We did this exercise for a Bath plumber last month. He had been on a 'free' website builder for two years and was about to renew. We sat down and added up the actual twelve-month cost across every line item, including opportunity cost. He moved to a custom build the next week.
The headline lie
Free website builders are not free. The free tier gets you a subdomain ('yourbusiness.platform.com'), the platform's logo on every page, no custom domain email, page speed at the floor of acceptable, and roughly zero meaningful SEO. The 'free' tier is a sales funnel into the paid tier, which is where the real costs start.
The 12-month TCO breakdown
For a typical UK trade business on the cheapest paid tier of a major builder, here is what you actually pay in twelve months:
- Builder subscription · £24/mo
- £288
- Custom domain
- £15
- Premium template (one-off)
- £75
- Booking integration plugin
- £180
- SEO plugin
- £120
- Email forwarding / professional email
- £60
- Visual TCO total
- £738
£738 sounds reasonable. It is not the real number.
The hidden costs nobody adds up
Opportunity cost · slow load times
Builder sites load in 3-5 seconds on mobile, typically. A custom build loads in under 1.5 seconds. Google's research shows every additional second of load time drops conversion by ~7%. For a trade getting 500 visits/month with 5% conversion to lead, slowing the site by 2 seconds costs you 7 leads/month. At £14k average job value and 15% close rate, that is around £14,000/year of leaked pipeline.
Opportunity cost · SEO ceiling
Builder sites cap out below custom builds on local SEO, typically. Less control over schema, slower Core Web Vitals, less granular page structure. The competitive trade with a custom site is going to outrank you for 'bathroom fitter Bath' even if your work is better. We see this pattern monthly.
Opportunity cost · the platform exit tax
When you outgrow the builder — and you will, around year two — migrating off it is painful. Content has to be re-exported, often by hand. URL structure breaks. SEO equity built up over two years gets partly lost. We have done this migration about a dozen times. It is at least a week of work that the client effectively pays for twice.
The real 12-month number
- Visible builder cost
- £738
- Conversion lost to slow speed
- £14,000
- SEO ceiling vs custom (estimated)
- £5,000-£10,000
- Exit migration cost (year 2)
- £1,500
- True 12-month TCO
- £21,000+
The custom build alternative
Our 24-hour template build is £500 plus £20/month hosting. £740 in year one, £240/year thereafter. Sub-1.5-second load. Full schema. Owned domain. No platform exit tax because there is no platform — it is your code on Vercel.
The maths is not close. The reason 'free' builders persist is that the cost is hidden and gradual. The reason custom builds win is that the cost is visible and finite.
If a tool costs you £20 a month visibly and £1,200 a month invisibly, it is not a £20 tool.
Seb Planchais
If you are on a builder right now and trying to decide whether to migrate, the question is not 'can I afford to.' The question is whether you can afford another twelve months of leaking the difference.