Classroom spacing calculator

Zero or negative spacing, length, or width is rejected with invalid_input instead of inventing infinitely many desks.

How student capacity is derived from room size and spacing

Leftover strips that are shorter than one full spacing become unused_length and unused_width rather than a partial student, which matches the geometry of a full cell that does not fit. On success the tool echoes rounded length, width, and spacing, then publishes layout_rows, seats_per_row, max_capacity, a compact layout string, leftover strips, formula, message, and ordered substitution steps you can audit by hand.

How to call the API and what comes back

String forms of numbers are accepted when they match a strict finite numeric pattern; unit suffixes, thousand separators, or free text fail validation. Prefer sending numbers rather than pre-formatted strings when you control the client; when you must send strings, avoid unit labels that would fail the finite-number pattern. Round-trip checks are easy: recompute floor of length over spacing, floor of width over spacing, multiply, and confirm the published capacity and leftover strips match. Send a JSON body with three required fields: length (aliases room_length, classroom_length, depth, L), width (aliases room_width, classroom_width, W), and spacing (aliases student_spacing, seat_spacing, distance, gap, S). All three must be finite positive numbers within the published absolute range so the products, ratios, and leftover strips remain finite in IEEE double precision on the Worker and in the browser. On success the response echoes rounded length, width, and spacing, sets area to length times width, cell_area to spacing squared, layout_rows to the non-negative integer floor of length over spacing, seats_per_row to the non-negative integer floor of width over spacing, max_capacity to their product, layout to a compact rows-by-seats string, unused_length and unused_width to the leftover strips, used_area and unused_area to the filled and leftover floor, formula to the published identities, message to a short English summary, and steps to an ordered substitution log. Failed validation—missing fields, non-finite numbers, zero or negative spacing, non-positive room dimensions, or values outside absolute limits—returns invalid_input and is never charged. Pricing is a flat $0.002 per successful request with unit item. Swap length and width if you want the opposite orientation; the product stays the same while layout_rows and seats_per_row trade places.

Practical tips, limits, and related searches

Measure the clear seating rectangle after subtracting the teaching wall strip, storage, and any aisle you will not occupy, then choose a spacing that matches your desk pitch, distancing policy, or exam layout—one and a half metres, two feet, or a custom pitch are all valid as long as the three numbers share a unit. Keep dimensions inside the published absolute range so counts cannot overflow into non-finite results the solver must reject. Prefer this capability when you already know usable length, usable width, and target square-grid spacing and only need an integer capacity plus a row layout; if your source is a single area and a square-metre-per-person rule, convert that rule into a linear spacing yourself or use an area-only plant-style count, which will not report layout rows. If unused_length or unused_width is large, either reduce spacing slightly so more whole cells fit, enlarge the room, rotate the grid by swapping length and width for a different row count, or accept the remainder as a circulation strip; this calculator never adds a partial student. When teaching or writing tests, pair an exact multiple (length ten, width eight, spacing two → five layout rows, four seats per row, twenty students) with a remainder case that leaves leftover strips, and include a deliberate zero or negative spacing to prove the invalid_input path. This landing targets people searching for a classroom spacing calculator, how many students fit in a room, seating capacity from room dimensions, layout rows for desks, or student spacing online; it is not a fire-code occupant-load estimator, not a furniture CAD placer, not an HVAC sizing tool, and not a credit-hour or course-load calculator. Failed tasks that return invalid_input do not consume prepaid balance, which keeps exploratory scripts cheap when you deliberately send zero spacing to verify error handling. School business officers, campus planners, and SaaS facilities tools can all call the same endpoint for reproducible take-offs without sharing a spreadsheet formula that drifts between browsers.