Core Formulas
| Item | Formula |
|---|---|
| Rectangular floor | length × width |
| Ceiling | length × width |
| Wall | length × height |
| Four walls | sum each wall area |
| Opening | width × height |
| Room perimeter | sum all wall lengths |
Irregular Rooms
Split an irregular room into rectangles or other simple shapes, calculate each area separately, then add the results. Keep a sketch with every measurement marked.
Example
Floor: 4.8 m × 3.6 m = 17.28 m².
Two identical long walls: 2 × (4.8 × 2.4) = 23.04 m².
Two identical long walls: 2 × (4.8 × 2.4) = 23.04 m².
Measuring Tips
- Use consistent units.
- Measure at more than one point if walls are not square.
- For ordering materials, follow the supplier’s coverage and waste guidance.