Blended ROAS is total revenue divided by total ad spend across all channels combined — a single, top-level view of advertising efficiency. Unlike platform-reported or per-channel ROAS, it needs no attribution: it just compares all revenue to all spend. That makes it simple and hard to game, but it also can't tell you which channels produced the return.
How to calculate blended ROAS.
Total Revenue ÷ Total Ad Spend (All Channels)
Be explicit about what "total revenue" means — new revenue in the period, all revenue, or attributed revenue — and keep it consistent. The defining feature is that blended ROAS is top-down: it doesn't assign credit to any channel, so no attribution model can inflate or distort it. That's its strength and its weakness — it's honest, but directionless.
- Platform-reported ROASPlatform-specific claims. Summed together, they often double-count conversions.
- Blended ROASOverall ceiling. Simple calculation comparing total actual revenue against total spend.
- Attributed ROASAllocated credit per channel, reconciled to match the blended ceiling.
Blended ROAS example.
- Total revenue
- —
- $50,000
- Total ad spend (all channels)
- —
- $12,500
- Blended ROAS
- $50,000 ÷ $12,500
- 4x (400%)
Now compare: if Meta, Google and your other platforms each claim their own ROAS and you sum them, the total often implies far more revenue than the $50,000 you actually earned — because each platform counts the same conversions. Blended ROAS is the reality check that number can't exceed.
Why blended ROAS matters for attribution.
Blended ROAS and attributed ROAS do different jobs, and you need both. Blended is the honest ceiling — because ad platforms over-claim (their summed ROAS routinely exceeds real results), blended ROAS keeps everyone grounded in what actually happened. But it's directionless: you can't decide where to spend from a single blended number.
Attributed, per-channel ROAS is how you allocate — and the test of good attribution is that your channel ROAS reconciles back to blended. Signal Sparrow ties attribution to real Stripe revenue and reconciles it, so attributed and direct/unknown revenue sum to your actual total — no channel ROAS that quietly adds up to more revenue than you earned. Blended tells you the truth; reconciled attribution tells you where it came from. (Pipeline health →)
