Every fit out company quotes in pounds per square foot, and every finance director thinks in people. The gap between those two habits is where most office budgets go wrong. A rate of £90 per square foot sounds precise until you realise nobody in the room knows whether the new office is 6,000 or 9,000 square feet, because the lease has not been signed and the space plan has not been drawn.
Budgeting per desk fixes this. You know your headcount. You know roughly how much you want it to grow. Everything else can be derived.
The arithmetic
London offices run at 80 to 120 square feet per person once meeting rooms, breakout, kitchen and circulation are included. Dense tech and sales floors sit at the bottom of that range, professional services with cellular offices at the top. Take 100 as the planning figure.
A Cat B fit out at standard to good specification costs £50 to £150 per square foot in London. Take £100 as the mid point. That gives £10,000 per person for construction before furniture. Furniture adds £1,500 to £4,000 per workstation depending on whether you are buying bench desks and task chairs or height adjustable desks and acoustic booths. Call it £2,500.
So the planning number is £12,500 per person, all in, before IT hardware, professional fees and VAT.
Three worked examples
A 20 person company taking a 2,000 square foot floor should plan for £250,000. In practice small spaces cost a little more per foot because the fixed items, the kitchen, the meeting room, the comms cabinet, are spread over fewer people. Budget £13,000 to £15,000 per head and use the small office fit out list, where the firms are set up for this size.
A 60 person firm at 6,000 square feet lands around £750,000. This is the heart of the mid market and where design and build contracts make most sense. Ask three firms from the office fit out companies list for a price against the same brief and you will usually see quotes within 15% of each other.
A 150 person headquarters at 15,000 square feet is £1.9m at mid specification and comfortably £3m if the finishes go premium. At this size an independent cost consultant earns their fee several times over.
What moves the number
Cellularisation is the biggest lever. Every enclosed room costs partitions, doors, glazing, its own lighting and its own mechanical balancing. Ten meeting rooms instead of five can add £100,000 on its own.
Base build condition is the second. If the landlord’s air conditioning cannot support your layout, or the floor boxes are in the wrong places, the mechanical and electrical line can double. Get a survey before you fix the budget, not after.
The third is the things left out of the square foot rate. Furniture, IT and AV, professional fees, building control, the landlord’s own fees and VAT are almost always separate. A quote that includes everything is rare and worth asking about explicitly.
Using the number
Take your headcount, multiply by £12,500, then adjust up for small spaces, premium finishes or a poor base build and down for open plan and a landlord that has already fitted a Cat A+ floor. That is your envelope. Give it to the firms you shortlist and ask each what they would do with it. The answers tell you more than the prices.
The full breakdown by size and specification is in the office refurbishment cost guide.
