If your ad budget is based on what feels comfortable, you are probably underinvesting, overspending, or doing both at different times. The real answer to how much should ecommerce brands spend on ads is not a flat percentage or a copied benchmark. It comes down to margin, cash flow, repeat purchase behaviour, and how efficiently your campaigns turn spend into profitable revenue.
That is why blanket advice like “spend 10% of revenue” is too lazy for serious eCommerce businesses. A brand with 75% gross margins, strong retention, and a proven hero product can spend far more aggressively than a low-margin business with weak conversion rates. The number only matters if it works commercially.
How much should ecommerce brands spend on ads? Start with breakeven
Before you set any budget, you need to know your breakeven cost of sale or customer acquisition cost. If you do not know the point at which ad spend stops being profitable, you are budgeting blind.
Start with contribution margin, not just top-line gross margin. That means product cost, shipping, payment fees, platform fees, discounts, and any variable fulfilment costs should already be accounted for. If your average order value is £80 and your true contribution before ad spend is £28, that £28 is the room you have to acquire the sale.
From there, decide whether first-order profitability is required. Some brands need every purchase to be profitable immediately because cash flow is tight. Others can afford to break even or even lose slightly on first purchase because repeat rate and lifetime value justify it. Neither approach is automatically right. What matters is knowing which game you are playing.
Revenue percentage is a starting point, not a strategy
A lot of brands ask what percentage of revenue should go into ads because it sounds neat. In practice, ad spend as a percentage of revenue is a lagging metric. It can help you sense-check your budget, but it should not decide it.
For established eCommerce brands, paid media often lands somewhere between 10% and 25% of revenue. Some efficient brands run lower. Some growth-stage brands push much higher. But this range only means anything when paired with your margins and objectives.
If your blended MER stays healthy at 15% ad spend, you may have room to scale harder. If 12% already crushes your cash flow, spending more will not fix the fundamentals. The right budget is the one your business model can absorb while still creating the outcome you want.
Budget by business stage, not by guesswork
Early traction stage
If a brand is still validating offers, pricing, or conversion rate, large budgets usually create expensive noise. At this stage, the goal is not brute-force scale. It is proving that traffic converts, products resonate, and tracking is reliable.
That often means a modest but meaningful test budget – enough to gather signal, not so little that the platforms cannot learn. For many brands, a few thousand pounds per month is the minimum point where campaign management starts producing usable data. Below that, you are often spreading budget too thinly across channels, audiences, and products.
Established growth stage
Once your store converts consistently, your average order value is stable, and you know your allowable acquisition cost, budget can become more assertive. This is where spend should follow efficiency thresholds. If paid social and Google Shopping are both hitting target, holding budget back simply protects comfort, not profit.
For brands in this stage, it is common to increase spend by 10% to 30% at a time while watching blended performance, not just channel-reported ROAS. Scale should be earned by data, not forced by ambition alone.
Aggressive scale stage
At higher spend levels, efficiency usually softens. That is normal. The question is whether the additional revenue still produces acceptable profit and cash flow. Serious brands understand that the cheapest conversions come first. As you push harder, you buy broader audiences, higher CPMs, and more marginal demand.
This is where disciplined campaign structure matters. If you scale spend without feed quality, creative testing, landing page strength, and waste control, performance slips faster than it should.
The four numbers that should set your ad budget
There are plenty of metrics in ad accounts. Only a handful should really shape budget decisions.
1. Breakeven ROAS or allowable CAC
This is the non-negotiable number. If your target is detached from margin reality, everything else is theatre.
2. Conversion rate
Weak conversion rates make brands blame media when the site is the real issue. If your store converts poorly, spending more simply buys more expensive failure. Budget should reflect website strength as much as ad performance.
3. Average order value
A higher AOV gives you more room to acquire customers. Brands with bundles, upsells, and better merchandising can usually spend more aggressively than brands relying on one low-ticket item.
4. Repeat purchase rate
If customers come back predictably, you can justify a less conservative first-order target. If they do not, your acquisition budget has to be much tighter.
Channel mix changes the answer
Anyone giving you one universal budget number for all paid media is simplifying the wrong thing. Google Ads, Google Shopping, Performance Max, and Meta do different jobs.
Search and Shopping often capture existing intent. They can produce stronger short-term efficiency, particularly for brands with established demand and a clean product feed. Meta is better at demand generation and can be essential for scale, but it often looks weaker if you judge it only on last-click returns.
That means your total budget should not just answer “how much”. It should answer “where, why, and at what return threshold”. A brand spending £20,000 per month with 70% allocated to high-intent traffic will behave very differently from one spending the same amount with most of it on prospecting social campaigns.
The stronger approach is to build budget around role. Capture demand where it already exists. Create demand where there is headroom. Then measure both against blended commercial performance.
The biggest budgeting mistake: spending to the platform, not the business
Ad platforms will always suggest spending more. Agencies sometimes do the same. More budget sounds like growth, but only if the economics hold.
The wrong way to budget is to pick a number first and hope performance catches up. The right way is to identify your profitable thresholds, then push budget until the marginal return becomes unacceptable. That is a very different mindset.
This is also where vanity metrics cause damage. Clicks, impressions, and platform-attributed revenue can make a budget look healthy while the business feels the opposite. If cash is tightening, stock is moving badly, or blended profit is slipping, your budget is too high regardless of what the dashboard says.
A practical way to set your ad budget
Start with the maximum amount you can spend profitably per order or per new customer. Multiply that by realistic order volume targets, not fantasy growth figures. Then pressure-test it against cash flow.
If you want 500 orders per month and your allowable acquisition cost is £18, your rough ceiling is £9,000 in spend to hit that target efficiently. If performance improves through better conversion rate, stronger creative, or feed optimisation, that ceiling rises. If efficiency falls as you scale, the ceiling drops.
Then split budget by channel role and confidence level. Put more spend into what is already converting reliably. Reserve enough for testing so the account does not stagnate. Keep a close eye on stock position and margin by product line, because the right budget for one category may be completely wrong for another.
This is why serious eCommerce PPC management is never just media buying. Budgeting is tied to merchandising, offer strategy, feed quality, landing pages, and retention economics.
When should you increase spend?
You should increase spend when three things are true. First, you are hitting or beating your target efficiency. Second, demand has not been fully saturated. Third, the business can handle the extra volume operationally and financially.
If one of those is missing, scaling gets messy. We see this often with brands trying to force growth while stock, website speed, or conversion rate are still limiting performance. More budget then acts like a magnifying glass on underlying problems.
When should you cut spend?
Cut spend when the economics break, not just when a few days look ugly. Paid media performance fluctuates. That is normal. But if your blended numbers are consistently outside target, or if cash flow no longer supports your acquisition model, budget needs to come down while the causes are fixed.
That does not always mean a full retreat. Sometimes it means shifting spend toward branded search, best-selling products, warmer audiences, or the countries and campaigns with the cleanest margin profile.
For established brands, the better question is rarely “how much can we afford to spend?” It is “how much can we spend profitably, repeatedly, and with confidence?” That answer is rarely neat, but it is always measurable. If your numbers are clear, your budget gets clearer. And if they are not, fix that first before asking paid media to do the heavy lifting.