TOP OF FUNNEL
CPM to ROAS funnel calculator
Before you spend a dollar, project what a cold-audience CPM campaign has to do at each funnel stage — click-through, then conversion — to land at a workable ROAS.
Funnel assumptions
Projection
The formula behind this calculator
Working from 1,000 impressions at a given CPM: clicks are impressions × CTR, conversions are clicks × conversion rate, and revenue is conversions × AOV. Dividing revenue by the CPM cost gives:
ROAS = (AOV × CTR% × CR%) ÷ (10 × CPM)
The constant of 10 falls out of converting CPM's per-1,000 basis into percentage points: 1,000 impressions × a CTR expressed as a whole percentage × a conversion rate expressed as a whole percentage, divided by 100 twice, leaves a factor of 1,000/100/10 = 1 embedded in the /10. Enter CTR and conversion rate as ordinary percentages (1.2 for 1.2%, not 0.012) and the formula holds.
Why top-of-funnel math looks different from retargeting
CPM campaigns targeting cold, unqualified audiences live or die on the multiplication of two conversion steps — click-through and landing-page conversion — each of which is usually far lower than what you'd see retargeting warm traffic. A funnel that looks fine at each individual stage (a "good" 1.5% CTR, a "good" 2% conversion rate) can still produce an unworkable CPA once both are compounded against a real CPM.
Use this calculator before launch to stress-test assumptions: hold AOV and CPM fixed at your real numbers, then see how much CTR or conversion rate would need to improve to hit a target CPA, rather than discovering the gap after a week of live spend.
Frequently asked questions
Where do I find my typical CPM for a new cold audience?
Check Ads Manager's delivery estimates for a similar audience size and placement mix, or use recent campaign history from a comparable cold-audience test as a starting assumption.
Is Expected CPA the same as Max Allowable CPA?
No. Expected CPA here is a forward projection of what your funnel assumptions imply you'll actually pay per acquisition — compare it against the max allowable CPA from the TikTok break-even calculator (or your own margin math) to see whether the projected funnel is profitable.
Should I use blended CTR across all placements?
For a first pass, yes. For a more precise projection, run this calculator separately for each placement (feed, stories, in-stream) since CTR and conversion rate both vary meaningfully by placement.