Apartment floor area: compare usable space before price per square metre
Compare apartment floor plans on a consistent basis: internal area, balconies, walls, furniture clearance and the evidence behind a quoted price per square metre.
Two identical area figures can describe different homes
A listing that says 50 square metres leaves several questions unanswered. Does the figure include a balcony, internal walls, columns or a share of common space? Was it taken from a registered document, a sales plan or a site measurement? RICS guidance stresses documenting the measurement basis. Its current code page distinguishes the applicable guidance from archived standards, so a familiar acronym alone should not settle the question.
For a buyer considering Thailand, Bali or another market, this is a comparison problem before it is a design problem. Do not assume that the same English marketing term has the same legal or measurement meaning in every jurisdiction.
Ask for an area schedule, not a verbal assurance
Request the dated plan, its revision, the stated total and the components used to produce it. Ask which document controls the purchased area and what the contract says about any difference at completion. A referring agent can organise these questions, but a qualified adviser must interpret the legal effect of the documents.
Keep the source of every number visible. If a local representative measures a room with a laser, record it as an observation, not as a replacement for a survey. If the seller cannot provide a component breakdown, leave the comparison incomplete instead of inventing a conversion from total to usable area.
A worked example of a misleading comparison
The following amounts and areas are invented solely to demonstrate the calculation. They are not Phuket prices or a valuation.
| Item | Apartment A | Apartment B |
|---|---|---|
| Asking price | 5,000,000 THB | 5,000,000 THB |
| Advertised area | 50 m² | 50 m² |
| Internal area on the supplied comparison plan | 42 m² | 47 m² |
| Separate balcony component | 8 m² | 3 m² |
| Price per advertised square metre | 100,000 THB | 100,000 THB |
| Price divided by internal comparison area | approximately 119,048 THB | approximately 106,383 THB |
The second calculation does not prove B is the better purchase. A larger balcony may be a buyer's priority. It simply shows that the first price-per-square-metre figure hides a meaningful difference in the distribution of space.
Test the floor plan with the buyer's actual furniture
Use dimensions rather than decorative furniture symbols. Check the bed, opening wardrobe doors, dining chairs pulled out and the path through the room. Measure clearances around columns and inward-opening doors. A desk drawn under a window may occupy the same space as curtains or an air-conditioning outlet.
For a home office, record the required desktop and chair movement. For a family, consider where luggage, a pushchair or cleaning equipment will go. These are practical requirements, not universal minimum dimensions; the buyer's needs and local accessibility requirements must be considered separately.
Keep legal area and comparison area distinct
Label each column clearly in the shortlist: advertised area, documented area and any separately measured internal space. Do not rewrite the seller's figure under a new name. If the unit is under construction, obtain the current plan and the contractual process for changes. A rendering should not be scaled to derive missing measurements.
The useful output is an annotated comparison sheet that another person can check. If the measurement basis is still unknown, mark that field unknown and request clarification before using the ratio in an investment presentation.
Questions buyers and agents ask
Is a balcony worthless in the calculation?
No. Its usefulness depends on the buyer, climate, privacy and layout. Separate it so the buyer can judge it consciously.
Does a lower price per square metre mean a bargain?
No. Condition, rights, location, charges and many other differences remain. The ratio is one comparison tool, not a valuation.
Should every developer use the same international standard?
Do not assume that. Ask which basis applies and which local documents control the transaction. International guidance does not override local law.
Sources and scope
RICS: Code of Measuring Practice. The numerical example and furniture checks are IBG Property editorial illustrations, not a certified survey.
Educational material. Examples are illustrative; legal, technical, tax and investment decisions need case-specific professional advice.
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