Marketing analytics
Blended vs platform ROAS.
Enter the revenue and spend each ad platform reports, plus your actual store revenue. See each platform ROAS, the blended ROAS and the revenue claimed twice.
Blended ROAS = actual store revenue / total ad spend. If platforms together claim $50,000 on $13,000 of spend but the store took $38,000, platforms show 3.85 and blended ROAS is 2.92.
Your numbers
Result
Worked example
Platform 1 reports $30,000 on $8,000 (3.75x) and Platform 2 reports $20,000 on $5,000 (4.0x). Together they claim $50,000 on $13,000, a combined 3.85x. The store actually took $38,000, so blended ROAS = 38,000 / 13,000 = 2.92x. The platforms claim $12,000 more than the store sold, which is 31.6% above actual revenue.
How it works
Platform ROAS = revenue the platform attributes to its ads / that platform's spend. Blended ROAS = actual store revenue / total ad spend across platforms.
Each platform credits itself under its own attribution window, so one order can be claimed by more than one platform. Polar Analytics describes this as both platforms claiming credit for the same sale, and suggests comparing blended ROAS from real store orders with each platform's figure to see your double-counting exposure.
This tool does the arithmetic only. It cannot split a gap between double counting and other causes. A negative gap means the store took more than the platforms claimed, which can happen with organic, email, direct or untracked sales.
Blended ROAS includes sales the ads did not cause, so it is also not the true return on ads. Neither figure shows profit; compare either with your break-even ROAS.
Sources and basis (opened 2026-10-15): Why Your ROAS Is Wrong: The Hidden Gaps in Shopify Attribution - Polar Analytics; MER: Marketing Efficiency Ratio - Polar Analytics. Everything else is arithmetic on your inputs.
Inputs are user-entered figures. Results are planning estimates, not financial advice or a forecast of future performance. Everything runs in your browser. Nothing you type is sent or stored.
FAQ
What is blended ROAS?
Total store revenue divided by total ad spend across all platforms. It uses one revenue figure, so a sale cannot be counted twice.
Why do my platforms add up to more than my sales?
Each platform claims conversions under its own attribution rules, and a customer who saw several ads can be claimed by several platforms.
Which ROAS should I use to make decisions?
Use platform ROAS to compare ads within one platform and blended ROAS to judge whether advertising pays overall. Compare either with break-even ROAS from your margin.
How large is the gap normally?
It varies by store and setup. One vendor says platform ROAS is routinely 2 to 3 times blended, but that is an anecdote, so measure your own gap with this tool.