One of the first questions businesses ask when setting up Google Ads is: "How much should we spend?"
There's no universal answer. A local plumber needs a different budget than a national e-commerce retailer. But there are proven frameworks that help you find the sweet spot—the budget that delivers strong results without overspending or underselling your potential.
Let's break down exactly how to think about Google Ads budgeting so you spend confidently and track what you're getting back.
The Three Ways to Think About Budget
The Objective-Based Method (Most Effective)
This is the most practical approach for small and medium businesses. You start with your business goal and work backwards to determine budget.
Here's the formula:
- Define Your Goal — "I want to generate 50 qualified leads this month" or "I want £10,000 in revenue"
- Know Your Conversion Rate — How many clicks typically result in a conversion? If 5% of clicks convert, you need 1,000 clicks for 50 leads
- Estimate Your Cost Per Click (CPC) — Google Ads doesn't charge per lead or sale; it charges per click. Industry average CPCs range from £0.50 in low-competition industries to £5+ in competitive ones
- Calculate Total Budget — 1,000 clicks × £2.50 average CPC = £2,500 monthly budget
Example: Local Service Business
You're a plumber wanting 20 qualified leads monthly. Your historical data shows that 8% of clicks result in a lead inquiry. Your industry average CPC is £1.80.
Calculation: 20 leads ÷ 0.08 conversion rate = 250 clicks needed. 250 clicks × £1.80 CPC = £450 monthly budget.
Example: E-Commerce Business
You sell online courses. Your average order value is £97. Your historical data shows 3% conversion rate (3% of clicks purchase). You want £5,000 in monthly revenue, which is roughly 52 sales needed. Your average CPC is £0.75.
Calculation: 52 sales ÷ 0.03 conversion rate = 1,734 clicks needed. 1,734 clicks × £0.75 CPC = £1,300 monthly budget.
Industry Benchmark CPCs (UK Average)
These give you a realistic sense of what you should expect to pay per click in your industry:
- Legal Services: £15–£75 per click (highly competitive, high value)
- Insurance: £8–£30 per click
- Real Estate: £5–£20 per click
- Technology/SaaS: £3–£10 per click
- E-Commerce: £0.50–£3 per click
- Local Services (Plumbing, Electrician, etc.): £1–£5 per click
- Fitness/Wellness: £1–£5 per click
- Travel: £0.50–£4 per click
- Financial Services: £5–£50 per click
If your CPC is way higher than these benchmarks, you might be bidding too aggressively or have low-quality ads. If it's significantly lower, you may be missing opportunities or have a blue-ocean advantage—either way, investigate.
Budget Strategy by Business Stage
Testing Phase
Just starting? Budget £300–£500 monthly to test different campaigns, keywords, and ads. Don't go big until you understand what works. Most businesses find their winning formula within 4–6 weeks at this spend level.
Growth Phase
Once you've proven a positive ROI, scale gradually. Increase budget by 20–30% monthly and monitor if performance stays consistent. This phase typically runs 3–6 months and focuses on expansion to new keywords and audiences.
Optimisation Phase
You're scaling steadily. Now focus on improving efficiency: lower CPC through better quality scores, higher conversion rates through landing page optimisation, and better targeting. Budget stays stable while results improve.
Dominance Phase
You've achieved strong, consistent ROI. Budget aggressively to capture market share. Scale to multiple ad types (search, display, shopping), new markets, and broader audiences. Budget might be 5–10x your initial spend.
How to Calculate Your Ideal Cost Per Acquisition (CPA)
This matters more than raw budget. If you spend £1,000 and acquire 10 customers at £100 each, that's sustainable only if those customers are worth more than £100 long-term.
The formula:
Maximum CPA = (Average Customer Lifetime Value) × (Acceptable ROI margin)
Example: Your customers spend an average of £500 over their lifetime with you. You want a 3:1 return (for every pound spent on ads, you want £3 back). Your maximum acceptable CPA is £500 ÷ 3 = roughly £167.
This means you can justify spending up to £167 to acquire each customer because they're worth £500 to your business. If your actual CPA is higher, you're losing money. If it's lower, you're in profit.
Golden Rule: Always know your numbers. Track how much you spend, how many conversions you get, and what those conversions are worth. Without this data, you're basically guessing. Use Google Ads conversion tracking, Google Analytics 4, or a CRM to connect ad spend to actual revenue. This transforms budgeting from hope into strategy.
Common Budget Mistakes to Avoid
Spreading Budget Too Thin — Running campaigns across 50 different keywords with a tiny daily budget often results in insufficient data to optimise. Focus your budget on your top 10–15 keywords and let Google's algorithms work with real volume.
Not Adjusting for Seasonality — E-commerce businesses need more budget during peak seasons (November–December). Service businesses might need more in spring. Adjust monthly based on your business cycle.
Stopping Too Early — Most campaigns need 2–4 weeks and at least 50–100 conversions before you have enough data to optimise. If you stop after a week, you'll miss the improvement that comes with learning.
Ignoring Quality Score — A low quality score inflates your CPC. Improve your ads, landing pages, and keyword relevance first, then budget follows naturally.
Setting Budget Above Profitability — Just because you can spend £5,000 monthly doesn't mean you should. Only increase budget if your ROI remains positive.
Monthly Budget by Business Model
| Business Model | Startup Phase | Growth Phase | Scale Phase |
|---|---|---|---|
| Local Service | £300–£600 | £800–£2,000 | £2,000–£5,000 |
| E-Commerce | £500–£1,500 | £2,000–£5,000 | £5,000–£25,000+ |
| B2B/Lead Gen | £600–£1,500 | £2,000–£6,000 | £6,000–£15,000+ |
| SaaS/Software | £1,000–£2,500 | £3,000–£8,000 | £8,000–£30,000+ |
For a detailed analysis of your specific budget needs and what you should expect to spend, book a free Google Ads audit. We'll review your industry, competition, and goals to recommend the budget that delivers the best results for your business.
Or explore PPC pricing packages designed for different business sizes, or create your custom package to match your exact needs.
The Verdict
There's no magic budget number—only the budget that aligns with your goals and delivers positive ROI. Start with the objective-based method: define your goal, calculate backwards to required clicks, and set budget accordingly. Begin conservatively, test your assumptions, and scale gradually as you prove results. Track everything, know your numbers, and adjust monthly. The right budget isn't about spending big—it's about spending smart.
Brett Dixon
Founder & Managing Director of DPOM. Brett founded DPOM nearly 15 years ago after a career in marketing working with Harvey Nichols, BBC Top Gear, Formula One circuits, and UK Trade and Investment. His passion became helping smaller businesses grow — with honest advice, no jargon, and realistic expectations.
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