How much should a store spend on Google Ads?

Automated bidding needs conversions to work with, so the first question is how much you must spend to generate a steady flow of them. Work it backwards from two numbers you can measure: the cost per click your products attract, and the rate at which clicks turn into orders.

Multiply them to get a cost per order, then decide how many orders a month the campaign should be producing for the bidding to settle rather than lurch. A campaign delivering a few orders a week will read as noise for a long time; one delivering several a day settles quickly. Where you sit between those depends on how much variance you can tolerate while it learns.

If that floor is more than you can commit, the honest answer is to narrow the campaign rather than to run it underfunded. A tightly scoped campaign on a small set of products at a spend that clears the floor will outperform a broad campaign spread so thin it never gathers signal.

The floor also rises with the number of campaigns. Splitting a budget across five campaigns divides the learning five ways, which is the most common reason a moderate budget performs worse than a smaller one did.

You cannot spend past the searches. Impression share tells you how close you already are: if you are showing on most of the eligible auctions and the share lost to budget is small, extra money will buy either worse traffic or the same traffic at a higher price.

Read the two lost impression share figures separately. Share lost to budget means there is demand you are not funding, and more money will buy more of the same. Share lost to rank means the auctions are going to someone else, and the fix is relevance, feed quality or price rather than budget.

When the obvious demand is covered, further spend has to come from new ground: additional product categories, new geographies, a different campaign type, or upper funnel work that creates demand rather than harvesting it. Those all have different economics, and folding them into the same budget line makes the account look like it is getting less efficient when it is actually doing a different job.

Seasonality moves the ceiling. A category with a concentrated buying season has months where the ceiling is far above your normal spend and months where it is below, and a flat monthly budget wastes both.

Average return across a campaign hides what is happening at the edge. As spend rises, the cheapest and most likely conversions are bought first, and each additional dollar buys progressively harder traffic. The campaign is worth expanding while that marginal dollar still returns more contribution than it costs.

Measure it by changing the budget in steps and watching what the increase itself produced. Raise the daily budget by a set amount, wait for the account to stabilise, and compare the extra revenue against the extra spend. If the extra spend returns above break-even, take another step. When it stops, you have found the practical ceiling for that campaign at that target.

That process is slower than picking a percentage of revenue, and it is the only method that gives an answer specific to your store. Percentage rules describe what other businesses spend and say nothing about what your margin can support.

Hold the reporting in contribution terms while you do it. A step that lowers the reported return and raises total contribution is a step worth keeping, and a rule written in ratios will tell you to reverse it.

Split the number before you spend it. Brand demand, acquisition, and remarketing behave differently and should be funded separately, otherwise the cheapest of the three quietly absorbs the budget and the account stops growing.

Allow for a test line as well. A fixed share set aside for new campaigns, new geographies or new creative gives the account somewhere to find its next source of volume, and keeps testing from competing with the campaigns that are already paying.

Then leave room outside Google Ads entirely. A store spending its whole marketing budget on one auction is exposed to that auction's price, and the same money in feed work, product page improvements or email flows frequently produces more contribution per dollar because it lifts the conversion rate on traffic you have already paid for.

Revisit the split quarterly rather than monthly. Enough happens in a month to make a change look justified, and not enough happens to know whether it was.