SEM (search engine marketing) is paid advertising on search engines: ads that appear among the results on Google or Bing when someone searches for a word you've bought, at a price set by an auction and charged almost always per click. In the UK that mostly means Google Ads, because in September 2026 Google handled 91.39% of searches against 6.08% for Bing (StatCounter).
On Google UK "search engine marketing" gets 5,400 searches a month, the same volume Google Ads assigns to the acronym "sem" (average of the last 12 months, Google Ads data via DataForSEO, October 2026). The acronym is a poor guide, though: on 10 October 2026 the first page for "sem" on Google UK was about scanning electron microscopes.
And under the full name, most of what you find is definitions.
On 10 October 2026 we opened the pages on the first page of Google UK for "search engine marketing": a glossary entry, an agency service page, guides dated 2023 and 2024 and one from Ahrefs updated in August 2026. In the six we read, not one gives a price for any tool. Where there are statistics they tend to be old: a 2019 BrightEdge report quoted by Ahrefs, a Statista projection for 2023 on Aumcore.
And the tools?
They do get named. Ahrefs' guide lists nine, from Keyword Planner to its own Keywords Explorer, and marks Google's as free, but says nothing about what the paid ones cost. Aumcore names Semrush and Optmyzr without a figure. So anyone who has to set up a campaign is left with the same question: what do I use, and what will it cost me?
It's the question we answer every week on the projects we manage. Valore Solare, which installs solar panels in northern and central Italy, works with us on ads only: 1,506 quote requests at €70.78 each (about £60), with the cost per request down 40% on the first quarter.
Macropix, an Italian LED wall manufacturer, has an unbroken Google Ads history going back to 2018: 2,906 enquiries, and in 2025 the lowest cost in the series, €39.44 (£33.42) per enquiry. We'll come back to it, because along the way there's a budget mistake worth telling.
In this guide you'll find:
- how the auction works, which decides who appears and how much they pay;
- the SEM toolbox, stage by stage, with the cost of each tool and how often it's searched for in the UK;
- whether Bing is worth it too, with UK market figures;
- where budget gets wasted, with the Macropix case.
Let's start.
SEM: what it really covers (and why we're not talking about SEO here)
Search engine marketing is everything a business pays for to appear in search engine results. Google itself, in its UK guide to SEM, says that "earlier definitions often included both paid and organic search strategies", but that "modern usage typically refers to paid initiatives".
That's the definition we use here.
But some people say SEM includes SEO.
True, and on Google UK both versions sit side by side: Ahrefs' guide counts SEO as part of SEM, the AI Overview describes paid ads only. Why the confusion exists and what changes between the two channels is in SEO and SEM: the differences, the costs and when to choose each. This guide starts where that one ends: you've decided to buy visibility, and now you have to do it.
The market you're entering is big. According to IAB UK's Digital Adspend study, published in March 2026, UK digital advertising was worth £40.5bn in 2025, and search accounted for 44% of it, £17.9bn, up 6% on the year.
And within that 44%, Google is almost everything. StatCounter says so, and so do UK searches: in our data "google ads" gets 165,000 searches a month, "microsoft advertising" and "bing ads" together 11,000. Fifteen to one.
How the auction works (and why you don't decide what a click costs)
Every time someone searches, Google runs an auction among the advertisers who've bought that word. The Google Ads Help page on Ad Rank lists six factors that decide who appears and in what position: your bid, the quality of your ads and landing page, the Ad Rank thresholds, the competitiveness of the auction, the context of the search and the expected impact of your ad assets.
In plain terms: the bid you set is a ceiling, not a price. The same page puts it like this: "How much you actually end up paying is often less".
You find out the real price afterwards. On the three Italian accounts we manage, between September 2025 and August 2026, a click on the Search Network cost an average of €1.81 (£1.53) and a conversion €117.80 (£99.83), on €115,984 of spend (£98,292 at the Bank of England rate for 8 October 2026, €1.18 = £1). On top of that, Google adds a 2% UK DST fee to ads served in the UK. The full bill, item by item, is in how much Google Ads costs; how paying per click works is in pay per click.
And if the word is contested?
Take "search engine marketing" itself. Anyone buying it on Google UK pays an estimated average CPC of £7.66 to appear in front of people looking up what SEM is, with top-of-page bids between £1.91 and £5.67 (Google Ads via DataForSEO, October 2026; CPCs converted from US dollars at the Bank of England rate for 8 October 2026, $1.3226 = £1). Five times the average of our three accounts.
