What a fractional CTO actually costs in the UK

Enough people in this category now publish a fractional CTO cost that “it depends” has stopped being an acceptable answer. Here’s the range, where it comes from, and where I sit in it.

The number comes first here, then what it buys. Where a figure is somebody else’s, the source and the date I checked it sit next to it, and my own rates are on the same page as theirs.

The going rate

Three models are common in the UK for fractional CTO work.

Day rate. £800 to £1,600 a day. At the lower end you’re buying a senior engineer who also advises. At the upper end you’re buying someone who has run a technology function and will make decisions you can’t make yourself. This band is what I see quoted and paid.

Monthly retainer. £3,000 to £8,000 a month for SME and startup engagements, with a cluster around £4,000 to £6,000. That band carries the same caveat as the day rate. Some providers do put it on the page. fcto.uk lists an advisory tier at £3,000 to £5,000 a month and an active CPTO tier at £8,000 to £12,000, excluding VAT. Hurricane Studio publishes $5,000 to $30,000 a month and says most engagements land between $10,000 and $20,000. Both checked August 2026. A retainer buys a cadence: standing ownership of the technical direction, and someone reachable when something breaks.

Productised or subscription. A smaller group sell “unlimited technical input” for a flat monthly fee, sometimes paid in equity or revenue share. You’re buying availability, which works when the need is unpredictable and badly when it’s heavy. I don’t sell one.

For comparison, hiring the role outright. Robert Half’s 2026 UK salary data puts a CTO at £120,000 at the 25th percentile, £160,500 at the median and £201,500 at the 75th, checked August 2026. On top of those sit equity, employer’s national insurance, pension, recruitment fees, and three to six months to fill the seat.

What I charge

I’ve just spent a section on what other people cost, so here are mine.

The diagnostic is £7,500. Two weeks, fixed, and the price doesn’t move with the size of your business. It’s the one price on this page that isn’t a rate, because it’s priced on the outcome.

Day rate is £1,000. One number, because a band turns every conversation into a negotiation about which end you’re at. It sits in the lower half of the market band above, on purpose. What I sell is a decision I’ll stand behind, and the diagnostic and the retainers put a fixed price on that.

Retainers start at £2,000 a month for a support retainer of two days a month, for a system that’s live and needs looking after. £4,000 a month buys one day a week and £7,500 a month buys two. The support retainer comes out at £1,000 a day. There are 4.33 working weeks in a month (52 over 12, if you’re checking), so the weekly ones come out at £924 and £866 a day. All three sit inside the band above, and the rate falls as the commitment rises. Ask anyone quoting you a retainer to show you the same sum.

The weekly retainers cost less a day than my £1,000 day rate because you’re committing, and the support retainer costs the same because two days a month is too little to discount. A retainer also reserves a slot I can’t sell to anyone else, and it buys you being able to reach me between the scheduled days, by email or chat, for a decision that can’t wait. I aim for a considered reply within one working day on a weekly retainer and two working days on the support retainer. Those are targets I work to, not a guaranteed service level, and as-needed work carries none.

No minimum term. Retainers run month to month, with 30 days’ notice either way. I’d rather you stayed because the arrangement is working than because you signed something in March.

More than two days a week is possible but I don’t publish a price for it, because three days is most of one person’s week.

If you need less than two days a month, I work at my £1,000 day rate as and when: booked in half days and invoiced for what’s used. Nothing is reserved, so there’s no reply promise.

Build work is quoted, never rated. A brief I can price has four things in it, and the diagnostic page lists them in full: what done looks like, representative data, where the code lives, and one person who can decide. Hand me those and the quote is free, and you don’t need the diagnostic at all. Hand me three of them and you get a range with the assumptions written next to it, and closing those is what the diagnostic does. I won’t put a number on a build I haven’t seen the shape of, because I’d be guessing.

All prices exclude VAT. I’m VAT registered, so VAT is added to every invoice. Whether you can reclaim it depends on your own business, and your accountant will know.

What the range is really measuring

The spread between £800 and £1,600 has less to do with quality than with how much of the decision you’re handing over. The mistake I see most is paying a rate that buys judgement and then briefing the person as if they were an extra pair of hands.

Ask a question they don’t already know the answer to, and see whether you get a question back or an opinion.

What it isn’t buying

Throughput. A fractional CTO two days a week doesn’t produce two days a week of code plus the leadership. If you need volume you need engineers, and a fractional CTO is the person who tells you how many and what shape.

Availability in a crisis, unless you’ve paid for it explicitly. If they have four clients, they have four crises, and yours isn’t always first.

Institutional memory. A full-time CTO accumulates context about your business every day for years. A fractional one accumulates it in the hours you pay for. You can manage that gap, but only by writing things down.

The mistake that costs most

I’ve watched a business spend serious money on a system that worked exactly as specified and solved a problem it didn’t have. The specification had been written before anyone established what the real constraint was.

That’s why the first thing I sell is a fixed-price diagnostic, two weeks, £7,500: I triage what’s costing you, establish why from your own systems, take the riskiest assumption in the plan and test it, and then we decide what to build and what it costs.

The third step is one of two things, agreed before you commit: software that runs, with the test it had to pass, or an experiment on your own data with the pass mark set first. The diagnostic page has both in full, and there’s a worked illustration of the whole deliverable, written for a business that doesn’t exist.

It’s priced as its own piece of work. And it’s fixed because of what a day rate would do to my incentives: if I were paid by the day to decide what to build, I’d earn more by taking longer. On a fixed fee I want the right answer and then I want to be finished.

How to work out what you should pay

Stop benchmarking the rate. Work backwards from what a wrong decision costs you.

If the decision is worth £30,000, say a small internal tool or a choice between two vendors, a few days of senior input is proportionate and a long retainer isn’t.

At £300,000, a platform rebuild, say, or an architecture you’ll live with for five years, the gap between good advice and adequate advice is worth many multiples of the fee. Choosing on rate there will cost you more than it saves.

And when the decision is the company itself, the technical direction of a product you’re raising money against, you aren’t buying advice any more. You need someone who’ll own the outcome with you, and that’s a different purchase from a rate.