“How much should I spend on Google Ads?” doesn’t have a universal answer — $500 a month could be plenty for one business and nowhere near enough for another, depending entirely on the numbers behind your specific offer. Here’s how to actually calculate a realistic budget instead of guessing or copying a number from a random article.
Start With Your Numbers, Not a Dollar Amount
Before picking a budget, you need three figures: your average customer value, your realistic conversion rate from click to customer, and the average cost per click for your target keywords. Without these, any budget number is a guess dressed up as a plan.
Step 1: Know Your Customer Value
This is the average revenue (or profit, if you want to be more conservative) from a typical customer, including repeat business if that’s common in your industry. A $50 one-time service and a $3,000 project with recurring maintenance can support wildly different ad spend, even at the same conversion rate.
Step 2: Estimate Your Cost Per Click
Google’s Keyword Planner (free with a Google Ads account) gives estimated cost-per-click ranges for your target terms. Competitive terms like “personal injury lawyer” can run $50+ per click in some markets; a specific local service term might be under $2. This range alone often explains why the same monthly budget works great for one business and does almost nothing for another.
Step 3: Estimate Your Conversion Rate
If you don’t have historical data yet, 2-5% is a reasonable starting estimate for a well-built landing page with clear intent-matched keywords — meaning roughly 1 in 20 to 1 in 50 clicks becomes a lead or sale. This will vary by industry and offer, but it’s a workable starting assumption for your first budget calculation.
Putting the Numbers Together
If your average cost per click is $3, and your conversion rate is 3%, you need roughly 33 clicks to get one customer — about $100 in ad spend per customer acquired. If your average customer is worth $500, that’s a strong return. If your average customer is worth $80, that budget doesn’t work at that cost per click and conversion rate, and something needs to change before spending seriously — a better landing page, more specific keywords, or a different customer value entirely.
A Realistic Minimum to Actually Learn Something
Whatever your calculation suggests, budget enough to generate at least 20-30 clicks a week in the first month — below that, you won’t gather enough data to make informed adjustments, and every decision will be a guess based on too few data points. If your ideal budget from the math above can’t support that volume, either your cost-per-click keywords need to be more specific, or ads may not be the right channel yet.
Budget Pacing Once You’re Running
Once a campaign is live, budget pacing — how evenly your spend is distributed across the month rather than front-loaded or exhausted early — becomes its own thing to manage, which we cover in detail in our Google Ads budget pacing guide.
Where This Fits Into Your Bigger Marketing Picture
A realistic ads budget comes from your actual numbers, not a generic recommendation. If you’re still deciding between ads and SEO first, our comparison guide can help you think it through, and I offer a free consultation to work through the numbers for your specific business.