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Forecast your own auction
Start by throwing away the benchmark tables. There is no published, independent UK cost-per-click benchmark broken down by trade. The “average CPC by industry” charts that circulate are aggregations of one software vendor's own customer base, usually weighted heavily towards the United States, and there is no way for you to check whether the sample resembles your town at all. Using one to set a budget for a plastering firm in Chesterfield is astrology with decimal places.
The auction you are actually buying into is small, local and knowable. Pull the forecast yourself. It takes about twenty minutes and you do not have to spend anything to do it.
- Create a Google Ads account and skip past the guided setup into expert mode. You can reach Keyword Planner without a live campaign.
- Choose Get search volume and forecasts, not the ideas tool. Paste in fifteen to twenty-five terms you would genuinely want to appear for, written the way a customer types them, not the way you describe the trade.
- Set the location to the towns you actually serve. Not the county, not the United Kingdom. The difference between “Derbyshire” and “Chesterfield plus Dronfield plus Clay Cross” will change every number on the screen.
- Set the language to English and the date range to the next thirty days, then drag the maximum bid slider. You are not looking for one figure, you are looking at the shape of the curve: where extra pence stop buying meaningfully more clicks.
- Write down three numbers at the bid you would realistically pay: monthly clicks, average cost per click, and the impressions available.
Treat it as an order of magnitude, not a quotation. Forecasts assume you can hold the ad rank they model, and a brand new account with no conversion history and an unproven landing page usually pays above forecast for its first few weeks while quality signals settle. If the forecast says £4.20, plan on paying five-something in month one. What the forecast is genuinely reliable for is the thing you cannot guess: whether there are two hundred searches a month in your patch or two thousand.
Work backwards from jobs, not forwards from budget
Most owners approach this from the wrong end. They pick a number that feels tolerable, spend it, and then try to decide afterwards whether the result was good. Reverse it. Decide how many extra jobs you want next month and let the arithmetic hand you the budget.
There are four conversion steps between a click and an invoice, and almost everybody forgets the second one.
- Clicks to enquiries. Your landing page conversion rate. For a focused trade page with a phone number that works, mid-single figures to the low teens is the normal territory. If yours is under three per cent the page is the problem, not the budget.
- Enquiries to quotes. The forgotten step. Some proportion of enquiries are out of area, out of scope, out of budget or never answer the phone back. Most trade firms quote somewhere between six and eight of every ten enquiries they receive, and a few quote half.
- Quotes to jobs. Your close rate, which you probably already know within five points.
- Jobs to money. Average job value, and if domestic and commercial differ wildly, two separate calculations.
Suppose a bathroom fitter wants six extra installations a month, closes one quote in three, quotes seven of every ten enquiries and converts eight per cent of landing page visits. Six jobs needs eighteen quotes, which needs about twenty-six enquiries, which needs roughly three hundred and twenty-five clicks. At a forecast cost per click of £3.60 that is about £1,170 a month of ad spend. That is a defensible number. It came from his own close rate and his own auction, and every assumption in it is one he can go and check.
Run the same chain with pessimistic inputs before you commit. Drop the conversion rate to five per cent and raise the click cost twenty per cent and see whether the answer is still affordable. If the pessimistic version is ruinous, the honest conclusion is that search is not the right first channel, and we would rather tell you that on the phone than four months into an engagement. Our methodology page sets out how we run that check before anyone signs anything.
The floor below which an account cannot learn
Budgets fail at the bottom end for a mechanical reason rather than a philosophical one. Optimisation needs events to optimise on.
Two thresholds matter. Below roughly fifteen to twenty conversions a month you cannot tell a real change in performance from ordinary week-to-week noise, so every decision you make is a coin toss dressed up as analysis. Below roughly thirty conversions a month, Google's Target CPA and Target ROAS strategies have too little to model and tend to behave erratically, throttling delivery or chasing whichever cheap conversion type they can find. On thin volume, manual bidding or a plain maximise-clicks strategy with tight keywords and a hard bid cap is usually steadier than automation.
There is a second, cruder floor. Google can spend up to twice your daily budget on an individual day, balancing back over the month so you are never charged more than your daily figure multiplied by 30.4. But if your daily budget is smaller than two or three clicks, your ads stop showing early in the day, you miss whole dayparts, and the data you collect is skewed towards whatever time of morning your money ran out. As a rule of thumb, set the daily budget high enough to buy at least five clicks. At a forecast click cost of £6 that is £30 a day before you have decided anything else.
This is why the honest answer to “can I test it with a couple of hundred pounds?” is usually no. Not because small budgets are morally wrong, but because a hundred and fifty clicks spread over a month produces perhaps eight enquiries, and eight enquiries cannot tell you anything you did not already believe.
