Modular Grid Calculator
How a plan dimension breaks into a planning module — how many modules fit, what is left over, and the dimension that would fit exactly — for setting out on a grid.
Modular coordination sets every dimension as a multiple of a module — 300 mm, 600 mm, 1,200 mm — so components fit without cutting.
How the modular grid calculator works
Modular coordination sets every dimension as a multiple of a module — 300 mm, 600 mm, 1,200 mm — so components fit without cutting. A 7.5-meter bay on a 600 module is 12.5 modules: it fits twelve and leaves 300 mm, which is a half-module and a problem.
The useful output is the nearest dimensions that fit exactly, above and below, so the plan can be nudged onto the grid.
Formula: modules = floor(L / M); remainder = L − modules × M
Worked examples
| Inputs | Whole modules that fit | Note |
|---|---|---|
| 7,500 on a 600 module | 12 | half a module over |
| On the grid | 12 | fits exactly |
| A 1,200 module | 6 | fewer, larger modules |
FAQFrequently asked questions
What is a planning module?
A base dimension every part of a building is set out on — 100 mm internationally, with 300, 600 and 1,200 as the working multiples. It lets components fit without cutting.
Why 600 mm?
Because it is the module most building products are made to: plasterboard, ceiling tiles, stud spacing, cabinets. A plan on 600 wastes less of all of them.
What if a dimension does not fit?
Nudge it to the nearest multiple, or use a secondary module for the odd part. A half-module remainder is common and manageable; a random one is not.
Does this apply to structure?
Structural grids are usually larger multiples — 7.2, 8.4, 9.0 m — chosen so the planning module divides them. Check both.
What about walls and tolerances?
Modular coordination sets out to a reference grid; the actual components are slightly smaller to leave joints. This page handles the grid, not the joints.
Where these figures come from
- Sabine (1922) — Collected Papers on Acoustics — the reverberation-time equation
- CIBSE Guide A — Environmental design — daylight, comfort and ventilation criteria
- Neufert — Architects' Data — the standard reference for space and dimension
- International Code Council — International Building Code — occupant load and egress factors
- International Code Council — publisher of the model codes most US jurisdictions adopt
Last checked: September 2026. Formulas are the standard building-science and code relationships; default thresholds are common international values and should be replaced with the ones in your code.