The Operator Readout:
- • You make $52.23 gross margin per average order before ad spend.
- • Any Meta/TikTok ad purchase acquired above $52.23 CAC loses money.
- • To hit your 20% net margin goal, your blended ad ROAS must stay above 2.41x.
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Take the 2-minute store audit →How to read your break-even ROAS
Break-even ROAS is the return on ad spend where you stop losing money on an order, not where you start making a healthy profit. It sits below the ROAS number your ad platform reports as a target, because that number usually ignores your actual product cost, shipping, and payment fees. This calculator works backward from your real unit economics, not a platform benchmark, so the number it gives you is the one that actually matters to your bank account.
The two numbers worth watching are Max Allowable CAC (the most you can pay to acquire a customer before that order loses money) and Target ROAS(the ROAS you need to hit your chosen net margin, not just to break even). Most stores only ever look at the ROAS number their ad dashboard shows them. That number is vanity ROAS: it is real revenue over real ad spend, but it says nothing about whether the order behind it was profitable once product cost, shipping, and gateway fees are subtracted.
A worked example
Take a store with an $85 average order value, $22 in product cost, $8 in pick, pack and shipping, and standard 2.9% plus $0.30 payment processing. That leaves roughly $52 in contribution margin per order before ad spend. If Meta reports a 1.4x ROAS on a campaign, the effective CAC on that campaign is about $61, which is above the $52 break-even line. The campaign is losing money on every order even though the ROAS number looks respectable on the ads dashboard. The same store, at a 20% target net margin, needs a blended ROAS closer to 2.4x before that spend is actually profitable, not just breaking even.
What to do when the number is bad
If your real break-even ROAS comes out higher than what your campaigns are actually delivering, there are three places to look before touching ad spend at all. First, the unit economics: a $22 product cost on an $85 AOV is a thin margin before any ad spend enters the picture, so check whether pricing or COGS has room to move. Second, the payment stack: gateway fees compound at volume, and a second processor quote is worth getting once monthly volume passes a few thousand orders. Third, and most commonly overlooked, the actual CAC being paid per channel, which most stores read off a blended platform number instead of breaking out by campaign, where the real losses usually hide in one or two underperforming ad sets rather than the account as a whole.
Why the platform's ROAS number misleads you
Meta and TikTok report ROAS as revenue divided by ad spend, full stop. There is no field in either dashboard for your product cost, your shipping cost, or your payment processing fee, because the platform has no way to know them. A 3x ROAS looks identical on the dashboard whether your margin is 70% or 15%, even though one of those campaigns is printing money and the other is barely surviving. The gap between platform ROAS and break-even ROAS is exactly the size of your cost stack, and it is different for every store, every product line, and often every SKU. Treating the platform's number as the real target is the single most common reason a profitable-looking ad account is quietly losing money.
For the full breakdown of how break-even ROAS, contribution margin, and max CAC fit together, seehow to calculate break-even ROAS for ecommerce. To see whether the leak is upstream of ad spend entirely, in your funnel or your conversion rate, run theStore Funnel Health Scorecard. If the leak is subscription or app spend rather than ad spend, theAutomation ROI Calculator works the same math on operational cost instead of ad cost.