How Much Should You Spend on Digital Marketing? A Budget Framework

There is no universal right answer to 'how much should I spend on digital marketing?' — but there is a right framework for arriving at the answer specific to your business. Most businesses set their marketing budget by one of three broken methods: a fixed percentage of revenue (arbitrary), 'what we spent last year plus 10%' (backwards-looking), or 'what we can afford' (not tied to growth objectives at all).

The right framework starts from desired outcomes and works backwards to required investment. Here's how to build a budget that's actually tied to your business goals.

Step 1: Define your growth target in revenue terms

Marketing budgets should be determined by revenue targets, not set first and then used to justify targets. Start with a specific, measurable goal: 'we want to grow revenue by £500,000 this year through new customer acquisition'. This number drives everything downstream.

Step 2: Calculate required new customers and leads

From your revenue target, work backwards through your business metrics. If your average customer value is £5,000 and you want to add £500,000 in new revenue, you need 100 new customers. If your close rate on qualified leads is 25%, you need 400 qualified leads. This is your annual lead generation target — the outcome your marketing budget needs to produce.

Step 3: Determine cost per lead by channel

If you have historical data, you already know your cost per lead from each channel. If you don't, use industry benchmarks as starting estimates, but plan to measure and update these within 90 days of any new campaign. The channel CPL landscape for typical professional services businesses:

Step 4: Calculate minimum viable investment by channel

Using your target CPL and required lead volume: if you need 400 leads and Google Ads costs £80 per lead in your market, your Google Ads budget is a minimum of £32,000 annually (£2,700/month). If SEO organic can deliver 150 of those leads at £25 each once established, your annual SEO investment of £15,000 (£1,250/month) will eventually supplement paid acquisition. The combination produces a blended CPL lower than either channel alone.

The industry benchmark as a sanity check

Benchmarks vary significantly by industry, but these are useful reference points. B2B companies typically spend 2–5% of revenue on marketing. B2C and e-commerce typically spend 5–12%. High-growth businesses targeting rapid expansion often invest 15–20% of current revenue to acquire future revenue. If your budget calculation suggests spending less than 2% of revenue on marketing, you're likely under-investing relative to growth ambitions. More than 20% suggests either very high competition, a new market entry, or inflated cost structures.

Splitting your budget: the channel allocation question

Channel allocation depends on your stage and goals. Early-stage businesses with no organic presence should weight towards paid acquisition (60–70% of budget) while organic assets are being built. Established businesses with strong organic presence can shift more to owned channels (SEO, email, content) that compound over time. The rule: channels that produce immediate results should be funded to the point of profitable ROI, then organic investment should compound alongside them.

What happens when the budget isn't generating ROI

Marketing budgets should be reviewed quarterly, not annually. If a channel is not generating leads at a profitable cost after 90 days (for paid) or 12 months (for SEO), the budget should be reallocated, not maintained by inertia. The discipline of tying budget decisions to measurable lead outcomes — not activity metrics — is what separates businesses that scale through marketing from those that simply spend more each year with diminishing returns.