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House Construction Budget Calculator
Estimate a house building budget from floor area and construction price per square metre, including design, permits, fencing and external works and a contingency, to plan funds and compare contractor quotes.
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Estimate a house building budget from floor area and construction price per square metre, including design, permits, fencing and external works and a contingency, to plan funds and compare contractor quotes.
How it works
House construction = total floor area × price per sq m. Design = construction × design %. Subtotal = construction + design + permits + external works. Contingency = subtotal × contingency %. Total = subtotal + contingency.
Hand check: a 100 sq m house at THB 10,000 per sq m costs THB 1,000,000 to build. 5% design adds THB 50,000; with no other costs a 10% contingency is THB 105,000, for THB 1,155,000 in total or THB 11,550 per sq m.
The price per sq m in the field is an example; real prices depend on design, structure, soil, foundations, materials, location and timing. Land, land filling, loose furniture, loan interest and taxes not in a contractor's price are excluded. Use drawings and a bill of quantities from professionals before signing.
Frequently asked questions
What counts as floor area?
All roofed floor space on every level. Some contractors price balconies, carports or eaves at different rates, so ask how area is measured in the quote.
How much contingency is sensible?
Allow more when drawings are incomplete or changes are likely. With full construction drawings and a BOQ, uncertainty falls.
Can I use this for a construction loan?
As a first budget, yes, but banks assess the drawings, permits and their own valuation, and release money by construction stage.
Sources
Method last verified 21 Sep 2026