SEO vs paid ads: which brings cheaper enquiries in the UK?
The same enquiry can cost £40 or £400 depending on which channel produced it and how far ahead you are willing to look. Here is how to work out the answer for your own business.
By Raoul (Alex) Müller, Founder ·
In the UK, paid ads usually produce the cheaper enquiry in the first three months and SEO usually produces the cheaper enquiry after twelve. Ad costs repeat with every click, while most SEO costs are spent once and keep working. To find your own answer, divide each channel’s total monthly cost by the number of qualified enquiries it produced, and compare the two over at least a year.
Cost per enquiry is the only number that settles it
Most arguments about SEO and paid ads never finish, because the two sides are counting different things. One talks about impressions and click-through rate. The other talks about rankings and traffic. Neither tells an owner what they need to know, which is what one new conversation with a buyer costs.
Cost per enquiry ends the argument. Take everything you spent on a channel in a month, divide it by the qualified enquiries it produced, and you have a number that compares against anything else you spend money on — a directory listing, a trade show, a van livery.
The word qualified is doing real work in that sentence. A qualified enquiry is someone who wants what you sell, in the area you serve, who left enough detail for you to reply. Form spam, wrong numbers and people asking for a job all have to come out before you divide. Skip that step and both channels will flatter themselves.
Add the spend, the fee and the tools
Ad spend plus management fee plus any landing page or tracking costs, divided by qualified enquiries in the same month. Ads react quickly, so a single month is usually a fair window once the account has settled. Read how we manage paid ads to a cost per qualified enquiry rather than to clicks.
Use a rolling year, not a single month
Monthly fee plus content production plus tools, divided by qualified enquiries from organic search. One month tells you very little here, because this month’s enquiries came from work done three to nine months ago. Once you have twelve months of data, average it.
A worked example, with illustrative figures
The figures below are invented to show the shape of the maths. They are not client data, they are not a case study, and they are not a forecast for any business.
Picture a hypothetical bathroom fitting company in a mid-sized English city. It spends £1,900 a month on Google Ads once the management fee is included, and £995 a month on an SEO programme. Both channels are tracked the same way, and only qualified enquiries are counted.
| Period | Paid ads (illustrative) | SEO (illustrative) |
|---|---|---|
| Months 1–3 | £1,900/month · 15 enquiries · £127 each | £995/month · 4 enquiries · £249 each |
| Months 4–12 | £1,900/month · 17 enquiries · £112 each | £995/month · 14 enquiries · £71 each |
| Months 13–24 | £1,900/month · 17 enquiries · £112 each | £995/month · 26 enquiries · £38 each |
Two things in that table are worth sitting with. The first is that paid ads win the opening quarter comfortably and then stop improving much. Once an account is well built, the price of a click is set by the auction, and the auction does not care how long you have been bidding in it.
The second is what happens when the money stops. Switch the ads off on a Friday and the enquiries stop on the Friday. Stop the SEO work and the pages keep ranking, decaying slowly rather than disappearing. Ads rent attention; SEO buys an asset that needs maintaining.
Change the inputs and the story changes. Halve the search volume in that city and the SEO column never reaches £38. Double the click price and the ads column never reaches £112. Which is why any agency quoting you a cost per enquiry before looking at your market is guessing.
Why your market changes the answer
Four features of a market decide which channel is cheaper, and none of them are about how good the agency is.
What a click costs
Some categories are brutally expensive to advertise in. Personal injury, insurance, cosmetic dentistry and enterprise software routinely clear £10 a click and can go a long way past it. Paid ads still work in those markets, but they are rarely cheap, and organic visibility is worth a great deal more.
How many people are searching
If forty people a month search for what you sell, no amount of SEO builds a large channel, and ads will not either. Very small markets are usually won through referral, outbound and partnerships, and honest advice says so instead of selling a retainer into thin air.
What a customer is worth
A firm whose average customer is worth £12,000 can pay £400 for an enquiry and be pleased. A firm selling a £90 service cannot. Cost per enquiry only means something beside customer value and the share of enquiries you convert.
How strong the incumbents are
If the first page is filled with national brands carrying thousands of referring domains, organic progress is slower and costs more. Ads sit above all of it from day one, which is sometimes worth paying for while the slower work builds underneath.
Why your timeframe changes the answer even more
Choose a three-month window and paid ads win almost every time. Choose a three-year window and SEO usually wins by a distance. Both statements are true, which is why the question cannot be answered without a timeframe attached to it.
The useful version is this: how long are you prepared to fund something before it pays you back? If the honest answer is six weeks, run ads. If the honest answer is a year, a structured SEO programme is likely to be the cheaper channel across that year and every year after it.
There is a second effect that rarely makes the comparison. Organic pages are what AI assistants read. Google’s AI Overviews, ChatGPT, Gemini, Claude and Perplexity summarise crawlable content and cite sources; none of them read your ad account. Our summary of how one UK health brand earns citations at scale shows what that reaches once it has compounded for years.
Where paid ads genuinely win
There are situations where recommending SEO first is simply wrong advice, and an agency that never says so is selling rather than advising.
- ✓You need enquiries this month. A quiet quarter, a new hire to keep busy, a cash flow gap — SEO cannot help with any of those, and pretending otherwise wastes a quarter.
- ✓You are testing an offer, a price or a new town. Ads buy you a verdict in weeks, for a few hundred pounds, before you commit to building pages around an assumption.
- ✓Your service is bought in an emergency. Emergency plumbing, locksmiths, vehicle recovery, urgent legal help — the buyer clicks the first credible result and stops looking.
- ✓Search volume is small but each customer is worth thousands. Twenty searches a month will never build an organic channel, but twenty well-targeted clicks might be a very good month.
- ✓Your website is genuinely too weak to rank soon. A brand new domain, thin pages, or a rebuild six months out. Ads carry the business while the foundations are laid.
- ✓You want to reach people who already visited. Retargeting has no organic equivalent, and it often carries the cheapest conversions in the whole account.
- ✓Your market is seasonal and the season is now. A boiler servicing firm in October cannot wait for a page to mature by February.
How to run both without wasting either
Most businesses that get this right are not choosing. They are sequencing, and they are letting one channel inform the other.
Let ads tell you what converts
If you are unsure which searches produce customers, run ads first. Within two months the search terms report shows which phrases produced enquiries and which only produced clicks. Expensive research, but real research, and better than a keyword tool guessing on your behalf.
Build pages for the terms that already paid
Feed the converting terms into the content plan. You are no longer hoping a page earns its keep; you have evidence that people searching that phrase become customers. That alone removes most of the waste from a first-year programme.
Move budget as the numbers move
As organic enquiries grow, some ad groups become redundant and the saved spend funds more content or authority work. Review the split every quarter on cost per enquiry, not on instinct.
Tie every enquiry back to where it came from
None of this works if enquiries arrive in a shared inbox with no idea what produced them. A CRM that captures the source with every enquiry is what turns this comparison from an opinion into a report you can act on.
One caution. This comparison only works if both channels are competently run. A badly built ads account will look expensive when the problem is the account. An SEO programme producing blog posts and no technical work will look useless when the problem is the plan. Fix the execution before you judge the channel.
Work out your own number
Send us your site and what you currently spend, and we will tell you honestly which channel we would start with and why — including the times we would say ads first. Digital Movement UK works on rolling monthly agreements, so the advice has to keep being right.
Ask us which channel to start with