The band, not the desk, sets the count
At the defaults a desk is 27 inches deep. The band it lives in is 10 feet 6 inches, because two desks sit back to back and each needs 36 inches behind it for a chair and for getting out of that chair. Add a 40 inch aisle and the pitch from one band to the next is 13 feet 10 inches, of which the actual worktop is 54 inches — 33 percent.
That ratio is why trimming the desk is the wrong lever. Take three inches off the depth and the pitch falls by six, which is nowhere near a whole extra band. Share a spine instead of standing every row alone and the defaults go from 32 desks to 36 on the same floor, because two rows of desks now share one band rather than needing two.
Turn the rows and count again
Band pitch is a divisor and floor dimensions rarely divide by it neatly. At the defaults, running the rows along the 78 foot side gives a 45.3 by 35 foot rectangle: nine desks to a row, but only two bands, because three bands need 458 inches and the depth is 420. Running them along the 42 foot side gives 22.3 by 71 feet: only four desks to a row, but five bands fit. Forty desks against thirty-six, on a plate that has not changed at all.
Nothing about the furniture or the budget moves; the rows simply divide into one dimension with less waste than the other. The results table shows both so the choice is explicit rather than inherited from whichever way the first sketch happened to be drawn. It is worth checking again after the meeting rooms move, because taking the shared band off one end changes which dimension the desks have left.
The leftover strip is the tell
Watch the unused depth line. At the defaults the chosen orientation leaves 14 inches of depth doing nothing, and it is 12 feet 8 inches short of another band, so no amount of tidying recovers it. What that slack does mean is that the aisle is not currently costing anything: tightening it by six inches gains no desks at all, because the sixth band stays far out of reach. Widen it by six inches and the four aisles between the five bands ask for 24 more inches when only 14 are spare — a whole band goes, and four desks with it.
That asymmetry is worth knowing before the aisle width becomes a negotiation. Tightening it here buys nothing and widening it costs four desks, and the two situations look identical on a plan. On a different plate the signs reverse, which is the argument for checking rather than assuming.
Where this stops
Identical rectangles in a clean rectangle is the easy version of the problem. Real plates have a core in the middle, columns on a grid that never matches the desk pitch, glazing mullions the desk lines want to align to, doors that swing into the aisle you just measured, and a ceiling that decides where power and screens can land. Every one of those costs desks, and the count here is the ceiling rather than the answer.
It also says nothing about what is permitted. Aisle widths, routes, egress and occupant load are set by the code the building department enforces and by your lease, and every dimension on this page is one you entered. For the money side, the load factor calculator turns the desk count into a cost per seat a month, and the hot desk ratio calculator says how many members a given number of desks actually supports. For a single desk against a single room rather than a floor of them, the desk depth and room fit calculator is the right tool, and turning space covers the circle a room still has once things are standing in it. If your problem is machines rather than desks, the workshop layout planner handles infeed and outfeed runs, which desks do not have.
Questions people ask
How many square feet does one desk need?
The defaults land at 91 gross square feet a desk, and that number is an output rather than a rule — it falls straight out of the desk size, the chair zone, the aisle width and how much of the floor goes to meeting rooms and perimeter walkway. Change any of those and it moves. Quoting a square feet per desk figure without saying what aisle and what shared rooms it assumes is how two plans that look identical end up ten desks apart, which is why this page asks for the pieces instead.
Do back to back desks really gain that much?
At the defaults they take the same floor from 32 desks to 36, which is one desk in eight. The reason is that a standalone row spends a whole chair zone and a whole aisle on one row of desks, while a back to back band spends two chair zones and one aisle on two rows. The aisle is the saving. It is not universal, though: sweep the inputs and benching wins on roughly two thirds of plates, ties on a fifth, and actually loses on narrow ones, where a ten foot back to back band will not fit across the depth but two shallow standalone bands will. The calculator reports both every time rather than assuming, and on a narrow floor it is worth reading that line before ordering furniture. Whether people will work at a bench is a separate question again, and one this page cannot answer.
Why does the count change when I rotate the layout?
Because the band pitch has to divide into the depth available, and the remainder is wasted. At the defaults the pitch is 13 feet 10 inches: one way round the depth is 35 feet and takes two bands, the other way it is 71 feet and takes five. Desks per row move the opposite way, nine against four, but not by enough to cancel it — forty desks against thirty-six. It is the cheapest thing to test and the easiest to forget, because a plan tends to inherit its orientation from whoever drew the first sketch.
What should I put in the perimeter strip field?
Whatever walkway you intend to leave against the walls, measured as your own design decision. This page supplies no required width and states no rule, because circulation and egress widths are set by the code your building department enforces and by the terms of your lease, and they differ by jurisdiction and by building. If you have been given a dimension by an architect or the building department, use that one. If you are sketching, use what you would be comfortable walking past a seated person in.
How accurate is the column allowance?
It is deliberately crude: one desk lost per column. In practice a column in the middle of an aisle costs nothing, one in the corner of a bay costs nothing, and one landing exactly where a desk wants to be costs one and sometimes disrupts the whole row. Use it as the pessimistic end of the range and refine it once you have the column grid on the plan, because column positions are the single most common reason a real layout comes in under the packed count.