How much should an eCommerce brand spend on ads per month?
A practical budget model for brands between €0.5M and €20M: the conversion-volume floor, the percentage-of-revenue band, and how to know when to add budget.
Short answer
Most eCommerce brands spend 8–20% of revenue on ads, but the real floor is set by data, not percentage: each campaign needs roughly 30–50 conversions per week to optimise. In practice that means €1,500–5,000 per month at €0.5M revenue and €25,000–90,000 at €10M.
Key takeaways
- The optimisation floor — 30–50 conversions per week per campaign — decides your minimum viable budget.
- 8–20% of revenue is the normal band; growth-stage brands sit at the top of it, mature brands at the bottom.
- Budget below the floor produces noisy data and slow learning, which looks like bad performance but is bad measurement.
- Add budget when contribution profit per euro is still positive at the current spend level, not when ROAS looks nice.
- Reserve 10–20% of media budget for creative production; it is the single largest performance lever.
The conversion-volume floor comes first
Ad platforms optimise with machine learning, and machine learning needs examples. Meta's own guidance has long pointed at roughly 50 conversions per ad set per week to exit the learning phase; Google's Smart Bidding stabilises around a similar order of magnitude. Below that, the algorithm is guessing, results swing wildly week to week, and every test is inconclusive.
So the first budget question is not 'what can we afford?' but 'what does 30–50 weekly conversions cost at our current CPA?'. At a €35 CPA, one campaign needs roughly €1,050–1,750 per week to stay out of learning. If you cannot fund that, run fewer campaigns rather than under-funding several.
| Target CPA | 30 conv./week | 50 conv./week |
|---|---|---|
| €15 | €1,950/mo | €3,250/mo |
| €25 | €3,250/mo | €5,400/mo |
| €35 | €4,550/mo | €7,600/mo |
| €60 | €7,800/mo | €13,000/mo |
Per campaign, not per account. Consolidate campaigns before adding budget you do not have.
The percentage-of-revenue band
Once you are above the floor, percentage of revenue is a useful sanity check. Brands defending a position spend 6–10%. Brands growing 30–60% a year typically spend 12–20%. Brands launching a category or entering a new market can run 25%+ for a quarter, funded deliberately as customer acquisition investment.
Read the percentage together with repeat-purchase rate. A consumable with a 45% 90-day repeat rate can spend far more on the first order than a one-off purchase, because the second and third orders carry no acquisition cost.
| Annual revenue | Defensive (8%) | Growth (15%) |
|---|---|---|
| €500K | €3,300/mo | €6,250/mo |
| €1M | €6,700/mo | €12,500/mo |
| €5M | €33,000/mo | €62,500/mo |
| €10M | €67,000/mo | €125,000/mo |
| €20M | €133,000/mo | €250,000/mo |
How to decide when to add budget
Add budget in 20–30% increments while contribution profit per additional euro stays positive. Increase faster and you reset the learning phase; increase slower and you leave a quarter of growth on the table.
The stop signal is not a ROAS threshold. It is the point where the last €5,000 of spend generated less contribution profit than it cost. Track that marginal number monthly, and the budget conversation stops being a matter of taste.
- Raise budgets in steps of 20–30%, then hold for 5–7 days
- Watch marginal contribution profit, not headline ROAS
- Never raise budget and change targeting or creative in the same week
- Keep a fixed baseline through seasonal dips so learning is not lost
Budget the creative, not just the media
In an account with clean tracking, creative explains more performance variance than targeting does. Yet most brands allocate 100% of budget to media and expect the agency to source assets from a product folder.
Set aside 10–20% of your media budget for creative: UGC, static variants, hooks and product demonstrations. At Vibe Digital we bundle UGC from native-speaking creators specifically because creative volume, not audience tinkering, is what unlocks the next spend tier.
What under-spending actually costs
A brand running €900 per month across four campaigns has no campaign above the learning threshold. Every result is noise, no test reaches significance, and after six months the conclusion is usually 'paid ads do not work for us'.
The same €900 concentrated into one campaign, with one clean conversion event and three creative variants, produces a readable result inside a month. Concentration beats coverage at every budget below roughly €5,000 per month.
FAQ
What is the minimum realistic ad budget for a small eCommerce brand?
Around €1,500 per month, concentrated in a single channel and a single campaign. Below that, you cannot reach the conversion volume the platforms need to optimise, and results will be dominated by randomness rather than by your decisions.
Should I split budget across Meta, Google and TikTok from the start?
No. Fund one channel above its optimisation floor first, prove unit economics there, then add a second channel with its own dedicated floor. Splitting a small budget three ways guarantees three under-performing channels.
How much of the budget should go to retargeting?
Typically 10–25%. Retargeting is capped by traffic volume — spending more than the audience can absorb simply raises frequency and annoys buyers. Grow the prospecting pool and the retargeting budget grows with it.
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