Home Renovation Budget Calculator

This calculator helps you plan a realistic budget for a home renovation in New Zealand, covering every major cost area plus a contingency for the surprises renovations almost always bring. Enter your total budget, then break your costs down across design and consents, building work, plumbing and electrical, fittings and finishes, and any other spending, before choosing a contingency percentage to add on top. The calculator adds these costs together, applies your contingency to that subtotal, and returns the total project cost including contingency, alongside your costs before contingency, the dollar value of the contingency itself, and how that total compares against your budget, showing whether you are over or under. This lets you see straight away whether your plan is realistic before a tradesperson is booked, and gives you room to trim scope or lift your budget if the numbers do not stack up. A contingency of around 10% to 20% is sensible for most projects, with older homes warranting a larger buffer because hidden problems such as rot, old wiring or non-compliant work are common once walls come off. Update your figures as quotes come in, and keep tracking the running total against your budget through the project rather than only at the start, so a blowout is caught early. This is a planning estimate only, and actual costs will depend on your contractor's quotes.

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A contingency of 10% to 20% is sensible, more for older homes where hidden problems are common. Build it in from the start so a surprise does not derail the project. Estimate only, to support planning.