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Buy vs Build House Calculator

Work out whether it's cheaper to buy an existing home or build a new one on your own land.

How it is calculated

Two totals are added up and compared:

buy = home price + renovation budget
build = land cost + (cost per sqft × size in sqft) + permits and fees
difference = |build − buy|

All money is in dollars and the size is in square feet, not square metres, so a metric cost per m2 must be converted first (1 m2 is about 10.76 sqft). The land cost sits on the build side, so enter 0 only if you really already own the land. The tool shows which total is lower and by how much; equal totals give "Both options cost the same". Every field must be filled in (use 0 where something does not apply), none can be negative, and the size must be above zero; otherwise there is no result. It leaves out mortgage interest, closing costs, finishing upgrades, cost overruns and the extra months of rent while building.

Worked example

An existing home costs $420,000 and needs $35,000 of work, so the buy total is $455,000.00. Building means $90,000 for land, 2,200 sqft at $150 per sqft = $330,000, plus $12,000 in permits: 90,000 + 330,000 + 12,000 = $432,000.00. Build − buy = 432,000 − 455,000 = −23,000. The tool reports a cost difference of $23,000.00 with the verdict Building is cheaper. This ignores that a new build usually takes longer and tends to run over budget.

Try this example →

Common mistakes

  • Entering the size in square metres. The field is in square feet, so 200 m2 entered as 200 makes the build look about ten times cheaper than it is.
  • Leaving the size at 0 to see "just land and permits". A size of zero gives no result at all, because a house needs an area.
  • Leaving the land cost at 0 when you still have to buy the land. The build side then misses a large part of the real cost.
  • Using a per-sqft price that covers only the shell. Finishing, driveway, utility connections and landscaping may not be in it, and the tool adds nothing on top.
  • Treating the difference as the whole story. It is a cost comparison only; build time, rent while waiting, cost overruns and loan interest are not included.

About this calculator

A buy vs. build comparison adds up the total cost of two paths to homeownership: buying an existing home (purchase price plus renovation costs to bring it to the desired standard) versus building a new house (land cost plus construction cost per square foot plus permit and other fees; enter 0 for land if you already own it). Comparing the two totals shows which route is actually cheaper for a given target home size and quality.

Homebuyers and self-builders run this comparison because the two paths involve very different cost structures — an existing home has a known purchase price but often hidden renovation needs (roofing, electrical, plumbing), while new construction has a more predictable per-square-foot cost but adds land, permit fees, site work, and typically a longer timeline before move-in. Builders and real estate agents also use similar cost-per-square-foot benchmarks when advising clients on land they already own versus resale inventory in their market.

On one side, the price and renovation budget of an existing home; on the other, land, construction cost per square foot, size in square feet and permits for a new build: both totals appear side by side so you can see which is cheaper for you.

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