How much should you spend on Google Ads?

By Ahmed Imran · Updated June 2026 · 8 min read

Your Google Ads budget should be set by arithmetic, not by a rule of thumb. Take the average cost per click in your category, multiply by the clicks you need to produce 15 to 30 conversions a month so Smart Bidding can learn, and that number is your floor. For most US small businesses that lands between $1,500 and $3,000 a month, and it climbs fast in expensive categories like legal.

The most common question I get before an engagement starts is what the ad budget should be, and almost every answer online is a range with no math behind it. A budget is not a preference. It is a calculation, and the two inputs are the cost per click in your category and the number of conversions Google's bidding algorithm needs before it can optimize anything.

I have run US accounts spending $5,000 in a launch month and accounts spending $344,000 in 30 days. The arithmetic that sets the floor is identical at both ends. Here is how to run it.

How do you calculate a Google Ads budget?

You calculate a Google Ads budget by multiplying your category cost per click by the number of clicks required to generate 15 to 30 conversions a month. That is the whole formula. Everything after that is negotiation with yourself.

Written out: monthly budget floor equals your target conversions divided by your conversion rate, multiplied by your cost per click. You need four numbers.

• ›Target conversions. Google names 15 conversions in a 30 day window as the point where Smart Bidding becomes viable, and recommends closer to 30 for Target CPA. Use 30 if you can afford it.
• ›Conversion rate. Use your own if you have 90 days of clean data. If you do not, LocaliQ's 2026 Search Advertising Benchmarks put the cross industry average at 8.18 percent.
• ›Cost per click. LocaliQ's 2026 report puts the all industry average at $5.42, ranging from $2.05 in restaurants and food up to $9.87 in legal.
• ›The output. Clicks needed multiplied by cost per click gives you the monthly floor, before management fees and before landing page work.

Here is the arithmetic with those averages. To get 30 conversions at an 8.18 percent conversion rate you need 367 clicks. At $5.42 a click that is $1,989 a month. Drop the target to Google's bare minimum of 15 conversions and you need 184 clicks, or $997 a month. So the honest average answer is that a US small business needs roughly $1,000 a month to keep Smart Bidding alive and closer to $2,000 a month for it to actually work.

Now run the same formula for a personal injury firm. LocaliQ's 2026 data puts legal cost per click at $9.87 with a 5.55 percent conversion rate. Thirty conversions requires 541 clicks, which is $5,340 a month. That is why $1,500 in legal produces almost nothing, while the same $1,500 in auto repair, where cost per click is $4.35 and conversion rate is 15.51 percent, buys about 345 clicks and roughly 53 conversions. Same budget, completely different outcome, and the only variable is the category.

What is the minimum budget to make Google Ads work?

The minimum is whatever produces 15 conversions in 30 days in your category, because that is the threshold below which the algorithm never leaves the learning period. In practice that ranges from about $450 a month in auto repair to about $2,000 a month in legal.

An underfunded account fails in a specific and predictable way. Smart Bidding needs a volume of conversion events to model which auctions are worth winning. Under 15 in a rolling 30 days, every signal is noise. You get four conversions in a month, two of them from the same zip code, and the algorithm draws conclusions from nothing. Then it draws different conclusions next month.

There is a second problem underneath that one. When a campaign is capped tight, Google reports it as limited by budget and spreads impressions thinly rather than concentrating spend on the auctions most likely to convert. You end up buying a thin slice of a lot of weak inventory instead of a concentrated slice of the good stuff.

Those cost per lead figures come from LocaliQ's 2026 Search Advertising Benchmarks, built from thousands of Google Ads and Microsoft Ads campaigns across 23 industries. Treat them as a starting point rather than a promise. Your own cost per lead after 90 days is the only number that ends up mattering.

Should you budget from a percentage of revenue?

No. The common advice to spend 5 to 10 percent of revenue on marketing is a planning ceiling for the whole marketing function, not a Google Ads budget, and using it as one is how businesses end up funding a campaign that mathematically cannot work.

Consider a company doing $600,000 a year. At 7 percent that is $42,000 annually, or $3,500 a month spread across every channel. Google Ads might get $1,500 of it. If that company sells commercial paving, where I have seen leads cost $186.73, $1,500 buys eight leads a month and Smart Bidding never stabilizes. The percentage was perfectly reasonable. The outcome was still failure.

Work backward from unit economics instead. Four numbers get you to a defensible answer.

