A build budget with hard costs, soft costs and contingency kept separate — because soft costs add 15–25% that most estimators leave out entirely, and lumping contingency into the headline hides how much of your budget is a guess. Also shows cash flow by phase, since running out of money in month four is a different failure from being over budget overall.
Construction Cost Estimator
LiveOverride this with a local figure if you have one. The default is the 2026 NAHB national average for standard residential construction. A quote from a local builder, or a recent comparable build, beats any national number.
Why cost-per-square-foot is nearly useless on its own
It is the number everyone asks for and the one that misleads most. The range within any single building type is enormous — "residential construction costs $150 to $450 per square foot" is technically accurate and practically worthless.
| Driver | How much it moves the number |
|---|---|
| Region | The single largest factor. Rural Midwest runs around 0.80× the national average; New York and San Francisco reach 1.42×. That is a 78% spread before anything about the building is decided |
| Quality level | Economy to luxury spans roughly 0.75× to 1.80× — the same house, built twice, differing by a factor of 2.4 |
| Complexity | A rectangular single-storey on a level site against an irregular plan on a slope: 0.92× to 1.25× |
| Size efficiency | Larger homes cost slightly less per square foot — kitchens and bathrooms are the expensive rooms and their count does not scale with area |
| What is included | Some quoted figures are hard cost only. Others include soft costs, or land, or neither. Two "cost per square foot" numbers frequently measure different things |
The practical consequence: a national average tells you almost nothing about your project. A recent quote from a local builder, or the actual cost of a comparable build nearby, is worth more than any published benchmark — which is why the base rate above is editable rather than fixed.
Soft costs: the 15–25% that gets forgotten
Most estimators return hard costs — materials, labour and contractor margin — and stop. Soft costs are everything else required to get the building finished and legal, and they are routinely omitted from the number people budget against.
| Soft cost | Typical share | What it covers |
|---|---|---|
| Design & engineering | 5–12% of hard | Architect, structural engineer, MEP, surveys. Higher for custom work, lower for a stock plan |
| Permits & fees | 2–5% | Plan review, inspections, impact fees, utility connections. Varies enormously by jurisdiction |
| Site works & utilities | 3–10% | Clearing, excavation, driveway, service connections. Can exceed 15% on a difficult site |
| Financing & insurance | 3–6% | Construction loan interest, builder's risk cover, title and closing costs |
On a $405,000 hard cost, 20% in soft costs is $81,000 — a sum large enough that discovering it late reshapes the whole project. Budget for it from the start rather than absorbing it into contingency, where it hides the fact that your real contingency is now zero.
What contingency is actually for
| Contingency | Appropriate when |
|---|---|
| 10% | Drawings complete, fixed-price contract, experienced builder, known site |
| 15% | The standard allowance for a conventional new build |
| 20% | Early design stage, owner-builder, or anything unusual in the design |
| 25%+ | Renovation of an existing structure, unknown ground conditions, heritage constraints, volatile material markets |
Renovation deserves the highest figure for a specific reason: you cannot see inside walls until you open them. Rot, non-compliant wiring, asbestos and undersized structure are found rather than predicted, and each one changes the scope after work has started.
What the overrun research actually shows
Cost overruns are not an unlucky outcome — they are the normal one, and the figures are consistent across decades of research:
| Finding | Figure | Source |
|---|---|---|
| Projects exceeding budget | Almost 9 in 10 | Flyvbjerg, Holm & Buhl (2002), 258 infrastructure projects |
| Average overrun | 28% | Same study. Autodesk reports 27% across all project types |
| Landing within 10% of budget | 25–31% | KPMG global construction survey |
| Overruns traceable to estimating errors | 32% | Industry estimating research, 2026 |
| Cost overruns caused by design changes | 56.5% | Change order research — design errors and omissions are the dominant category |
| Change orders as a share of contract value | 10–15% | Major projects. Some reach 25% or more |
Escalation: prices move while you build
A twelve-month build does not pay today's prices. Materials and labour drift throughout, and on a long project that drift is a line item rather than noise.
| Region | Forecast | What is driving it |
|---|---|---|
| Africa | 7.0% | Highest globally — currency depreciation, hyperinflation in several markets, political instability |
| Middle East | 5.1% | Second highest. Data-centre and AI infrastructure demand is pulling skilled labour away from traditional sectors, deepening shortages |
| Australia & New Zealand | 4.9% | The most acute labour shortages of any region |
| Global average | 4.5% | Up from 4.2% in 2025, expected to flatten in 2027 |
| North America | 3.8% | Highest labour costs worldwide at US$79.50 an hour average. US input prices rose 41.6% between Feb 2020 and Mar 2025 |
| United Kingdom | 3.5% | Strong demand from investment seeking regional stability |
| European Union | 2.8% | Lowest globally — several major economies still recovering from earlier inflationary pressure |
Escalation applies at the midpoint of the build, not the end. Spending is spread across the period, so a 24-month project at 6% carries roughly 6% escalation on the whole budget — not 12%. The calculator applies this convention automatically.
The old 3–5% contingency buffer is no longer adequate for anything long. Projects running beyond six months now typically require 10–15% contingency plus an explicit escalation clause tied to a commodity index.
