One of the most common questions small and medium-sized businesses ask before starting Google Ads is: how much should I spend? The honest answer is that there is no universal figure. The right budget depends on your industry's cost-per-click, your conversion rate, your average order or client value, and your growth ambitions. What this guide provides is a framework for calculating a budget that makes commercial sense for your business, rather than a number plucked from thin air.
Why Does "How Much Should I Spend?" Have No Simple Answer?
Google Ads budgets are shaped by three variables that differ significantly across industries and business types:
Cost-per-click (CPC): The price you pay each time someone clicks your ad. In competitive UK industries, CPCs vary enormously. A click for "personal injury solicitor UK" might cost £30 to £80. A click for "florist near me" might cost £0.50 to £2. Your budget needs to accommodate enough clicks to generate statistically meaningful data and a viable number of leads.
Conversion rate: The percentage of clicks that result in a contact form submission, phone call, or purchase. A landing page converting at 2% needs 50 clicks to generate one lead. A well-optimised landing page converting at 8% needs just 12 clicks for the same result. Your conversion rate determines how many clicks you need to buy to hit your lead volume targets.
Customer value: How much a converted customer is worth to your business. A business with a £50 average order value needs a very different economics model than a business with a £5,000 average client value. The latter can afford a much higher cost-per-lead and still generate a positive return.
How Do You Calculate a Break-Even Google Ads Budget?
Start with a break-even calculation before setting any budget. This tells you the maximum you can afford to spend per lead while remaining profitable.
Step 1: Calculate your maximum cost-per-lead (CPL)
If your average client value is £2,000 and you convert 1 in 5 leads to a client, your average lead value is £400. If your gross margin is 50%, each client generates £1,000 of margin. A lead-to-client conversion rate of 20% means each lead generates £200 of margin on average.
Your break-even CPL is therefore £200. Spending more than £200 to acquire a lead means you are losing money. Spending less means you are generating positive return.
Step 2: Calculate the clicks needed per lead
If your landing page converts at 4%, you need 25 clicks to generate one lead (100 / 4 = 25).
Step 3: Calculate your maximum CPC
If your break-even CPL is £200 and you need 25 clicks per lead, your break-even CPC is £200 / 25 = £8.
If the average CPC in your industry is £6, you have room to run a profitable campaign. If the average CPC is £15, you need to either improve your conversion rate, find cheaper keyword segments, or accept lower returns while you build volume.
Step 4: Set a starting budget
For meaningful data, aim to generate at least 100 clicks per month. At a £6 CPC, that is a £600 monthly budget. At £15 CPC, it is £1,500.
These figures represent a floor, not a target. Smaller budgets than this make it very difficult to accumulate enough data to optimise the campaign, because you are seeing too few clicks and conversions to distinguish signal from noise.
What Is a Realistic Starting Budget by Industry?
The following ranges reflect typical UK Google Ads CPCs and the minimum budgets needed to generate meaningful data. These are approximate and vary by location, competition, and keyword targeting:
Professional services (solicitors, accountants, financial advisers): £1,000 to £3,000 per month minimum. CPCs are high (£10 to £50+), but client values are also high, making the economics viable at larger budgets.
Trade and home services (plumbers, electricians, builders, landscapers): £500 to £1,500 per month. CPCs are moderate (£3 to £15), and local targeting keeps volumes manageable.
E-commerce: £500 to £2,000+ per month depending on product category. Shopping campaigns typically have lower CPCs than search, making e-commerce more accessible at smaller budgets.
Healthcare and aesthetics (dental, physiotherapy, cosmetic clinics): £800 to £2,000 per month. CPCs are moderate to high (£5 to £30) but client values justify the spend.
Hospitality and leisure: £300 to £1,000 per month. Lower CPCs but also lower margins, requiring efficient conversion.
Recruitment and HR: £500 to £1,500 per month. CPCs vary significantly by sector and seniority of roles.
How Should You Structure Your Budget Across Campaign Types?