• ›Average customer value. What one closed customer is worth in gross profit, not revenue.
• ›Close rate on ad leads. The share of Google Ads leads that become customers. Use 20 percent as a placeholder until you have real data, and expect paid leads to close worse than referrals.
• ›Maximum acceptable cost per acquisition. Customer value multiplied by the share of it you are willing to hand over for growth.
• ›Maximum cost per lead. Your acceptable cost per acquisition multiplied by your close rate. This is the number you compare against the benchmark table above.

Say a closed customer is worth $4,000 in gross profit and you close 20 percent of ad leads. If you will spend 25 percent of gross profit to acquire one, your ceiling is $1,000 per customer, which works out to $200 per lead. Now check that against your category. If your benchmark cost per lead is $90, you have real room, and your budget becomes a question of how many customers you want. If your ceiling is $40 and your category runs at $130, no budget fixes that. The offer or the close rate has to change first.

How do you know when to scale the budget?

Scale when your cost per acquisition has held at a profitable level for at least 30 days and Google reports the campaign as limited by budget. If either condition is missing, more money makes the problem bigger rather than smaller.

Limited by budget shows up in the campaign status column and means you are losing impressions you could have won. That is evidence demand exists above your current spend. A stable, profitable cost per acquisition across a full 30 day window is evidence that buying more of that demand is a good idea. You need both.

Raise in increments of about 20 percent, never doubles. A large budget jump can push Smart Bidding back toward learning, and you will burn two weeks unable to tell whether the new spend level actually works. I move an account from $5,000 to $6,000, hold for two to three weeks, read cost per acquisition, and only then move again. Doubling overnight is how a $60 cost per lead quietly becomes $140 with no explanation anyone can reconstruct.

• ›Cost per acquisition has been stable and profitable for 30 days, not 7.
• ›The campaign status reads limited by budget, and search impression share lost to budget is meaningful rather than 3 percent.
• ›Your sales side can absorb the extra volume. I have watched good campaigns get blamed for lead quality when the real issue was nobody calling back within an hour.
• ›Conversion tracking is clean enough that you trust the cost per acquisition you are about to bet more money on.

Then watch cost per acquisition after each step. Some accounts scale in a straight line for a long time. Dr. Laleh's account absorbed $161,000 over twelve months and still produced $803,000 in tracked booking value at 4.99x. Others hit a ceiling where each increment costs more than the last, and the right move there is to freeze the budget and go fix conversion rate instead.

What do real budgets look like?

Real budgets in my accounts run from $5,000 in a launch month to $344,000 in 30 days, and both ends are correct for the business they belong to. Here is the actual range with what each produced.

The pattern worth noticing is not the size of any single number. It is that every one of them is the output of the same calculation. Dandi Fertility launched from zero on a small budget and reached $18,000 in purchases at 6.62x within two months because the category cost per click was low enough that $5,000 bought genuine conversion volume in month one. The paving contractor needed a far larger budget for the same statistical footing purely because each lead cost $186.73.

Look at what a $110 cost per lead implies for a law firm. Big Chad Law runs roughly $40,000 a quarter, about $13,300 a month, which is around 121 leads a month. At $1,500 a month that same account would produce 14 leads and would sit right on the edge of the learning threshold every single month, never quite stable enough to optimize.

What happens if you spend too little?

If you spend too little, the campaign never exits the learning period, and you conclude that Google Ads does not work when the real problem was funding. This is the most common story I hear from people whose previous attempt failed.

The sequence is predictable. You set $500 a month. At the LocaliQ 2026 average cost per click of $5.42 that buys about 92 clicks. At the 8.18 percent average conversion rate, that is 7 or 8 conversions in 30 days, roughly half of what Smart Bidding needs to model anything. So the algorithm keeps guessing, and your cost per conversion swings from $40 to $180 month to month with no pattern you can act on.

The second failure is that you have nothing to optimize with. At 8 conversions a month you cannot tell which keywords convert or which landing page wins. I need conversion volume to make decisions, and no amount of skill substitutes for it. An account producing 8 conversions a month is not a smaller version of an account producing 80. It is a different thing, and it does not improve on its own.

So if your available budget genuinely sits below the floor for your category, the better move is almost always to narrow the campaign until the math clears rather than to run it thin. Cut to one city instead of five. Cut to your single highest value service instead of your full menu. A tightly narrowed $800 campaign producing 18 conversions beats a broad $800 campaign producing 6, every time.

And if even the narrowed version cannot reach 15 conversions in 30 days at your category cost per click, Google Ads is not the right channel for you right now. That is a legitimate answer, and I would rather say it before you spend $6,000 finding out.