The essentials
- Five metrics: cost per result by channel (neutral source), marginal return, share of budget by role (capture, creation, retention), time to return, full ROI.
- The method: budget allocated by quarter, 10 to 20% reallocated at each review towards the channels with the best marginal cost, a floor for the long channels (SEO, awareness).
- 2026 benchmarks: a small business spends 3 to 8% of its revenue on marketing; 20 to 30% of the digital budget of an unmanaged small business goes on activity with no measured result.
- The rule: never more than 50% of the budget on a single channel, never less than 15% on the long-effect channels.
A marketing budget is rarely allocated on figures: it repeats the previous year, follows the pressure of an agency or the fashion for a channel. As a result, 20 to 30% of a small business's digital spend goes to activity whose result nobody measures. This article gives the five metrics used to weigh up choices, the quarterly reallocation method and the thresholds to respect. Building the initial budget is covered in building an effective marketing plan, and the link between objectives and metrics in connecting business objectives and marketing KPIs.
The five metrics used to weigh up choices
| Metric | Calculation | Use in the decision |
|---|---|---|
| Cost per result by channel | Full channel spend / qualified leads or sales attributed by a neutral source (GA4, CRM) | Rank the channels |
| Marginal return | Additional results obtained from the last 10% of budget added | Know where one more euro still pays |
| Share of budget by role | Capturing intent / creating demand / retention | Avoid the all-capture approach that plateaus |
| Time to return | Time between the spend and the result (days for Google Ads, months for SEO) | Not judging a long channel on one month |
| Full ROI | (Margin generated minus full cost) / full cost, agency and internal time included | Decide the total budget |
The cost per result reported by the platforms (Google Ads, Meta) is not suited to these decisions: each one claims the conversions according to its own window, and their sum exceeds reality by 30 to 80%. The neutral source is GA4 with data-driven attribution for B2C, the CRM for B2B; see data-driven attribution.
Marginal return, the forgotten metric
A channel with a good average cost can be saturated: the first €1,000 on Google Ads captures the most profitable queries, the next €1,000 broader queries, and the last €1,000 clicks that no longer convert. The average cost stays acceptable, the marginal cost explodes. To measure it, raise a channel's budget by 20% for a month and compare the additional results with the additional cost; the simulation tools in Google Ads and Meta give a first estimate. The rule is simple: move budget from the channels whose marginal cost exceeds the value of a result towards those whose marginal cost stays below that value.
Allocate by role before allocating by channel
| Role | Channels | Share of digital budget (small business, 2026) | Time to return |
|---|---|---|---|
| Capturing intent | Google Ads search, Shopping, transactional SEO, Google Business Profile | 40 to 55% | Weeks (Ads) to months (SEO) |
| Creating demand | Social advertising, video, content, GEO, events | 25 to 40% | 2 to 12 months |
| Retention and conversion | Email, CRM, remarketing, site optimisation | 10 to 20% | Weeks |
| Measurement and steering | Tools, dashboards, testing | 5 to 10% | Immediate |
A company that puts everything into capture plateaus: existing demand is finite, and the cost per click rises with the competition. A company that puts everything into creating demand does not harvest. The balance depends on maturity: an unknown brand starts with capture, an established brand invests more in creation and retention. Budgets by social channel are detailed in the SMA budget and the SMO budget.
The quarterly reallocation method
- Consolidate: for each channel, the full spend (media, agency, tools, internal time), the results from a neutral source, the cost per result, the trend over two quarters.
- Rank: the channels from the best to the worst cost per result, taking the time to return into account (an SEO channel launched three months ago is not judged).
- Reallocate 10 to 20%: take budget away from the saturated channels or those whose marginal cost is too high, and add it to the channels whose marginal return is still good. Never more than 20% per quarter, otherwise the advertising algorithms go back into their learning phase.
- Respect the floors: at least 15% of the budget on the long-effect channels (SEO, content, awareness), even when their cost per result for the quarter looks high.
- Document: every budget movement with the reason and the metric that will make it possible to judge it the following quarter.
The thresholds to respect
- Concentration: never more than 50% of the budget on a single channel; a rise in CPC or a suspended account must not stop the business.
- Maximum cost per result: set from the margin: in B2B, a cost per qualified lead below 10% of the margin on a deal; in e-commerce, a net ROAS above the break-even ROAS. The calculation method is in how to calculate marketing ROI.
- Test budget: 5 to 10% set aside for a new channel or format each quarter, judged against criteria set before the launch.
- Seasonal reserve: 10 to 20% kept for the peaks (sales, trade shows, end of year) rather than spread across the year.
The mistakes that waste the budget
- Repeating last year: costs and channels change; a copied budget keeps the mistakes.
- Deciding on the platforms' figures: every platform proves that it deserves more budget.
- Judging a long channel on one month: SEO, content and awareness are judged over two to four quarters.
- Forgetting the full cost: a “free” channel such as SEO or organic social costs internal time and agency time; without that cost, the comparison is wrong.
- Not capping: multiplying small channels at €200 a month that produce neither learning nor results.
How GreenRed helps
Rather than juggling several tools, GreenRed's return on investment module brings these metrics together in a single dashboard, compares them over time and tells you which actions come first. You can try it free, with no card, from the Pricing.
Frequently asked questions
Which KPIs should you use to allocate a marketing budget?
The cost per result by channel measured in a neutral source (GA4 or CRM), the marginal return of the last budget added, the share of budget by role (capture, demand creation, retention), the time to return of each channel and the full ROI, agency and internal time included.
How often should you reallocate the budget?
Every quarter, moving 10 to 20% of the budget from the saturated channels towards those whose marginal return is still good. More frequent or larger movements restart the learning phase of the advertising platforms and make it impossible to judge the long channels.
What marketing budget for a small business in 2026?
Between 3 and 8% of revenue, 10 to 15% during a launch or a push for growth. Digital represents 55 to 70% of that budget, split 40 to 55% on capturing intent, 25 to 40% on creating demand, 10 to 20% on retention and 5 to 10% on measurement.
Why not decide using the platforms' ROAS?
Because each platform attributes to itself any conversion preceded by a click or a view, and the sum of their conversions exceeds reality by 30 to 80%. The platforms' figures serve to optimise within the tool; choosing between channels requires a neutral source.
How can you protect the long-effect channels?
With a floor: at least 15% of the budget on SEO, content and awareness, judged over two to four quarters and not on the month. Without that floor, quarterly reallocation empties these channels in favour of advertising, and dependence on paid capture increases.