Ask three contractors what a London office fit-out costs per square foot and you will get three numbers that do not overlap. That is not because two of them are wrong. It is because a per-square-foot rate is a summary of dozens of decisions nobody has made yet, and the person quoting has silently made them for you.
Here is what the range actually looks like in 2026, where the money goes inside it, and what moves it.
The headline range, and why it is so wide
A Cat B fit-out — the part that turns a bare, serviced floor into an office your staff can work in — runs roughly £65 to £175 per square foot net in London. On a 2,500 sq ft floor, that is £162,500 at the bottom and £437,500 at the top for what most people describe in the same three words.
It is more useful to think of it as three bands than as one range:
- Essential, £65–£80/sq ft. Open plan, a small number of meeting rooms, a modest tea point, carpet tile, standard lighting. Perfectly good. Nothing bespoke.
- Balanced, £95–£120/sq ft. More cellular space, glazed partitions, better acoustics, a proper tea point, some joinery made to fit rather than bought off a page.
- Signature, £135–£175/sq ft. Reception joinery, specialist finishes, considered lighting design, high-end AV, acoustic treatment that has been modelled rather than guessed.
For context, Cat A — the landlord’s base build, before any of the above — is roughly £35 to £65 per square foot. And at the very top of the market, Turner & Townsend’s 2026 guidance puts high-specification London fit-out around £409 per square foot. If someone quotes you a headline figure, the first question is which of those layers it includes.
Where the money goes
This is the part that makes the range legible. Take a mid-band job at £107.50/sq ft on 2,500 sq ft — £268,750 — and it breaks down roughly like this:
- Builders’ work — around 41%. Partitions, ceilings, floors, joinery, decoration. The biggest single block, and the one your design decisions move most.
- Mechanical and electrical — around 25%. Power, data containment, lighting, and the heating and cooling alterations. Largely fixed by the building, not by your taste.
- Security, IT and AV — around 13%. Access control, cabling, screens, room booking.
- Furniture and FF&E — around 12%. Frequently not in the contractor’s number at all. Check.
- Professional fees — around 9%. Design, project management, building control, statutory approvals.
Two things fall out of that split. First, when a client says the cost needs to come down, the honest answer almost always sits in builders’ work, because M&E is dictated by the building. Second, roughly a quarter of the total is not construction at all — it is furniture and fees, and those are the lines most often quietly missing from a comparison.
The two costs that are not in the rate
Dilapidations. At the end of a lease you are usually obliged to put the space back roughly as you found it. Reinstatement typically runs £15 to £35 per square foot, and it is not in anybody’s fit-out quote. On a 2,500 sq ft floor that is £37,500 to £87,500 waiting at the far end of a five-year term. Read the schedule of condition before you design anything, because some of what you are about to build, you will later pay to remove.
Contingency. Budget 5–10% on a modern building and 10–20% on older stock. That second number is not pessimism. It is the recognition that in a 1930s building nobody knows what is above the ceiling until the ceiling is down, and the surprises are rarely cheap.
What actually moves the number
Not the postcode. Building condition varies far more than location does, and a tired 1960s block in a cheaper part of town will cost more to fit out than a 2018 building somewhere expensive.
Four things move it most.
The building’s services. If the existing heating and cooling can be adapted, M&E stays near a quarter of the budget. If it cannot, that line can double and it takes the headline rate with it.
How much you cellularise. Every additional meeting room is partitions, a door, a light circuit, an air path and an acoustic problem. Going from four rooms to eight on the same floor plate is not a layout change; it is a cost change. And it is worth knowing that partition acoustic performance on a drawing — Rw 45 dB, say — is not what you get on site, because sound flanks over the partition head through the ceiling void and under it through the raised floor. Specifying a better partition without sealing those paths buys you very little.
The floor plate itself. A long, narrow floor with the core in an awkward position forces circulation you would not otherwise build, and circulation is square footage you pay to fit out and never occupy. Two buildings advertised at the same area can differ by ten per cent in usable space once the layout is drawn, which moves the cost per usable square foot without changing the headline rate at all.
Programme. Compressed programmes cost money in overtime, in out-of-hours working where the landlord requires it, and in the premium you pay for materials that have to arrive next week rather than in six weeks. A fit-out that has to be finished before a lease expiry is a more expensive fit-out than the same job with an extra month.
What to ask before you sign
Four questions, and they take about ten minutes.
- What is excluded? Furniture, IT hardware, AV, professional fees, landlord’s approval costs and dilapidations are the usual absentees. Get it in writing.
- What is the contingency, and who holds it? If the answer is that there isn’t one, the number in front of you is not a budget.
- Where does the price change? Ask which items are provisional sums or rates rather than fixed. That is where a low headline number becomes a high final one.
- Can I see the cost broken into the five blocks above? A contractor who cannot split their own number into builders’ work, M&E, security and IT, FF&E and fees has not built it up properly.
A per-square-foot rate is a summary, not a price. It is genuinely useful for testing whether you are in the right order of magnitude before spending money on design, and misleading the moment it is treated as a quote. If you want the full breakdown with the band-by-band arithmetic, we publish what an office fit-out costs per square foot in London in detail, including the element splits and the compliance costs most schedules leave out.
One disclosure, because it affects how you should read the partitioning section above: we supply and install glazed partitions, so we profit directly from that line. Weigh it accordingly.
Vladimir Castravet is the founder of 2VP Design & Build, a London design-and-build contractor specialising in commercial office fit-out, microcement, bespoke joinery and windows.
