The most straightforward way to measure internal floor area is by measuring the external dimensions of your house, but you can also measure from the inside with an adjustment for wall thickness. You can perform these measurements using either feet or metres.
Method 1: Measuring from Outside (The Best Way)
According to the reference, the best way to measure the floor area is from the exterior.
- Go outside the property.
- Measure the total length of the house from one end to the other (including walls).
- Measure the total width of the house from one side to the other (including walls).
- Multiply the measured length figure by the measured width figure.
This calculation gives you the approximate total floor area, including the space taken up by the external walls, which is often how total area is calculated.
Method 2: Measuring from Inside
If measuring from the outside is not possible, you can measure from the interior.
- Measure the internal length of the space you wish to calculate the area for.
- Measure the internal width of the space.
- Add the thickness of the walls to these internal measurements. This step is crucial to account for the space occupied by the walls themselves, effectively converting your internal measurements closer to external dimensions before calculating the area.
- Multiply the adjusted length figure (including wall thickness) by the adjusted width figure (including wall thickness).
This method requires knowing or estimating the wall thickness to get a figure comparable to the external measurement method.
Comparing Measurement Methods
Here's a quick look at the two approaches:
| Feature | Measuring from Outside | Measuring from Inside |
|---|---|---|
| Recommended? | Yes, cited as "the best way". | Use if outside measurement isn't possible. |
| Steps | Measure length & width outside; multiply. | Measure length & width inside; add wall thickness; multiply. |
| Complexity | Simpler, fewer variables. | Requires accounting for wall thickness. |
| Units | Feet or metres. | Feet or metres. |
Whether you measure in feet or metres, consistency is key. Use the same unit for both length and width measurements before performing the multiplication.
