---
title: "How to Calculate Cost Per Lead and ROI When Buying Leads: A UK Tradesperson's Guide"
description: "Learn how to calculate ROI on leads and cost per lead as a UK tradesperson. Use our simple formulas and break-even calculator to know if leads are profitable."
author: "James"
author_title: "Head of Content"
author_url: "https://blog.referr.co.uk/author/james"
date: 2026-11-14T09:00:08.278Z
language: "en"
category: "Lead Generation"
tags: ["ROI on leads for UK tradespeople", "cost per lead calculation", "lead generation ROI formula", "break-even cost per lead", "qualified leads vs cheap leads"]
canonical: "https://blog.referr.co.uk/how-to-calculate-cost-per-lead-and-roi-when-buying-leads-a-u"
---

# How to Calculate Cost Per Lead and ROI When Buying Leads: A UK Tradesperson's Guide

A £25 lead that turns into a £400 job isn't automatically good value — it depends on how many quotes you had to send out to get there. Cost per lead (CPL) and return on investment (ROI) are the two numbers that tell you whether a lead supplier is making you money or quietly draining your bank account.

This guide gives you the exact formulas, worked examples for common UK trades, and a method you can run on your phone between jobs — no spreadsheet, no marketing degree required.

## The Two Formulas Every Tradesperson Needs

Everything here comes back to two calculations.

**Cost Per Lead:** Total Spend ÷ Number of Leads Generated.
Spend £300 on a lead package and get 12 leads, your CPL is £25.

**Return on Investment:** (Revenue from Leads − Cost of Leads) ÷ Cost of Leads × 100.

Here's a worked example with real numbers. A heating engineer spends £1,200 on leads in a month and books £4,000 worth of jobs from them. That's (£4,000 − £1,200) ÷ £1,200 × 100 = 233% ROI — for every £1 spent, they got back £3.33. A lurvodigital analysis of broker lead generation puts well-managed campaigns in the 200–500% ROI range, which gives you a rough benchmark to aim for.

> 💡 If you're VAT registered, strip VAT out of your job revenue before running the ROI sum. A £1,200 job might only be £1,000 in real income once HMRC takes its 20% — and that changes whether a lead was actually worth what you paid for it.

## Your Break-Even CPL: The Phone Calculator Method

Here's the shortcut version, built for standing in a van tapping it into your phone: **Break-Even CPL = Average Profit Per Job × Your Quote-to-Job Close Rate.**

Know those two numbers for your trade, and you instantly know the ceiling price you can pay per lead before you're losing money.

| Trade | Avg. profit per job | Typical close rate | Break-even CPL |
|---|---|---|---|
| Electrician | £180 | 25% | £45 |
| Plumber | £150 | 30% | £45 |
| Roofer | £800 | 15% | £120 |
| Mechanic | £90 | 40% | £36 |
| Accountant (first-year client) | £600 | 20% | £120 |

Don't pay anywhere near your break-even figure — that's your absolute ceiling, not your target. Aim for 40–50% of it, leaving room for profit, overheads, and the leads that simply don't answer the phone. For the [electrician](/b/referr/lead-generation-for-electricians-in-the-uk-how-to-win-more-r) above, that means a target CPL around £18–£22, not £45.

One thing the industry rarely mentions: this table understates the real picture for trades with repeat custom. A [plumber](/b/referr/lead-generation-for-plumbers-and-heating-engineers-in-the--2)'s £150 profit figure is just the first job — add a boiler service contract or referral down the line and the true lifetime value might be £400+. Accountants and mortgage brokers especially should calculate ROI against client lifetime value, not the first invoice.

## Why a Cheap Lead Can Secretly Cost You More

A £3 lead sounds better than a £150 lead. It usually isn't.

Research from LaGrowthMachine on lead quality found a $150 qualified lead converting at 20% produces a customer acquisition cost of $750, while a $3 unqualified lead converting at just 0.5% actually costs $600 per customer once you account for the volume needed to land one job. The cheap lead *looks* cheaper on paper but costs more once you factor in [conversion rate](/b/referr/referr-vs-bark-which-lead-marketplace-is-better-for-uk-trade).

Then there's the time cost nobody puts in a spreadsheet. The same research points to $200–400 in wasted sales and quoting time when tradespeople chase low-quality, unqualified leads — time spent driving to quote jobs that were never serious, or calling numbers that don't pick up.

The lesson: optimise for cost per *qualified* lead, not the lowest raw CPL on the page. A supplier charging £40 for leads that are genuinely ready to book beats one charging £15 for leads who were "just getting some quotes for next year."

## Exclusive vs Shared Leads: Same Price, Different Outcome

This is the biggest hidden variable in lead buying, and it's rarely explained properly.

Say two suppliers both sell you a lead at £30 CPL. Supplier A sells it to you exclusively. Supplier B sells the same lead to four other tradespeople at the same time. On paper, identical CPL. In reality, wildly different ROI.

