Property Development Feasibility Calculator
This calculator tests whether a New Zealand property development stacks up financially before you commit capital. You enter the land purchase price, gross floor area, build cost per square metre and number of units, plus professional fees, council and consent fees (including development contributions), sales and marketing costs, and construction finance details: loan-to-cost ratio, interest rate and build period. You also enter the expected sale price per unit. The calculator returns a full development cost statement showing every cost line as a dollar figure and share of total development cost, then compares this against your gross development value to produce gross margin, return on cost and return on equity, alongside total development cost, equity required and cost per unit. A verdict banner flags the project as viable, marginal or unviable, and a sensitivity table shows how the gross margin holds up if build costs rise or sale prices fall by up to 10 percent. All figures are modelled ex-GST, matching how a GST-registered developer reports to IRD. Use it before you sign a land contract or lock in a build price, to stress-test your assumptions and see how much buffer you have if costs run over or the market softens. These are planning estimates only; get quantity surveyor pricing and your bank's lending terms before committing to any development.
Check your development numbers before committing
Enter your land, build, fees, and expected sale price to get a complete feasibility assessment
Reading Development Feasibility Numbers
A residential development is generally considered viable when the gross margin (profit as a percentage of GDV) exceeds 15% to 20%. Below 15%, the risk-adjusted return is thin for the time, capital, and complexity involved. Below 10%, most banks will not provide construction finance. Above 20%, the project is likely to proceed confidently.
Return on equity (ROE) measures how hard your contributed capital is working. At 65% loan-to-cost with an 18-month build, a 15% gross margin can produce an ROE of 30% or more on an annualised basis, which compares favourably to most passive investments. This leverage effect is why property development attracts capital even when gross margins look modest.
Development Contributions: NZ's Hidden Cost
Development contributions (DCs) are levied by councils on new residential developments to fund infrastructure: roading, water, wastewater, and reserves. DC rates vary enormously by council and have risen sharply in recent years. In Auckland, DCs for a new dwelling can exceed $50,000 to $70,000 per unit depending on location and infrastructure requirements. In Christchurch, DCs are lower but still material. Christchurch City Council publishes a DC calculator on their website; Auckland Council publishes their DC schedule annually. Always verify current DC rates for your specific location before completing a feasibility assessment.
GST on New Residential Builds
New residential builds sold by a GST-registered developer attract GST of 15% on the sale. This means if you quote buyers a price of $862,500 (inclusive), you retain $750,000 (ex-GST) and remit $112,500 to IRD. This calculator works entirely on ex-GST figures, consistent with how a GST-registered developer reports to IRD. If your build contract, professional fee invoices, and sale prices all exclude GST, the figures flow cleanly. If you are unsure about the GST treatment of any cost, consult your accountant.
Frequently Asked Questions
What return should I target on a NZ development?
Industry convention is 15% to 20% gross margin as a minimum for residential development. Banks typically require at least a 15% margin to support construction lending. More complex projects (apartments, multi-stage developments) or those in less certain markets may require 20% or more to justify the additional risk.
How is finance cost calculated here?
Finance cost is estimated as 50% of the peak loan amount (loan-to-cost ratio times TDC), multiplied by the annual interest rate, multiplied by the build period in years. The 50% factor approximates a progressively drawn-down construction loan rather than a fully drawn loan from day one, which would overstate the cost.
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