Marketing Budget Reallocation Simulator
Average ROAS tells you which channel worked. Marginal ROAS tells you where the next dollar should go, and the two often disagree. Enter what each channel spends and returns today and see how a marketing mix model would move the budget.
Meta: $40,000 → $48,000 · marginal ROAS 1.43x → 1.32x
Google Search: $30,000 → $31,600 · marginal ROAS 1.36x → 1.32x
TikTok: $15,000 → $12,900 · marginal ROAS 1.26x → 1.32x
YouTube: $15,000 → $7,500 · marginal ROAS 1.05x → 1.29x
Budget moves toward channels whose next dollar earns most, until those returns even out. Each channel stays between 50% and 200% of today's spend, where its curve can be trusted.
Talk to us about your measurementA $100,000 monthly budget split across Meta ($40,000 at 2.6x), Google Search ($30,000 at 3.4x), TikTok ($15,000 at 1.8x) and YouTube ($15,000 at 1.5x) earns about $255,500 in incremental revenue. Moving money toward Meta and Search until each channel's next dollar returns about the same, near 1.32x, raises that to about $257,300 for the same spend, and shows that YouTube's next dollar returns well under its 1.5x average.
Average versus marginal ROAS
Every channel saturates. The first dollars reach the most likely buyers; later dollars reach people who were less likely to buy or would have bought anyway. A channel can show a strong average ROAS while its next dollar returns far less.
The simulator models each channel as revenue = a × spend^b, calibrated so the curve passes through your current spend and incremental revenue. The exponent b is the saturation setting: lower values flatten faster. Marginal ROAS is b × average ROAS at the current spend.
Where the inputs should come from
Use incremental ROAS, not platform-reported ROAS. Good sources are a recent marketing mix model, a geo holdout or a conversion-lift study. Platform numbers usually overstate return, and they overstate it unevenly between channels, which pushes budget the wrong way.
If you have no measured saturation, start with the defaults: search and retargeting saturate fastest, prospecting video and new channels slowest. Then test the biggest recommended move before rolling it out.
Why the moves are capped
Response curves are only reliable near the spend levels they were estimated from. The simulator keeps every channel between half and double its current spend. Larger moves need a new test, not a bigger spreadsheet.
Frequently asked questions
What is marginal ROAS?
The revenue earned by the next dollar of spend, as opposed to the average across all dollars spent. Budget is best allocated when marginal ROAS is equal across channels.
Is this a marketing mix model?
No. It uses the same diminishing-returns logic an MMM produces, applied to numbers you provide. A real MMM estimates those curves from your own spend and sales history, including seasonality, pricing and carryover.
What saturation should I use for each channel?
Measured curves are best. As a starting point, branded search and retargeting saturate fastest (around 0.4), broad prospecting and video slowest (around 0.7 to 0.8).
Should I cut a channel whose marginal ROAS is below 1?
Not automatically. Below 1 the next dollar loses money on revenue alone, but channels can feed others or build demand that shows up later. Treat it as a strong signal to test a lower spend.
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