforward: divide the break-even ROAS by your twelve-month repeat multiplier. If the average customer places 1.35 orders in the first year, your effective break-even ROAS falls by 26%. This is why subscription and consumable businesses can profitably run ROAS figures that would bankrupt a one-off product brand.

• A 1.35x repeat multiplier lowers break-even ROAS from 1.72x to 1.27x in the example above.
• LTV-adjusted thresholds require trusting your retention curve — do not adjust on hope.
• Cash flow still follows day-one economics: you fund ads now and collect repeat revenue later.

Diminishing returns and the profit-maximising spend level

Every ad account has a point where additional spend buys worse returns. Audience saturation, frequency caps and competition for the same impressions all push marginal ROAS down as spend increases. The third tab of the workbook models this explicitly with a decay rate per spend increment.

The practical consequence: the spend level that maximises revenue is almost never the level that maximises profit. The right question is not "how much can I spend?" but "at what spend does the next dollar of ads earn less contribution than it costs?"

Profitable on paper, insolvent in practice

Ad platforms charge daily or weekly. Revenue arrives from the payment processor two to five days later, and inventory must be purchased before any of it. A business with a positive contribution margin can still run out of cash while growing, because growth consumes working capital.

The scaling tab quantifies this: it multiplies the incremental spend by thirty days to estimate the working capital the growth requires, and flags when that exceeds half your current monthly spend. If you cannot fund it, the constraint is financing, not advertising.

• Cash gap = (ad spend + inventory cost) − collections, measured over your payment terms.
• A 30-day buffer on incremental spend is a reasonable planning assumption for most DTC brands.
• Slow-paying channels (marketplaces with 14-day remittance cycles) widen the gap further.

Reading the campaign model: where to cut and where to scale

The second tab breaks a monthly budget across six channel archetypes — brand search, non-brand search, Meta prospecting, Meta retargeting, short-form video and affiliate — each with a typical ROAS profile.

Two patterns show up almost universally. Brand search carries the highest ROAS and the least incremental value, because those customers were already searching for you. Prospecting carries the lowest ROAS and the most incremental value, because those customers did not know you existed. Judging both by the same ROAS threshold leads to starving prospecting and over-funding brand search — a slow path to a shrinking business.