Dividing the money between campaigns
Once you have a total, the next decision matters more than the total does. Put every campaign on its own budget. Shared budgets look tidy and behave badly: the campaign with the cheapest clicks and the highest volume will drain the pot by lunchtime, and that is almost never the campaign attached to your best work.
| Campaign | Typical share | Why it gets that share | What would change it |
|---|---|---|---|
| Urgent / same-day work | 20–40% | Converts fastest and needs headroom on the days demand spikes | Cut it to near zero if calls go to voicemail |
| Core service, highest margin | 35–50% | The work you actually want more of, and the work your proof supports | Raise it when impression share lost to budget climbs |
| Secondary services | 10–20% | Fills capacity and tells you which service to build a page for next | Pause entirely when the diary is full |
| Brand defence | 2–5% | Cheap, and only necessary if somebody is bidding on your name | Check the auction insights report before funding it at all |
| Remarketing | 0–10% | Only worth it where the decision takes weeks — extensions, re-roofs, full rewires | Skip for emergency-led trades |
Two rules make the split hold. Never let domestic and commercial share a campaign, because the cheaper clicks win the budget and the expensive enquiry never sees an ad. And set separate budgets before you set separate bids — a budget cap is a blunt instrument that always works, while bid adjustments are a fine instrument that often does not.
Reading the pacing signals
The columns that tell you whether your budget is the right size are hidden in the campaign view and almost nobody enables them. Add Search impression share, Search lost IS (budget) and Search lost IS (rank).
The interpretation is simple and it is the closest thing to a rule in this whole discipline. If lost impression share to budget is above about twenty per cent on a campaign whose cost per enquiry is already below your target, you are turning away profitable work to save money. Raise the budget. If lost impression share to rank is the large number instead, more money will not help; your ads are not eligible often enough because of bid, relevance or landing page quality, and the fix is in the account rather than the bank.
When you do raise it, move in increments of twenty to thirty per cent and leave a week between changes. Automated bidding treats a large sudden budget change as a new problem and re-paces around it, which produces a fortnight of noise exactly when you are trying to read a result. If a campaign is consistently underspending its budget, that is usually a targeting problem — keywords too narrow, geography too tight, negatives too aggressive — rather than proof that demand does not exist.
The ceiling nobody warns you about
Paid search is the biggest single line in UK digital advertising. The IAB UK Digital Adspend 2025 study puts total UK digital ad spend at £40.5bn, of which paid search accounts for £17.9bn, about forty-four per cent. That scale is the reason the auction is crowded, and it is also the reason “spend more than the other firm” is not a plan.
More to the point, search demand in one town is finite. There are only so many people typing your service into a phone this month, and once you are appearing for most of those searches, additional budget buys progressively worse traffic: looser matches, wider radius, lower intent. You will see it as a rising cost per enquiry with no corresponding rise in enquiry quality.
When you hit that, there are three sensible moves and one bad one. The sensible ones are widening the geography into the next ring of towns, adding a service you can genuinely deliver, or moving the marginal money into channels that create demand rather than harvest it — paid social for the considered, higher-value jobs, and organic search so that next year's enquiries cost less than this year's. The bad move is to keep raising the search budget and quietly accept the worse average.
When to change the number
- Monthly. Compare cost per enquiry against your own job-back calculation, not against last month. The question is never “did it go up?” but “is it still under what an enquiry is worth to me?”
- Whenever impression share lost to budget passes twenty per cent on a profitable campaign, raise that campaign's budget by a quarter.
- Whenever your diary fills, cut the secondary service campaigns first and leave the core one alone. Turning everything off for a month costs you the momentum and the conversion history.
- Before your season turns. Budget changes take a couple of weeks to settle, so move the money before demand moves, not after.
- Never on a bad week. Weekly variance in a trade account is enormous. Two quiet weeks is weather; six is a trend.
If you want the definitions behind any of the terms above, the glossary covers them in plain English, and the benchmarks page sets out which figures we are willing to stand behind and where they came from. If you would rather someone built the forecast with you, that is what we do — and if the arithmetic says no, we will say so on the first call.
Rather have someone else do this?We run exactly this for trade and construction firms across the UK. Call and we will tell you what is realistic in your area, including when the answer is that it is not worth it.
Call 07443 392243WhatsAppCommon questions
Is there a minimum budget Google requires?
No. Google imposes no minimum. The practical floor comes from your own auction: you need a daily budget that buys at least a handful of clicks, and enough monthly conversions to tell signal from noise. In an expensive urban auction that lands far higher than in a market town, which is why the forecast has to come first.
Should the budget include the agency fee?
Keep them separate in your head and separate on the invoice. Ad spend should go to Google on your own card, and management should be billed on its own line. When the two are combined into one figure you lose the ability to check what was actually spent in the auction, and every performance calculation becomes unverifiable.
How long should I commit for before judging it?
Ninety days is the honest minimum for a new account. The first month buys data at a premium while quality signals settle, the second is spent cutting waste, and the third is the first month that represents steady-state performance. Judging at four weeks means judging the learning period.
What if my competitors clearly spend far more?
Budget is not the only lever and often not the decisive one. Relevance lowers what you pay for the same position, tight geography concentrates a small budget where it converts, and a page that answers the search converts traffic your competitor wasted. A smaller, sharper account regularly beats a larger, lazier one.
Can I just start small and scale up?
You can scale up, but starting below the learning floor tends to produce three months of ambiguous data and a decision made on a feeling. It is usually better to fund one service in one town properly than four services across a county thinly.