Google Ads budget should be driven backward from your target cost-per-acquisition and close rate — not from an arbitrary monthly number. The right question is: given what a new customer is worth to my business, what can I afford to spend to acquire one? Working backward from that answer, with realistic assumptions about close rate and cost-per-click, gives you a budget range that's grounded in business math rather than guesswork.
The Business Math Behind Budget Decisions
Here's the framework for setting a Google Ads budget with numbers that make sense:
- Establish customer lifetime value (LTV): What is the total revenue a typical new customer generates over their full relationship with your business? Include repeat purchases, upsells, and referrals if they're predictable.
- Determine maximum acceptable customer acquisition cost (CAC): What percentage of LTV can you afford to spend acquiring a customer while still being profitable? For most service businesses, a CAC of 10–25% of LTV is sustainable; for e-commerce, ratios vary by margin structure.
- Estimate close rate: What percentage of qualified leads convert to customers? If you close 30% of qualified leads, you need roughly 3 leads for every customer acquired.
- Estimate cost-per-lead: This requires either historical data or a test budget. For initial testing, a range of $50–$150 per lead is common for service businesses, but varies enormously by industry and keyword competition.
- Calculate required budget: If you need 10 leads to get 3 customers (30% close rate) and your max CAC is $300, your max spend per customer is $300, meaning your max cost-per-lead is $100. To acquire one customer requires roughly $300 in ad spend, and to generate meaningful data you need at least 10–15 conversions, suggesting a test budget of $3,000–$4,500 over 4–6 weeks.
The Testing Phase: Why Starting Smaller Makes Sense
Spending heavily before establishing reliable cost-per-lead data is how Google Ads budgets get burned on the wrong keywords. A structured 4–6 week test with a modest budget — enough to generate 50–100 clicks on your target keywords — establishes real cost-per-click and conversion data that makes the scale decision far more reliable than any pre-campaign estimate. This approach also allows for early optimization: pausing poorly performing keywords, refining ad copy, and improving landing page conversion before the main budget runs.
Budget Allocation: Search vs. Display vs. Retargeting
For most small businesses new to Google Ads, allocating the majority of initial budget (80%+) to search campaigns targeting high-intent keywords is the right starting point. Search reaches people actively looking for what you offer, producing higher intent and therefore higher conversion rates than display or YouTube campaigns. Retargeting — showing ads to people who visited your site but didn't convert — should be a secondary allocation once the search campaign is generating site traffic. Display campaigns for cold audience awareness should generally be deprioritized until the search and retargeting foundation is performing well.
What Affects Cost-Per-Click in Your Market
Google Ads costs are auction-driven, which means they vary significantly by industry, geography, and keyword competition. Highly competitive industries (legal, financial services, insurance, SaaS) see CPCs ranging from $10 to $50+ for top keywords. Less competitive local service keywords can be $2–$10 per click. Utah County markets tend to be less expensive than major metro markets for the same keywords, which is a meaningful advantage for local businesses using Google Ads to compete with national players.