Rex says
Money math without the spreadsheet headache. Plug in your numbers and I'll show you exactly where the dollars land.
Try a scenario
Click to load — tweak from there.Inputs
Result
Estimated incremental revenue from change
$23,413
Estimated revenue at new spend level
$173,413
Estimated ROAS at new spend level
2.77
Marginal ROAS of next dollar (current level)
1.95
Current implied revenue
$150,000
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How to use this
- 1Enter current monthly spend ($).
- 2Enter current reported roas.
- 3Enter diminishing returns strength (0 = linear, 0.8 = heavily saturated).
- 4Enter proposed spend change (%).
- 5Read your estimated incremental revenue from change on the right — it updates as you type.
- 6Hit Share to keep the scenario or send it to someone.
About this calculator
Full marketing mix modeling requires regression across months of spend and revenue data with adstock and saturation curves fit statistically. This is a lite version for quick directional analysis: it applies a standard diminishing-returns saturation curve to a channel's current spend and marginal response, so you can estimate the revenue impact of increasing or decreasing spend by a given percentage without waiting for a full econometric model. It uses a power-law saturation function calibrated by a 'diminishing returns strength' input you set based on how saturated you believe the channel already is — a low value assumes near-linear returns (early-stage channel with room to grow), a high value assumes heavy saturation (mature channel where more spend barely moves revenue). The output shows current implied revenue, revenue at the proposed new spend level, and the marginal ROAS of the next dollar, which is almost always lower than average ROAS once a channel is saturated. This is a planning heuristic, not a substitute for real MMM or incrementality testing — use it to sanity-check budget reallocation requests and flag channels where 'just spend more' pitches deserve skepticism, then validate meaningful reallocations with a proper geo test.
Worked example
Using the values the calculator loads with:
Inputs
- Current monthly spend: 50000 $
- Current reported ROAS: 3
- Diminishing returns strength (0 = linear, 0.8 = heavily saturated): 0.35
- Proposed spend change: 25 %
Results
- Estimated incremental revenue from change: $23,413
- Estimated revenue at new spend level: $173,413
- Estimated ROAS at new spend level: 2.77
- Marginal ROAS of next dollar (current level): 1.95
- Current implied revenue: $150,000
What each field means
Inputs
- Current monthly spend ($)
- The current monthly spend used in the calculation, measured in $. Starts at 50000 $ so you have a working example on load.
- Current reported ROAS
- The current reported roas used in the calculation. Starts at 3 so you have a working example on load. Accepted range: 0.1–50.
- Diminishing returns strength (0 = linear, 0.8 = heavily saturated)
- The diminishing returns strength (0 = linear, 0.8 = heavily saturated) used in the calculation. Starts at 0.35 so you have a working example on load. Accepted range: 0–0.9.
- Proposed spend change (%)
- The proposed spend change used in the calculation, measured in %. Starts at 25 % so you have a working example on load. Accepted range: -90–300 %.
Results
- Estimated incremental revenue from change
- Returned as a money amount in US dollars and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Estimated revenue at new spend level
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Estimated ROAS at new spend level
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Marginal ROAS of next dollar (current level)
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Current implied revenue
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
How do I pick the saturation strength value?
Look at how spend has trended against results historically. If doubling spend last year roughly doubled revenue, use a low value like 0.1-0.2. If a 50% spend increase barely moved revenue, you're saturated — use 0.5-0.7. Without historical data, 0.3-0.4 is a reasonable moderate default for an established channel.
Why is marginal ROAS always lower than average ROAS here?
Under any diminishing-returns curve, average ROAS blends the highly efficient early dollars with the less efficient recent dollars, while marginal ROAS reflects only the next dollar spent. Once a channel is saturated, marginal ROAS can be well below average ROAS, meaning the next incremental dollar returns much less than the reported blended number suggests.
Is this the same as real marketing mix modeling?
No. Real MMM fits a regression across months or years of actual spend and revenue data per channel, accounts for adstock (carryover effects), seasonality, and cross-channel interactions, and typically requires a data science team or specialized vendor. This calculator applies one assumed curve shape to give a fast directional estimate, not a statistically fit model.
Should I use this to justify cutting a channel's budget?
Use it to flag channels worth testing a cut on, not to make the final call. If the marginal ROAS estimate is well below your target, run an actual holdout or spend-down test in that channel to confirm before permanently reallocating budget, since the saturation assumption here is a judgment call, not measured data.
Accuracy and limitations
- Results are estimates before tax, fees, and inflation unless an input explicitly covers them.
- Rates are treated as fixed for the whole period — variable-rate products will drift from this projection.
- This is educational maths, not financial advice. Check anything contractual with the lender or your accountant.
Related tools
Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). Marketing Mix Modeling Lite Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/marketing-mix-modeling-lite-calculator
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/marketing-mix-modeling-lite-calculator" target="_blank" rel="noopener">Marketing Mix Modeling Lite Calculator — RevenueLab</a> (2026).</p>
Source: [Marketing Mix Modeling Lite Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/marketing-mix-modeling-lite-calculator) (2026).