Rather than putting all budget into one campaign type, consider how the buyer journey maps to different ad formats.
Search campaigns: The core of most SME Google Ads accounts. Search ads appear when someone types a relevant query. They have high intent because the user is actively searching. Allocate the majority of your budget here (60 to 80%) for most SMEs.
Google Shopping campaigns (e-commerce only): Shopping ads show product images, prices, and retailer names directly in search results. They are often more efficient than text search ads for product-focused queries. E-commerce businesses should allocate 40 to 60% of budget to Shopping.
Remarketing campaigns: Target users who have visited your website but not converted. CPCs are typically much lower than search (£0.10 to £1.00), and these campaigns are highly efficient because the audience is warm. Allocate 10 to 15% of budget to remarketing once you have sufficient website traffic (500+ monthly visitors is a reasonable threshold).
Performance Max campaigns: Google's automated campaign type that combines search, Shopping, display, and YouTube into a single campaign. Useful for e-commerce brands with larger budgets (£2,000+ per month), but requires sufficient data and careful exclusion management. Not recommended as a starting point for most SMEs.
How Do You Know When to Increase Your Budget?
Scale your budget when the campaign is demonstrably profitable and when increasing spend will maintain or improve your return on ad spend (ROAS).
Signs that your campaign is ready for increased budget:
- Your cost-per-lead is below your break-even threshold consistently across 30+ days
- Your campaigns are hitting daily budget limits regularly (meaning Google wants to spend more than you are allowing)
- Your Quality Scores are 7 or above on core keywords
- Your conversion tracking is working accurately and capturing the full value of conversions
When you increase budget, increase it by 20 to 30% at a time rather than doubling or tripling it. Large budget changes disrupt Google's automated bidding algorithms, which need time to re-learn the optimal bid distribution for the new budget level. Gradual increases maintain performance stability.
What Are the Most Common SME Google Ads Budget Mistakes?
Starting too small: A £200 per month Google Ads budget in a competitive industry generates so few clicks that meaningful optimisation is impossible. You will not see enough conversions to know which keywords, ads, or landing pages are working. Either commit to a viable budget or wait until you can.
Not tracking conversions: If you do not know which clicks are generating leads or sales, you have no basis for optimisation. Conversion tracking (via Google Ads conversion tracking or Google Analytics 4 goals) is non-negotiable. Set it up before spending a single pound.
Spreading budget too thinly: Running five campaigns targeting different product lines on a £500 budget means each campaign gets £100 per month, which is rarely enough to generate actionable data on any of them. Start with one or two campaigns focused on your highest-value service or product, build profitability, then expand.
Ignoring search terms reports: Google's broad and phrase match keywords can trigger ads for irrelevant queries. Review your search terms report weekly and add negative keywords for irrelevant traffic. Unmanaged broad match targeting wastes significant budget on low-quality clicks.
Setting it and forgetting it: Google Ads requires active management. Bids, ad copy, landing pages, keyword lists, and audience exclusions all need regular review and optimisation. An unmanaged campaign decays in performance as competition changes, Quality Scores fluctuate, and Google's automated systems drift without human oversight.
Should You Manage Google Ads Yourself or Use an Agency?
For businesses spending under £500 per month, self-management (with careful learning) can be viable if you have the time to invest in understanding the platform. Google's own Skillshop courses provide a reasonable foundation.
For businesses spending £500 to £2,000 per month, a specialist PPC agency or freelancer typically generates better returns than self-management, because the expertise required to manage campaigns profitably exceeds what most business owners can absorb on top of running their business.
For businesses spending £2,000+ per month, professional management is almost always the right choice. The cost of poor management at this spend level significantly exceeds agency fees.
When evaluating agencies, ask for case studies from clients in your sector, a clear explanation of their fee structure, and access to your own Google Ads account (never use an agency that owns your account rather than yours).
Dynamically manages Google Ads campaigns for UK SMEs across a range of budgets and industries. If you want a campaign built on commercial logic rather than guesswork, get in touch for a free account review and budget recommendation.
