223
Total cost: build vs buy
Land, construction, loan, and rent — priced against the existing home.
X VS Y COMPARISON · MONEY · HOUSING
Build vs Buy a Home
A $150,000 lot plus a 2,200 sq ft home at $200/sq ft versus buying an existing home for $585,000. The $/sq-ft quote is never the whole story: building also means construction-loan interest on every draw, twelve months of rent while the walls go up, and a build total of $631,600 against $611,700 all-in to buy. Enter your numbers and this calculator totals both doors — and prices the $241.8 monthly payment gap.
What the comparison shows
$150,000 for land plus 2,200 sq ft at $200/sq ft ($440,000 of construction), an 8% construction loan over 12 months, and $2,000/mo rent while you build — against a $585,000 existing home needing $15,000 of day-one repairs. The build door totals $631,600; the buy door totals $611,700.
| Output | Formula | What it means |
|---|---|---|
| Total build cost | land + (sq ft × $/sq ft) + construction interest + rent × months | The check you actually write to end up housed: $631,600 here, not the $440,000 the $/sq-ft quote suggests. |
| Construction interest | $/sq-ft cost × APR × (months / 12) × 0.5 | Interest accrues only on drawn funds, so the calculator assumes about half the cost is outstanding on average: $17,600 in this example. |
| Total buy cost | price × 1.02 + immediate repairs | Purchase price plus roughly 2% in closing costs and the day-one repairs: $611,700 here. |
| The gap | build total − buy total | Positive means building costs more. Here it is +$19,900: buying the existing home wins. |
| Monthly, both doors | 30-yr amortization at 6.75% on 80% financed | $3,277 to own the build vs $3,035 to own the resale — a $241.8/mo carrying-cost difference. |
Notice where the $/sq-ft quote misleads: it covers $440,000 of a $631,600 reality. The other $631,600 is land, the $17,600 of construction-loan interest, and the $24,000 of rent you pay while the home is being built — three costs the existing-home buyer never faces.
Who uses this
- The landowner who already owns the lot: drop land from the build side and the verdict often flips — set land cost to what you paid, or to $0 if it is free and clear.
- The custom-dream buyer who wants a floor plan no production builder offers: the calculator tells them exactly what the dream costs over the resale, so the premium is chosen, not stumbled into.
- The bidding-war refugee in a hot market where existing homes sell $50,000 over asking: building dodges the auction, but the rent-during-build and loan interest eat part of the savings.
- The edge-of-town family comparing a $585,000 resale near work against building on a cheaper lot further out: the calculator prices the commute-home trade they are really making.
Accuracy & limitations
The $/sq-ft construction figure excludes land — that is why land is its own field (NAHB’s $162/sq-ft 2024 average is construction only, on 4,000 builders’ homes averaging 2,647 sq ft). Construction interest assumes roughly linear draws (the 0.5 factor); lumpy draw schedules move it either way. The 12-month default matches contractor-built custom homes (11.7 months, Census Survey of Construction 2025) — owner-built runs about 14.3 months, so add rent and interest if you are your own general contractor. Cost overruns are not modeled: pad the build budget 10–15%% before trusting a close verdict, and remember the appraisal-gap risk — lenders appraise the plans, and if the finished home appraises below cost you cover the difference in cash. Monthly payments assume both doors financed at 80%% loan-to-value, 30 years at 6.75%%, and ignore property-tax and insurance differences. Treat the verdict as the shape of the answer, then sanity-check the $/sq-ft figure against two local builder quotes.
Cite this calculatorBright Side Kit. “Build vs Buy a Home.” brightoolbox.com, 2026.
Bright Side Kit. "Build vs Buy a Home." https://brightoolbox.com/build-vs-buy-home/ Accessed October 22, 2026.Frequently asked questions
Is building a home cheaper than buying an existing one?
Right now, usually not on price alone. In Q4 2025 the median new single-family home sold for $405,300 while the median existing home sold for $414,900 (Census/NAR via NAHB) — the historic new-home premium has nearly vanished, and once you add land, construction-loan interest, and rent during the build, building typically lands above the resale. Our default example builds at $631,600 all-in versus $611,700 to buy. Build when you want exactly your home, or when local resales are bid up beyond reason — not to save money.
How long does it take to build a house?
The Census Survey of Construction puts the 2025 average at 8.8 months from permit to completion (NAHB analysis). Built-for-sale homes are fastest at 7.4 months; contractor-built custom homes on owner land average 11.7 months, and owner-built homes take about 14.3 months. Every extra month is another month of rent plus construction interest — the calculator’s 12-month default fits the contractor-built custom case.
What do construction loans cost in 2026?
Conventional construction-phase rates ran roughly 7–9%% in 2026 (one-time-close programs from ~6.5%%, two-close up to ~9%%). You pay interest only on drawn funds, not the full loan amount — which is why the calculator assumes about half the construction cost is outstanding on average. The loan then converts to a permanent mortgage. Expect 20–25%% down on total project cost and tighter underwriting than a standard purchase loan.
What is the appraisal-gap risk when building?
The lender appraises your plans, not a finished house. If the appraised value comes in below your build cost, the loan shrinks and you cover the difference in cash at closing — on top of your down payment. This bites hardest with unusual designs, over-improved finishes for the neighborhood, or soft local markets. Get a realistic appraised-value estimate before you commit to the build.
What about renovating the existing home instead?
Count it: the calculator’s repair field is for day-one fixes, but renovation creep is the resale door’s version of the build overrun. A $585,000 home plus a $120,000 kitchen-and-bath remodel can sail past the build total — add your honest renovation budget to the repair field before comparing. If the existing home needs more than ~20%% of its price in work, rerun the build side seriously.
When does building actually win?
Three cases: you already own the land (drop the land cost and the verdict often flips); comparable existing homes are scarce or selling far over asking; or you want a genuinely custom home and are willing to pay a known premium for it. A fourth: you act as your own general contractor with real experience — but then use the ~14-month timeline and honest subcontractor bids, not optimism.