The SEM toolbox (five stages, a free tool for each)
SEM tools are the software you need for the five jobs in a campaign: choosing keywords, watching competitors, building and editing ads, measuring what happens after the click, and reporting. There's a free tool for each one, almost always from Google or Microsoft. The paid ones earn their place as accounts grow.
| Stage | Free tool | UK searches a month | Paid tool | Starting price |
|---|---|---|---|---|
| Keywords | Keyword Planner (Google Ads) | 12,500 | Semrush | $139 a month (£105) |
| Competitors | Google Ads Transparency Center | 1,580 | SpyFu | $39 a month (£29) |
| Building and editing | Google Ads Editor, Microsoft Advertising import | 1,000 | Optmyzr | $209 a month (£158) |
| After the click | Google Analytics 4, Tag Manager, Microsoft Clarity | 38,800 | Hotjar, VWO and similar | varies |
| Reporting | Looker Studio | 12,100 | Paid connectors for Looker Studio | varies |
One row says more than the others: the Ads Transparency Center, which is free, gets 1,580 searches a month across its four spellings; SpyFu, which is paid, gets 1,600. In the UK the free competitor tool is as well known as the paid one. The free tool searched least is Google Ads Editor, at 1,000.
Keywords: Google's tool, and when it isn't enough
Keyword Planner sits inside your Google Ads account and costs nothing. The official guide describes it as the tool for finding keywords related to your business and seeing estimates of searches and cost to help you decide which ones to target. How to read its numbers is covered in how to use Google Keyword Planner.
It isn't enough when you want to know which keywords your competitors are spending on. For that you need third-party databases: the full comparison is in our guide to keyword research tools.
Competitors: the Ads Transparency Center, then SpyFu or Semrush
The Ads Transparency Center has been free since 29 March 2023, when Google launched it. You search for a competitor's name and see the ads it has run, in which region, in what format and the last date they were shown.
It doesn't tell you which keywords they appear on, or how much they spend. For that you need SpyFu or Semrush, and there's a detail most reviews skip: for the UK, SpyFu's history is the longer one, with data from June 2008 against January 2012 for Semrush. We checked it in SpyFu's and Semrush's own documentation, and it's all in Semrush vs SpyFu.
Building and editing: Google Ads Editor, and Optmyzr only past a certain size
Google Ads Editor is, in Google's words, a "no-cost, downloadable application" that lets you work on campaigns offline and make bulk changes. On an account with ten ad groups you'll barely need it; when you have to change a line of copy across two hundred ads, it saves you an afternoon.
Optmyzr is the next step: automation, checks and reporting across several ad accounts. It starts at $209 a month, about £158, with tiers set by the monthly ad spend you manage through it.
Does it make sense for a small business?
Do the sum. On a budget of £1,500 a month, Optmyzr on its own is 10.5% of what you spend on clicks. It's a tool for agencies and large accounts; below that, the time it saves is worth less than it costs. What budget makes sense for a small business is in Google Ads for small business, and the comparison of management software is on the page about PPC tools.
After the click: Analytics, Tag Manager and Clarity
An SEM campaign is judged on conversions, not clicks, and a conversion only exists if a piece of code on the site records it. Google Tag Manager installs the tracking code, Google Analytics shows what people arriving from the ads do.
Microsoft Clarity adds what the numbers don't say: heatmaps and session recordings, free. In the UK it gets 8,100 searches a month, exactly as many as "google keyword planner". If the page's conversion rate is low, that's where you see where people stop.
Reporting: Looker Studio
Looker Studio is Google's free dashboard tool that brings data from Google Ads, Analytics and Search Console into a single report. It connects to Google Ads through a free Google connector; for Microsoft Advertising you need a third-party connector, often a paid one. How we use it is in our guide to Looker Studio.
Microsoft Advertising: is it worth it in the UK? (6.08% of searches, campaigns imported from Google)
Microsoft Advertising is the platform that sells ads on Bing results and across the Microsoft network. In the UK, in September 2026, Bing had 6.08% of searches and Yahoo 1.32% according to StatCounter, against 91.39% for Google.
So it isn't worth bothering with?
That depends on what it costs to open. And it costs little: Microsoft Advertising imports "most supported campaigns, ads, targets, ad extensions, and other settings" from Google Ads, and the official documentation confirms the import can be scheduled daily, weekly or monthly. The campaigns stay in line without being rebuilt by hand.
