How this calculator works
The number of desks in a row is the largest whole number whose desks and gaps fit across the room. A row of n desks needs n desk lengths and n - 1 gaps, so n = floor((room length + gap) / (desk length + gap)). The same rule gives the number of rows down the room. Multiplying rows by columns gives the rectangular capacity. The actual gap is then what is left after the desks are placed, spread evenly between them, which is usually a little larger than the minimum. A staggered layout offsets alternate rows by half a desk: it improves sightlines and group work, but because every second row holds one fewer desk, it rarely beats the rectangular count at the same minimum gaps.
Formula
columns = floor((room length + side gap) / (desk length + side gap)). rows = floor((room width + front gap) / (desk width + front gap)). Rectangular capacity = rows x columns. Staggered capacity = ceil(rows / 2) x columns + floor(rows / 2) x (columns - 1). Actual side gap = (room length - columns x desk length) / (columns - 1), and similarly for the front gap; with one row or column the leftover is the whole difference.
Worked example
An 8 m by 6 m room, 0.6 m by 0.5 m desks and a 1 m gap both ways fits floor((8 + 1) / (0.6 + 1)) = 5 desks across and floor((6 + 1) / (0.5 + 1)) = 4 rows, for 20 desks. The side gap actually achieved is (8 - 5 x 0.6) / 4 = 1.25 m, and the front gap is (6 - 4 x 0.5) / 3 = 1.33 m. A staggered layout would seat 18, because the two offset rows lose one desk each.
Advertisement
Frequently asked questions
How do I convert six feet to metres?
Six feet is 6 x 0.3048 = 1.8288 m, which rounds to about 1.83 m. Enter 1.83 in the gap fields, or switch the unit selector to feet and enter 6. The calculator converts everything to metres before working.
Should the gap be measured between desk edges or between students?
The calculation uses the gap between desk edges, which is the usual planning rule. If the guidance is stated as distance between people, add the desk depth in the direction being measured, or measure from seat centre to seat centre and enter the centre distance as the gap plus half a desk on each side.
Does the capacity include the teacher desk, doors and storage?
No. It treats the room as an empty rectangle. Set aside space for the teacher area, door swings, cupboards and walkways first, and use the reduced usable length and width. Local fire codes may also cap the number of occupants, which can be lower than the geometry allows.
Why does the staggered layout fit fewer desks?
Each offset row has one desk fewer than a full row, so the staggered count is rows x columns minus one for every second row. Staggering helps when the requirement is a diagonal distance between students, but this calculator measures the side and front gaps along the room axes, where the rectangular grid is the most efficient.