The number everyone quotes, and why it stopped working
For twenty years the planning rule was 150 to 250 usable square feet per employee, and it was close enough to sign a lease on.
That rule assumed everyone came in every day and everyone had an assigned desk. Neither holds now. A company with 200 employees and 40 percent average attendance does not need 200 desks, but it also cannot survive on 80, because attendance is not spread evenly across the week.
Sizing on the average is the most common and most expensive mistake in office space planning. You end up with a space that works Monday and Friday and fails every Tuesday through Thursday, which is exactly when your people form their opinion of the office.
Start with the peak day, not headcount
The planning question is not how many employees you have. It is how many are in the building on your busiest realistic day, and what they are doing while they are there.
Pull badge data, room booking data, or wifi counts for the last six months. Find the 90th percentile day, not the mean. That is your design number.
Then answer four things:
- ›Which roles need assigned seats because of equipment, files, or confidentiality?
- ›Which teams come in together, and on which days?
- ›How many people are on video calls at their desk at any given moment?
- ›What is the meeting load, in rooms of what size?
A 200-person company with a 120-person peak, 30 assigned seats, and heavy call volume needs a different plan than a 200-person company with the same peak and no calls. The square footage might be identical. The furniture is not.
Square footage by space type
Rough planning allowances for New England commercial space. Use these to sanity-check a test fit, not to write a lease.
- ›Open workstation, benching: 25 to 40 square feet per seat
- ›Open workstation, panel system with storage: 48 to 64 square feet per seat
- ›Private office: 100 to 150 square feet
- ›Executive office: 150 to 250 square feet
- ›Phone booth or focus pod: 25 to 35 square feet each
- ›Huddle room, 4 people: 100 to 150 square feet
- ›Conference room, 8 people: 250 to 300 square feet
- ›Boardroom, 16 people: 450 to 600 square feet
- ›Training room: 20 to 25 square feet per seat
- ›Cafe or pantry: 12 to 20 square feet per peak occupant
- ›Reception: 150 to 300 square feet
Add 25 to 35 percent on top of the sum for circulation, core, and support. That is the gap between usable and rentable square feet, and it is where early budgets usually go wrong.
Density has a floor
You can shrink square feet per person a long way before the space fails. Then it fails quickly.
Egress and accessibility set the hard limit. Aisle widths, door clearances, and accessible routes are code, not preference. A layout that pencils on paper and violates clearance gets caught at inspection, after the furniture is installed.
Acoustics set the practical limit. Benching at 25 square feet per seat with no screens, no absorption, and heavy call volume produces a room nobody will work in. Going dense means budgeting for acoustic panels, screens, and enough enclosed rooms to absorb the calls. One enclosed one-person space per 10 to 15 peak occupants is a reasonable starting ratio.
Storage gets forgotten. Shared seating removes the pedestal file, and that storage has to reappear somewhere, usually as lockers. Lockers need floor area and a circulation path in front of them.
Plan where the extra 15 people sit on the day nobody predicted. Cafe seating with power is the cheapest answer.
How to test a plan before you sign the lease
Take the test fit and walk it against real Tuesday behavior.
Count the seats and compare to your 90th percentile day. Count the enclosed one-person rooms and compare to your call volume. Count meeting room seats and compare to your booking data by room size, because most companies are short on four-person rooms and long on twelve-person rooms.
Check power. Every shared seat needs a working outlet and a monitor connection, or people will not sit there twice.
Check the path from the elevator to the coffee. If that walk passes through somebody's focused work, you have a layout problem that furniture will not fix.
Then price it. A space plan with no furniture budget attached is half a plan. We render both together, in 3D, in under three business days, because the layout decision and the money decision are the same decision.