- **Exclusive lead, 30% close rate:** effective cost per job = £30 ÷ 0.30 = £100.
- **Shared lead (5 ways), close rate drops to roughly 8% because you're now one of five quotes:** effective cost per job = £30 ÷ 0.08 = £375.

Shared leads can still work — they're usually cheaper upfront and fine for quick, high-volume trades like locksmiths or man-and-van jobs. But for anything with a longer sales cycle — roofing, extensions, kitchen fitting — exclusivity is usually worth the premium. Always ask a supplier directly: is this lead sold to me alone, or to a panel of competitors?

---

## Seasonality: Why Your Numbers Swing Through the Year

CPL and close rate aren't fixed — they move with the British weather and calendar, and treating them as static numbers will throw your whole ROI calculation off.

- **Boiler and heating engineers:** demand and CPL both spike November to February. Competition for leads rises, so cost per lead climbs, but close rates often rise too because homeowners with a dead boiler in January aren't shopping around for long.
- **Roofers:** demand is reactive — storm damage drives sudden local spikes in cheap, high-converting leads, while calm summer months mean paying more for fewer enquiries.
- **Landscapers and garden trades:** March to June is peak season. CPL rises with demand, but so does job value, as people plan bigger projects for summer use.

The practical fix: don't judge a supplier on one month's numbers. Set a separate break-even CPL for peak and off-peak season, and expect to pay more per lead in your busy months while accepting thinner margins — that's where the volume comes from.

## Spotting "Guaranteed ROI" Red Flags

If a lead supplier promises "guaranteed 10x ROI" or a specific monthly revenue figure, ask to see the methodology before you believe a word of it.

Some promotional material aimed at UK tradespeople claims returns of £10,000–£12,000 a month in revenue, or 10x ROI, from an average spend. These figures come from self-published marketing posts, not independently verified data — and ROI depends entirely on your close rate, average job value, and trade, none of which a supplier can know in advance for your business.

> 🚩 Commission-based or "pay only for leads that convert" models can be genuinely useful — but ask exactly how "converted" is defined, who verifies it, and what happens to leads you quoted but didn't win. Vague answers are the red flag, not the pricing model itself.

Pricing across the market genuinely varies: posts in UK trade discussion groups show costs ranging from around £89 a year for a basic directory listing up to £349 a month for a dedicated pay-per-lead platform. Neither end is automatically better — judge every option on CPL and ROI, not sticker price.

## Monthly Tracking Habits for Sole Traders

You don't need a CRM to track this properly. A notes app, a notebook, or a simple phone spreadsheet does the job.

Each month, log four things per lead: the source (Checkatrade, a pay-per-lead marketplace, Google Ads, a Facebook referral), the cost, the outcome (won, lost, no response), and the job value if won. At month-end, total it up by source and work out CPL and ROI separately for each channel — not as one blended number.

This is where most sole traders go wrong: they judge "leads" as one category instead of tracking by channel. A directory might deliver cheap but low-converting leads while a pay-per-lead marketplace delivers fewer but better-qualified ones. Without splitting them out, you can't see which is actually earning you money — and you end up cutting the good channel because the bad one is dragging the average down.

## Frequently Asked Questions

### How many leads should I buy before judging a supplier's ROI?

Give a new supplier at least 10–15 leads or one full month before drawing conclusions, since small sample sizes can make a decent supplier look bad or a poor one look lucky. If close rate and CPL still look off after that volume, it's a fair test to walk away or renegotiate.

### Should I count VAT when calculating ROI on leads?

Yes, if you're VAT registered, calculate ROI using net revenue (excluding the 20% VAT you'll pay to HMRC), not the gross invoice total. Skipping this step makes every lead look more profitable than it actually is.

### Is a cheaper lead always worse value than an expensive one?

Not always, but cheap leads need checking against close rate and wasted quoting time, not just price. A £10 lead converting at 5% can easily cost more per customer than a £40 lead converting at 25% once you do the maths.

### How do exclusive leads compare to shared leads for ROI?

Exclusive leads usually produce a lower effective cost per job because you're not competing with other quotes, even though the upfront CPL is often higher. Shared leads can still work for fast-turnaround trades but tend to perform worse for jobs where customers compare multiple quotes.

### How often should I re-check my break-even CPL?

Review it at least twice a year, and separately for peak and off-peak season if your trade is weather- or season-dependent. Job values, material costs, and close rates all shift over time, so a break-even figure calculated last year may no longer reflect what you can actually afford to pay today.

Work out your break-even CPL for your trade this week, track every lead against it for a month, and you'll know within 30 days whether your current supplier is earning its keep or quietly costing you money.

**Ready to buy or sell leads in the UK?**

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[Get started on Referr](https://referr.co.uk)

## Written by

**[James](https://blog.referr.co.uk/author/james)**, Head of Content