What building costs worldwide
Construction cost varies more between cities than between building types. The most expensive markets, from the same 112-market survey:
| City | Per m² | Per sq ft | Note |
|---|---|---|---|
| New York | $7,938 | $737 | The most expensive construction market in the world |
| San Francisco | $7,883 | $732 | Second, and closing |
| Geneva | $6,985 | $649 | Highest outside the US |
| Zurich | ~$6,900 | ~$641 | Swiss labour and regulatory costs |
| London | $6,032 | $560 | Fifth globally |
Commercial benchmark rates, not residential — but the ratios between cities hold reasonably across building types. A residential build in New York costs several times what the same build costs in a low-cost market, which is why any national average needs a regional multiplier before it means anything.
Average hourly construction wages reached US$79.50 in North America, $75.60 in Europe and $68.00 in Australia and New Zealand. 71 of 99 surveyed markets report a skills shortage — and that shortage, rather than material prices, is what is keeping inflation above target. Material prices have largely steadied; wages have not.
Contract type decides who carries the risk
| Contract | Overrun risk sits with | Requires |
|---|---|---|
| Guaranteed Maximum Price | Contractor, above the cap | A fully defined scope. Unsuitable where design is incomplete at tender — the contractor will price the uncertainty in, or refuse |
| Lump sum / fixed price | Contractor | Complete drawings. Changes become change orders, priced without competition |
| Cost plus fee | Owner, entirely | Trust and active oversight. Appropriate when scope genuinely cannot be defined, expensive otherwise |
| Time and materials | Owner, entirely | Tight scope control. Best kept to small or investigative work |
The pattern is consistent: the more protection a contract gives the owner, the more complete the design must be before signing. A GMP on incomplete drawings is not protection — it is a contractor pricing in every unknown they can imagine, and you paying for all of them whether or not they occur.
Sources: Flyvbjerg, Holm & Buhl, Journal of the American Planning Association (2002) · KPMG Global Construction Survey · Turner & Townsend Global Construction Market Intelligence 2026 (112 markets, 44 countries, surveyed March 2026) · AACE International Recommended Practice 17R-97 (estimate classification) · Associated Builders and Contractors input price data. Cited for the specific figures above.
Cash flow matters as much as the total
Running out of money in month four is a different and worse failure than being over budget overall — a stalled site accrues cost while producing nothing, and restarting a trade that has moved on can take weeks. Construction spending follows a predictable S-curve:
| Phase | Share of budget | Note |
|---|---|---|
| Design, permits, mobilisation | 8% | Spent before anything visible happens — a common source of early alarm |
| Foundation and structure | 22% | Heavy spend, fast progress |
| Envelope — roof, windows, cladding | 20% | Weathertight is the milestone that de-risks everything after it |
| Systems — MEP, insulation, plaster | 25% | The largest single phase, and the least visible |
| Finishes | 20% | Where scope creep concentrates, because it is the part you can see |
| Completion and snagging | 5% | Always takes longer than the money suggests |
Common mistakes
Frequently asked questions
How accurate is this estimate?
Roughly ±20–30%, which is the AACE Class 5 classification for a conceptual estimate made from square footage before drawings exist. That sounds imprecise because it is — and any tool claiming better accuracy from the same inputs is overstating what it can know. Use it for feasibility. For a loan application or a contract you need a Class 3 estimate from a professional estimator working off drawings.
What is the average cost per square foot to build a house?
The 2026 US national average sits around $162 per square foot for standard residential hard cost, with a working band of roughly $145–195. But regional variation swamps the average: the rural Midwest runs near $100–150 while the West Coast reaches $220–280. A local builder's quote is worth more than any national figure, which is why the base rate in this calculator is editable.
What are soft costs and why do they matter?
Everything that is not materials and labour: design, engineering, permits, utility connections, financing interest, insurance. They typically add 15–25% on top of hard costs and are the most commonly omitted part of a budget. On a $400,000 build that is $60,000 to $100,000 — enough that finding out late changes what is possible.
How much contingency should I allow?
Fifteen percent for a conventional new build with complete drawings. Twenty for early design or an owner-builder, and twenty-five or more for renovation, where you cannot see inside walls until you open them. The critical discipline is that contingency covers unknowns, not upgrades — the moment it funds a nicer worktop, you no longer have one.
Why do two calculators give me such different numbers?
Usually because they include different things, or because one has stale rates baked in. Construction pricing moved sharply after 2020, and a tool that hardcodes dollar figures becomes wrong without any visible sign. Check what each includes — hard cost only, or with soft costs, or with land — and check when its rates were last updated. Where a tool does not say, treat the output cautiously.
Does building bigger cost less per square foot?
Slightly, yes. Kitchens and bathrooms carry the highest cost per square foot in a house, and their number does not scale with floor area — a 3,000 sq ft home rarely has twice the bathrooms of a 1,500 sq ft one. The extra area is mostly bedrooms and living space, which are comparatively cheap. Total cost still rises substantially; only the rate softens.
Should I include land in the budget?
Not in this one — it estimates construction only. Land and its acquisition costs are usually a separate line and vary far more than the building. National figures showing total project cost around $665,000 against $323,000 for construction alone illustrate the scale: land and associated costs frequently exceed the building itself.
Is my input stored?
No. Everything runs in your browser with no server request, and works offline once the page has loaded.
Related calculators
See the full list of Construction calculators, or try:
- Concrete Calculator — volume, bags and mix for the foundation
- Square Footage Calculator — area before anything else
- Construction Loan Calculator — interest during the build
- Mortgage Calculator — the permanent financing after completion
- Roofing Calculator — squares from footprint and pitch
- Beam Deflection Calculator — structural sizing checks