You think SEO is working. Someone who controls the budget has asked you to prove it, and when you go looking for a number to hand them, you struggle.
Search “SEO ROI” and you’ll find returns quoted anywhere from £1.75 per pound spent to £22, with plenty of sources putting the average north of 1,000%.
Hardly any of them show their working, and most were published by agencies selling the service. Take one of those numbers into a meeting with your finance director and you’ll spend it defending the source instead of the budget.
It isn’t that SEO fails to pay back, because it usually does. It’s that the figures doing the rounds are built on half an equation, and the half they leave out is the one your finance team asks about first.
This article hands you the model rather than the verdict, then runs two real campaigns through it.
The Honest Answer Is “Normally, yes”, But Here Is What It Depends On
Whether organic search is worth funding for your business comes down to three numbers.
- How much search demand there is in your category. Not whether people look for you by name, but whether they look for the problem you fix.
- What a customer is actually worth to you. Not the first purchase on its own, but the lifetime value of everything that follows it.
- How many of your visitors convert. A site that converts at 0.4% needs three times the traffic of one converting at 1.2% to produce the same result, and buying that traffic is usually more expensive than fixing the conversion rate.
If you have clear demand, valuable customers and a website that works, the answer is easy. If two of those three are missing, it probably isn’t, and there’s a section near the end of this article about what that looks like.
SEO Is a Capital Cost Dressed Up as a Monthly Invoice
Stop paying for PPC and the traffic stops that afternoon. Stop paying for SEO and visibility fades over months, sometimes years.
That difference is why the two don’t belong on the same line of a monthly cost sheet. PPC is an operating expense that buys immediate access. SEO is closer to buying an asset in instalments, where the payments stop before the returns do.
Across our client portfolio, organic performance doesn’t hold up forever once SEO activity stops. Competitors keep publishing, technical debt piles up and content ages out of relevance. What we tend to see is slow erosion rather than a cliff edge. This is a real advantage over paid media and one that rarely makes it into an ROI model.
When you put this to your CFO, the argument is simple enough: money spent on organic search carries on working after the invoice is paid, for a while, at a rate that tails off.
What an SEO ROI Model Actually Needs
The Cost Side
Most published SEO ROI figures divide the return by the agency fee and stop there.
A fuller picture takes in the retainer or in-house salaries, content production, developer time, tooling and platform costs, and whatever internal time goes into reviewing and reporting. Sometimes an agency covers all of that anyway, in which case the single figure is fine.
The Revenue Side
For ecommerce, organic revenue is where you start rather than where you finish. A first purchase isn’t the value of the customer it won you. If a decent share of those buyers come back, the campaign that brought them in carries on earning long after the reporting period closes, and a twelve-month figure captures none of that.
Use lifetime value where your data supports it, or a conservative but educated estimate where it doesn’t. Either way, a model built on first purchases alone will understate what you actually got.
For lead generation, it’s closing rate multiplied by average deal value, pulled from your CRM. The same point applies in a different shape: a first contract, or a first monthly payment, isn’t the value of the relationship, and for retained or subscription models that gap is big.
The Time Side
An annual return quoted at month three tells you nothing. Organic tends to build slowly and then compound, so the line sits flat for a while before it ‘hockey sticks’.
What your finance team actually needs to see is the payback window: the point at which cumulative return overtakes cumulative cost. Rather than locking yourself into a rigid monthly target or promising a static annual figure, model a realistic time range for that crossover.
Show the actual shape of the curve, set clear expectations around that payback window, and give your stakeholders a forecast you can aim for.
| Input | Where the figure comes from | How it usually goes wrong |
| Agency or in-house cost | Invoices / salary plus overhead | Treated as the only cost |
| Content production | Writer, design and asset costs | Absorbed into “marketing” and forgotten |
| Developer time | Sprint allocation, day rate | Excluded because it is internal |
| Internal management time | Time spent briefing and reviewing | Never counted at all |
| Revenue or lead value | GA4, CRM close rate, average deal value | Estimated rather than pulled |
| Customer lifetime value | Repeat purchase data | Ignored entirely |
| Payback period | Cumulative cost against cumulative return | Replaced with an annual percentage |
Two Campaign Examples
Here are two ROI examples from our own client work.
Example One: Parcel and Logistics Brand
Over twelve months, growth came from more visitors arriving from organic search, and more of those visitors going on to buy.
| Metric | Change |
| Organic revenue | Roughly doubled |
| Organic transactions | +136% |
| Purchaser rate | 0.96% to 1.39% |
Set against the retainer, the campaign produced roughly £25 of organic revenue for every £1 spent. That’s a revenue ratio rather than a return on investment, and turning one into the other needs the client’s gross margin, which is confidential.
What we can say is that the campaign broke even at a gross margin of 3.98%, so any business clearing 4% or better made money on it. Here’s how the ROI looks across a range.
| Gross margin | Return on investment |
| 10% | 151% |
| 20% | 402% |
| 30% | 653% |
| 50% | 1,155% |
That figure counts only what those customers spent inside the twelve months, so any repeat business sits outside it. Which makes 3.98% a conservative reading rather than a flattering one.
