What ROAS is break-even? Calculate break-even ROAS and your maximum ad spend per order

Break-even ROAS (BEROAS) is the return on ad spend at which an ad-driven order pays for its own advertising and nothing more. Above it, the ad adds profit. Below it, the ad is buying revenue at a loss.

It is fixed by the economics of the product, not by the campaign. Two shops selling the same item at the same price with the same costs have the same break-even ROAS whether one spends 500 baht a day and the other spends 50,000.

The formula, derived

Contribution margin per order
  CM = price − COGS − platform fee − seller-funded voucher − seller-funded shipping

Contribution-margin ratio
  m  = CM ÷ price

An ad brings in R baht of incremental revenue for A baht of ad spend.
Incremental profit is therefore

  profit = m × R − A

Break-even is where that profit is zero:

  m × R − A = 0
  m × R     = A
  R ÷ A     = 1 ÷ m

and since ROAS = R ÷ A,

  BEROAS = 1 ÷ m

Why ad spend must not be in the formula

A formula circulating on Thai calculator sites defines break-even ROAS as price ÷ (profit before ads + ad cost). Put ad cost in the denominator and the break-even moves every time you change your budget: spend more, and the threshold you are measuring yourself against drops. A constraint that relaxes whenever you violate it is not a constraint.

Break-even ROAS answers "what does one baht of ad spend have to bring back?". The answer depends on how much of a baht of revenue you keep — the contribution-margin ratio — and on nothing else.

A women’s-clothing order on a Shopee Thailand non-Mall shop, priced at 590 baht, on the commission schedule effective 4 August 2026 (17.12%, VAT-inclusive).

• Contribution-margin ratio: 208.99 ÷ 590 = 35.42%.
• Break-even ROAS: 1 ÷ 0.3542 = 2.82. Below 2.82 the ads lose money.
• Maximum ad spend on an order the ad genuinely caused: 208.99 baht. That is the number a bid cap has to respect.
• To keep a 10% net margin: 1 ÷ (0.3542 − 0.10) = 3.93.
• At 60% incrementality the platform dashboard has to show 4.71 — break-even ROAS divided by incrementality — before the campaign is genuinely at break-even, and the ceiling per attributed order falls to 125.40 baht.

Every marketplace ad platform reports ROAS as attributed revenue ÷ ad spend, and counts a sale as attributed when the buyer saw or clicked the ad inside the attribution window. Some of those buyers were going to buy anyway: they searched your brand, they came back to a cart, they were already mid-purchase. The ad was present at the sale, not the cause of it.

Incrementality is the share of attributed sales the ad actually caused. If it is 60%, then a reported ROAS of 5 is an incremental ROAS of 3, and the break-even you have to clear on the dashboard is 1 ÷ (margin ratio × incrementality), not 1 ÷ margin ratio.

Nobody can read incrementality off a dashboard — it is measured by holding out traffic and comparing. Until you run that test, treat the slider as a stress test: if the campaign only clears break-even at 100% incrementality, it is not a campaign you should be defending.

Where a target ROAS should come from

Break-even is a floor, not a goal. To keep a net margin of t on ad-driven revenue, the ad can consume at most (m − t) of every baht:

Target ROAS = 1 ÷ (contribution-margin ratio − net margin you want to keep)

Advice to "run at break-even ROAS × 1.25" appears on several Thai calculator pages with no derivation attached. A multiplier is only meaningful if it comes from a margin you actually want to keep — at a 35% contribution margin, ×1.25 leaves 7 points of net margin, and at a 12% contribution margin it leaves 2.4. The same multiplier does two completely different things.

• It works per order, not per campaign. A campaign spanning several SKUs has a blended contribution margin, and the blend moves with the mix.
• It assumes returns are already priced into COGS. If your return rate is material, raise COGS by the expected return cost rather than editing the fee rate.
• It cannot measure your incrementality. The slider is an assumption you supply, not an estimate we produce.
• Fee rates change. The tables above carry their effective dates; check them against your own income statement before betting a budget on them.

Related reading

• What is contribution margin?
• What is true ROAS?
• Shopee fee structure in 2026
• How to set Target ROAS on GMV Max
• Shopee’s 4 Aug 2026 fee increase, in baht