AI-generated cabin concept, used for illustration.
In this guide
An A-frame cost per square foot is a ratio, not a complete estimate. Before using it, ask what spending is in the numerator and what floor area is in the denominator. Sloped walls and lofts make that second question especially important.
Ask which area was counted
A supplier may describe the exterior footprint, internal floor area, combined ground and loft area, or area above a stated headroom. Those measurements answer different questions. Request a dimensioned drawing and the measurement rule used in the quote.
Record covered decks separately. A deck can add useful living space and construction cost, but it does not provide the same enclosed accommodation as a bedroom. Similarly, low storage under a slope can be useful without being comfortable standing space.
Work through a comparison
Here is an arithmetic example, not a market price. If the same $120,000 scope is divided by 600 square feet, the result is $200 per square foot. Dividing it by 800 square feet produces $150. The project did not become cheaper; the area definition changed.
For international comparisons, 600 square feet is approximately 55.7 square metres. Convert the area and currency consistently, and retain the quote date. Converting units cannot correct a different scope of work.
Keep the ratio beside the complete proposal
Request three things from each bidder: the included work, the defined floor area and the total amount. Then compare the actual rooms, storage and services. A compact design with a higher ratio may still have a lower total cost and suit your needs better.
Use the ratio to investigate differences after the scopes match. Do not use it to supply missing site-work or foundation prices. General project-budget context is available in Your Home: affordability; local estimates must come from people pricing the actual site.