Example Two: Specialist High Value Training Business
Nine months, and a total investment of £27,000.
| Metric | Before | After |
| Organic sessions | 16,965 | 45,563 |
| Organic conversions | 449 | 1,768 |
| High-value enquiries | 40 | 240 |
| Conversion rate | 2.65% | 3.88% |
Cost per extra high-value enquiry: £135. Cost per extra enquiry of any type: £69.
We don’t hold this client’s average deal value, so the same break-even framing applies. The campaign paid for itself if those 200 extra enquiries produced £27,000 of gross profit between them. Given the products and services offered are high-value, you can draw your own conclusion about whether it cleared that.
The point of showing both isn’t that organic search returns £25 a pound. It’s that the same method gives you an answer at either end of the scale, from small business to enterprise, and you can run it on your own figures.
Where SEO and PPC Each Earn Their Place
The useful comparison between organic and paid isn’t which one wins. It’s how their unit costs behave over time.
The cost of your next paid click is set by the auction and level of competition. The cost of your next organic visit falls as the asset matures, because the work that earned the ranking has already been paid for.
Example one picked up an extra completed transaction for £2.42. Cost per click on the commercial terms in this subject area currently runs between £2.16 and £8.84 in the UK. The campaign bought a finished sale for roughly the price of one paid click.
| Paid search | Organic search | |
| Time to first return | Days / weeks | Months |
| When you stop paying | Traffic ends immediately | Declines gradually |
| Attribution clarity | High | Moderate |
| Control over volume | Direct | Indirect |
Paid search buys certainty and speed at a known unit cost, which is exactly what you want when you have a quarter to show results. Organic buys a falling cost base but with a slower start.
Most businesses running both are doing the sensible thing, and the IPA’s Q2 2026 Bellwether report suggests UK marketing budgets are being revised up rather than shuffled between channels.
What AI Overviews Do to the Model
Clicks are down across all sectors, everybody is in the same boat. Pew Research Center’s analysis of the browsing behaviour of 900 US adults found that 8% of searches showing an AI summary produced a click, against 15% of those without one.
SparkToro’s analysis of Similarweb clickstream data puts the zero-click share of US Google searches at 68.01% between January and April 2026, up from 60.45% in 2024.
What matters for your model is that the drop in clicks isn’t spread evenly.
Semrush’s analysis of more than 600,000 keywords between November 2025 and April 2026 found AI Overviews grew 71% on commercial-intent SERPs while falling 5% on transactional-intent queries.
Tracking by Seer Interactive across 53 brands and 5.47 million queries puts the prevalence of AI Overviews at 36% of informational queries, 8% of commercial queries and 5% of transactional ones.
In other words, the queries closest to a purchase are the ones AI Overviews barely touch. Someone researching how something works may well get their answer without clicking (although they will become aware of your brand if you are mentioned). Someone ready to buy still ends up on a website.
The modelling consequence is direct: build your return on converting queries rather than total traffic growth. A site that has lost a third of its informational traffic and almost none of its commercial traffic has lost far less money than its traffic graph suggests.
Presence counts too, even where the click doesn’t follow. Seer’s data shows that being cited in an AI Overview delivers roughly 120% more organic clicks per impression than sitting on the same result page uncited. Being in the answer set matters, and we measure this on client campaigns.
What to Do If You Cannot Get Clean Attribution
Most attribution is imperfect. Organic search takes last-click credit for demand it never created, and loses credit for demand it did. If you’re holding out for clean data before you build a case, you’ll be waiting a long time. Three things that help:
- Track branded search volume as a demand proxy. Rising branded search is one of the clearer signs that your upper-funnel content is doing its job.
- Report assisted conversions alongside last click. Last click on its own will understate what organic contributed to journeys that finished somewhere else.
- Present the case directionally, and say so. A range with its assumptions on show is more credible to a finance audience than an exact number you can’t defend.
If your programme has been running a while and none of the numbers are shifting, the problem may be delivery rather than measurement. We have written separately about how to tell the difference.
When SEO Is Not Worth It
Low search volume on its own doesn’t rule organic search out. It only becomes a problem when it’s paired with low customer value. Two hundred searches a month for something worth £20,000 a sale is a strong case. Two hundred searches a month for a £15 product isn’t.
If you run a specialist, high-value, low-volume business and someone has told you organic search isn’t for you, there’s a fair chance they were wrong.
The conditions that genuinely do rule it out:
- A runway shorter than your payback window. If you need revenue this quarter, the honest answer is paid media. Organic search can’t be hurried into a cash flow gap.
- A website you can’t or won’t change. Where the platform is broken and there’s no route to fixing it, content investment produces nothing.
- Revenue built on a handful of large negotiated relationships. If your growth comes from three accounts and a procurement process, search volume isn’t your constraint.
- A conversion rate problem in disguise. If your site converts at 0.3%, doubling the traffic just doubles a small number. Improving conversion rate is usually the first port of call, and it makes every channel you invest in afterwards work harder. We have run campaigns where we took this approach.
Conclusions
For most businesses, organic search pays back, and at a unit cost paid media can’t match once the asset has matured. For a smaller number it doesn’t, and for anyone unwilling to measure it properly the question stays unanswerable.
You don’t need our figures. You need your own three numbers, a cost side with everything in it, and a payback window you’re willing to work towards. If you’d like a second opinion on what those look like for your business, get in touch today.
Hi! I’m Ben, CEO of The SEO Works
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