For Macropix the ads run on Google Ads and on Bing too. Our position: switch Bing on once the Google campaigns are stable, never instead of them. With 6.08% of searches the volume stays small; but if the campaigns are imported, the extra work is close to zero.
Where budget gets wasted (the Macropix case, from €2,000 to €1,200 a month)
The most common way to waste money in SEM isn't picking the wrong keywords. It's raising the budget on the assumption that enquiries will rise in proportion.
We saw it on Macropix in spring 2026. Spend went up to €2,000 a month (about £1,695) and the cost per enquiry went up with it, so we brought it back to €1,200 (about £1,017). 2025 had closed with 328 enquiries at €39.44 each, the lowest cost since 2018.
Why doesn't more budget mean more enquiries?
Because ads don't create demand. The number of people searching for "ledwall" (LED wall) in Italy in a month is what it is: past a certain point the extra budget only buys worse clicks, on looser keywords or at weaker times of day. The same goes for any account: the right budget comes from the conversions you want, not from how much you're prepared to spend. At our average cost of €117.80 (£99.83) per conversion, ten enquiries a month need roughly £1,000 of clicks.
When it makes sense to switch ads on, and when to wait, is covered in when Google Ads is worth it.
Paying for clicks that don't bring enquiries?
You've just seen how raising a budget from €1,200 to €2,000 a month pushed up the cost of every enquiry. We review your Google Ads account, show you which part of the spend is buying worse clicks and work out the budget that supports the conversions you need.
Book a strategy consultationSEM and SEO together: the order depends on how soon you need a return (Sunscape)
SEM brings enquiries from day one; SEO brings them without an auction, but only after months. For Sunscape, which looks for land for solar and agrivoltaic plants in Italy, we started both at once: from January to August 2026 Google Ads brought in 144 enquiries on €15,451 of spend, €107 (about £91) each, while the site went from 46 to 195 organic clicks a month.
The ads covered the months when organic traffic wasn't there yet. That's why an SEM plan should never be drawn up on its own: the search terms that convert are the best starting list for SEO. How to make the two work together is in SEO and Google Ads together, and how to choose search by search in SEO or Google Ads.
Frequently asked questions
It depends on the definition you use. Early definitions combined organic and paid search; today, as Google says in its UK guide, the term typically refers to paid initiatives on search engines. SEO works on the organic results and has different tools and timescales.
No. SEM is the activity, Google Ads is the platform you do it with on Google. In the UK the two almost overlap because in September 2026 Google handled 91.39% of searches according to StatCounter, but SEM also includes Microsoft Advertising, which sells ads on Bing.
No. There's a free tool for every stage of a campaign: Keyword Planner, the Ads Transparency Center, Google Ads Editor, Google Analytics with Tag Manager, Microsoft Clarity and Looker Studio. Paid tools such as Semrush, SpyFu or Optmyzr are worth it when you want competitor data or manage many accounts.
It depends on what a conversion costs in your sector. On the three Italian accounts we manage, a Search Network conversion cost an average of 117.80 euros (about 100 pounds) between September 2025 and August 2026, so ten enquiries a month need roughly 1,000 pounds of clicks, plus the 2% UK DST fee and any management fee.
Yes, if your Google campaigns are already stable, because Microsoft Advertising imports them from Google Ads and can repeat the import daily, weekly or monthly. But Bing has 6.08% of UK searches, so the volume stays small and it shouldn't be switched on instead of Google.
No. Google only sells ad space and says, on its page about how Search works, that no one can buy better placement in organic results. The two channels help each other through data: the search terms that convert in your ads are a good starting point for SEO.
Where to start (and where SEM is heading)
In short:
SEM today means paid advertising on search engines, and in the UK that means Google Ads;
the auction sets the price, you only set the ceiling;
there's a free tool for every stage, and the Ads Transparency Center is searched for as often as SpyFu;
you add Bing by importing your campaigns, not rebuilding them;
the budget comes from conversions, not from what you can afford.
One number from our research isn't about Google or Bing. "Amazon ads" gets 5,400 searches a month in the UK, about half of "microsoft advertising" and "bing ads" put together. In Italy, where we ran the same check, Amazon came out ahead of Microsoft by four to one; in the UK Bing still holds second place in what people search for. The next contender may be an assistant rather than a marketplace: the UK was the first European market where ads inside ChatGPT answers went live, in June 2026, and we cover it in ChatGPT Ads. The rules of the auction, the ceiling and the budget worked out from conversions stay the same.
If you'd like us to set up and run the campaigns, that's the job of our Google Ads service.
Until next time!
