What are diminishing returns in marketing?
Most channels have a point where the next dollar starts working less hard than the last one. Push far enough past it and more spend barely moves results.
It happens because the first dollars reach the people most likely to respond. As spend grows, a channel reaches less responsive audiences, shows the same people more often, and competes for pricier inventory, so each new dollar works a little less hard.
How do response curves show diminishing returns?
A response curve plots results, such as revenue or conversions, against spend in a channel. It usually rises steeply at first, then flattens. Where a channel sits on its curve tells you whether more budget will help.
| Part of the curve | What it means | What to do |
|---|---|---|
| Steep | Each dollar drives strong growth | Room to invest more |
| Bending | Returns are starting to diminish | Watch the marginal return closely |
| Flat | The channel is saturated | Shift budget to channels with room to grow |
What is an example of diminishing returns?
Two channels, one budget
A brand doubles its search budget. Revenue from search rises, but by far less than it did from the first half of the budget, because search was already near saturation.
Its response curves show video still on the steep part of its curve. Moving part of the extra search budget into video produces more total revenue for the same total spend.
Average return vs. marginal return
Diminishing returns are easy to miss because average return can look healthy while the next dollar is barely working.
| Average return | Marginal return | |
|---|---|---|
| What it measures | Total result divided by total spend | The result of the next dollar |
| What it hides | Saturation in the latest spend | Nothing about the total |
| Best used for | Reporting past performance | Deciding where the next dollar goes |
Why do diminishing returns matter for budget planning?
Most teams set budgets by adjusting last year's split. Without seeing where each channel sits on its curve, teams keep adding money to channels that are already saturated.
- Better allocation. Put the next dollar where it will drive the most growth.
- Defensible plans. Show finance why a channel gets more, or less.
- Scenarios before spend. Test a budget shift on the curves before committing money.
How does Alli do this?
Alli by PMG's Scenario Planner models media response by channel, alongside signals from Alli Brand Equity, and shows where each channel's returns start to diminish. Diminishing-return curves show channel saturation, and brand-adjusted ceilings reflect how brand strength changes what a channel can deliver.
Teams compare reallocation scenarios side by side, lock channels they want to hold, and take the winning plan into Alli Media Planner.
Explore Alli Scenario PlannerDiminishing returns FAQ
What is the law of diminishing returns in marketing?
It's the principle that, beyond a certain point, each additional dollar spent in a channel produces less additional result than the one before it.
What is a marketing response curve?
A chart of results, such as revenue, against spend in a channel. It typically rises quickly, then flattens as the channel saturates.
How do you find the point of diminishing returns?
By modeling how results respond to spend over time, usually with marketing mix modeling, and looking at the marginal return of the next dollar rather than the average.
What should you do when a channel hits diminishing returns?
Consider shifting the next dollars to channels that are still on the steep part of their curves, and test the change as a scenario before committing budget.
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