Most owners set a Google Ads budget by picking a round number that doesn't hurt too much — $1,000, $2,500, $5,000 — and then judge the channel by whether that number produced enough calls. That's backwards. Your budget is an output, not an input. It falls out of four numbers you already know or can estimate: gross profit per job, your lead-to-job close rate, the cost of a lead in your trade, and how many jobs you can actually service next month.
Here's how to run that math, and what current published benchmarks say about whether your answer is realistic.
Step 1: What you can afford to pay for a booked job
Start with gross profit on an average job, not revenue. Revenue per job is a vanity number — you can't spend it.
Take your average ticket, subtract labor, materials, and any subcontractor cost. What's left is what you're actually buying with ad spend. Then decide what share of that you're willing to hand to Google to acquire the job. There's no universal right answer; it depends on whether you're trying to grow, hold steady, or fill specific gaps in the schedule. Growth-mode businesses often accept a larger share because the customer may come back or refer someone. A shop running at capacity should accept a much smaller share.
Example, and these are illustrative inputs — use your own:
- Average HVAC replacement: $9,000 revenue, 35% gross margin → $3,150 gross profit
- Willing to spend 10% of gross profit to acquire the job → $315 max cost per sold job
Step 2: Convert that to a maximum cost per lead
You don't buy jobs. You buy leads — phone calls, form fills, booked appointments. So divide by your close rate.
If you sell 30% of the replacement leads you get:
$315 ÷ 0.30 = $105 maximum cost per lead
That one division is where most budget planning falls apart, because most owners don't actually know their close rate by lead source. If you don't know it, this whole exercise is guesswork dressed up as arithmetic. Estimate it now, then start measuring it — which is also why conversion tracking has to be right before any of these numbers mean anything (see our piece on the conversion tracking setup most local accounts get wrong).
Step 3: Check your max CPL against what leads actually cost
Now compare your ceiling to published market prices. WordStream's 2026 benchmarks, based on a sample of 13,474 US search campaigns running April 2025 through March 2026, report these medians:
| Category | CPC | Conversion rate | Cost per lead |
|---|---|---|---|
| All industries | $5.42 | 8.18% | $66.69 |
| Home & Home Improvement | $8.33 | 8.05% | $90.92 |
| Dentists & Dental Services | $8.00 | 10.67% | $72.97 |
| Attorneys & Legal Services | $9.87 | 5.55% | $131.63 |
Notice the relationship: cost per click divided by conversion rate equals cost per lead. At $8.33 a click and an 8.05% conversion rate, you need roughly 12 clicks per lead, or about $103. That's the same ballpark as the reported $90.92 median CPL for home improvement.
This matters more than the individual figures. It tells you there are exactly two levers on your cost per lead: pay less per click, or convert more of the clicks you already pay for. Landing page quality and Quality Score work on those levers. Budget does not.
In the HVAC example, a $105 ceiling against a market CPL near $91–$103 is workable but thin. Now run it for a $450 drain clearing job at 55% margin: $247 gross profit, 10% of that is $25 per sold job, and at a 50% close rate your ceiling is about $12 per lead. Nothing in the benchmark table gets you there. That's not a reason to skip Google Ads — it's the reason low-ticket repair work has to be bid as a door-opener to higher-ticket work, or targeted only where CPCs are cheap, or run through a pay-per-lead channel instead.
Step 4: Multiply by the jobs you can actually deliver
Budget follows capacity. If you have one crew with four open slots next month, funding twenty jobs' worth of leads just generates leads you'll answer slowly and lose.
Want 6 replacements next month, closing 30% of leads, at $95 per lead?
6 ÷ 0.30 = 20 leads → 20 × $95 = $1,900/month
That's a defensible starting budget. You can explain every term in it to your accountant.
The floor nobody tells you about
There's a complication: small budgets produce thin data, and thin data makes automated bidding unreliable. Google's own documentation on Smart Bidding recommends evaluating performance over periods containing at least 30 conversions — a month or longer — because below that you can't separate signal from noise.
At a $95 cost per lead, 30 conversions a month is roughly $2,850 in spend. Plenty of local businesses can't or shouldn't fund that on day one.
The answer isn't to spend more than the math supports. It's to shrink the target so a small budget buys real depth instead of a thin sheet of coverage. Narrow the radius to your most profitable zip codes. Cut to the five or six highest-intent keywords rather than sixty. Run one campaign, not four. A $1,200 budget concentrated on "ac replacement [city]" behaves like a real test. The same $1,200 spread across four campaigns and a whole metro behaves like a coin flip.
If you want the full sequence — keyword selection, campaign structure for small budgets, tracking, and the weekly routine that turns those numbers into decisions — that's what the Launchpad system walks through step by step.
How the budget field actually works
What you type into Google Ads is an average daily budget, not a cap. Google's help documentation is explicit about the limits: you won't be charged more than twice your average daily budget on any single day, and no more than 30.4 times your average daily budget in a calendar month. So convert monthly to daily by dividing by 30.4, not 30.
$1,900 ÷ 30.4 = $62.50/day
One recent change matters if you use ad scheduling. As of June 1, 2026, Google paces campaigns toward that full monthly limit — 30.4× your daily budget — even when your ad schedule only allows ads to run on certain days or hours. Previously pacing tracked closer to the number of active days. The billing caps didn't change, but the practical effect did: if you ran weekdays-only and treated your schedule as a soft spending control, that control is gone. Spend gets compressed into the hours your ads are eligible. If you day-part, lower the daily budget to match the monthly number you actually want.
Local Services Ads budget differently
If you're eligible for Local Services Ads, don't budget them the same way. LSAs are charged per valid lead rather than per click, and Google's Local Services documentation describes an average weekly budget with a monthly max calculated by multiplying that weekly budget by the average number of weeks in a month. Once you hit the monthly max, your ad stops showing for the rest of the month. Google also notes that leads judged invalid or low quality aren't charged, and charged leads get re-assessed over time and may be credited.
Google has also begun transitioning Local Services Ads into Performance Max campaigns with pay-per-lead goals, which converts the historical weekly budget to a daily average by dividing by 7 and removes manual max-cost-per-lead bidding. If you've been managing an LSA budget by hand, check which system your account is on before you plan around it.
When to raise the number
Raise your budget when two things are true at once: your campaigns are flagged as limited by budget, and your actual cost per booked job is comfortably under the ceiling you calculated in Step 1. If both hold, you're leaving profitable volume on the table, and the increase pays for itself.
If you're limited by budget but your cost per job is at or above the ceiling, more money makes the problem bigger. Fix the conversion side first.
And revisit the whole calculation quarterly. Your average ticket moves, your close rate moves, and the auction moves — WordStream's data shows median cost per lead across all industries fell slightly in 2026 while home improvement CPCs rose. A budget you can defend with four numbers is worth redoing when those four numbers change.