# How to estimate the cost of building a house by the square foot

Richard Arthur Norton (CC-By 2.5)

There are many ways to estimate the cost of building a home design. Though not necessarily the most accurate method, using the total square footage of the house and a rule of thumb dollar per square foot for the area and type of house is an easy way to get a rough idea of the potential cost. Calculate square footage.

There are many ways to estimate the cost of building a home design. Though not necessarily the most accurate method, using the total square footage of the house and a rule of thumb dollar per square foot for the area and type of house is an easy way to get a rough idea of the potential cost.

Calculate square footage. Although it seems this would be very straightforward, a major factor that can skew a building cost estimate is the difference between finished square feet and constructed square feet, which includes areas such as basements or garages that don't receive the same degree of work and therefore cost less. Unfinished rooms, such as basements and garages aren't free to build, though, so excluding them from an estimate will produce an artificially low figure.

Identify price per square foot by region and style. Most cost per square foot estimates are given by region and assume an average house. If your house is not average, say, for example, it's going to include luxurious interior or exterior finishes and high-quality materials, using the average cost per square foot in the region is going to produce inaccuracies. Consult the builder for the best square footage estimates based on your particular home plan.

Multiply, and, if necessary, add. In the most simple, but least accurate, estimates, multiply the square footage by the cost per square foot. A more precise estimate can be obtained by using different cost per square foot estimates for finished and unfinished space and adding the total costs for these areas together.

Anticipate overruns. A cost estimate is just that, an estimate. Don't surprised if unforeseen expenses unique to a project (such as, say, levelling the terrain) cause the actual total cost to be somewhat higher, even as much as 10 to 15 per cent. This, however, also doesn't mean the cost can't come in lower. Understand your estimate to represent an area into which the total cost is likely to fall. Don't agree to a plan that's too expensive, or routine overruns can jeopardise the financing.