Free House Insurance Calculator for New Zealanders
Since 2013, NZ house policies are sum-insured. You pick the dollar amount the insurer will pay out at most. Get the number right by basing it on rebuild cost per square metre, not market value.
Your home
Based on 180 sqm at $3,200/sqm plus extras and demolition allowances.
About our House Sum Insured Calculator
NZ house insurance has been sum-insured since the post-Christchurch shift in 2013. The policy pays up to the figure you pick, no more. Underestimate it and a total loss leaves you paying the gap; overestimate it and you pay a slightly higher premium each year. The calculator gives a starting figure based on the same per-sqm rebuild method NZ insurers use behind the scenes.
The base of the calculation is floor area times rebuild cost per square metre. Mid-range NZ rebuilds in mid-2026 sit around $2,800-$3,500 per sqm in regional towns, $3,500-$4,500 per sqm in Auckland and Wellington, and higher again for premium finishes. Add 10-15% for demolition cost, plus an allowance for outbuildings, decks, and external works.
Move the build-quality slider to see how a basic-finish vs premium-finish assumption changes the figure. Move the floor-area slider to see how a 200 sqm vs 250 sqm change shifts the rebuild cost; in NZ, every 10 sqm typically adds $30,000-$45,000 of rebuild cost.
How to use it
Enter the floor area of the main dwelling in square metres. Use the figure on your council file or the rating valuation; if you have an architectural plan, take the figure from there. Pick a per-sqm rate that matches your build quality and region; the default is a mid-range NZ figure.
Add allowances for any extras (detached garage, decking, retaining walls, fencing, garden paths) and a demolition allowance of 10-15% of the build cost.
The result panel returns the suggested sum insured, the per-sqm equivalent, and a breakdown of build cost vs extras vs demolition. Round up to the nearest $10,000 when entering it on a policy.
Why use it
The Christchurch earthquake aftermath taught the insurance industry, and many NZ homeowners, that "rebuild cost" is the only figure that matters in a total loss. Many homes rebuilt at 30-50% above the previously assumed market-value-based sum, and the gap was paid by the homeowners. Setting the sum insured against rebuild cost (not market value) closes that gap before it appears.
The calculator also makes the 30-40% NZ construction-cost rise since 2020 visible. A sum insured set in 2020 at $580,000 for a 200 sqm Christchurch home would correspond to a 2026 rebuild cost of $760,000 or higher. Updating the sum insured at each renewal is the only way to keep up.
For new builds, the construction contract price plus any signed variations is usually a defensible sum insured for the first year. For homes 5+ years post-purchase, getting a registered valuer’s rebuild estimate every 3-5 years is worth the $700-$1,200 cost relative to the size of the cover decision.
The maths behind it
Sum insured = Floor area × Cost per sqm + Extras (deck, garage, fencing, paths) + Demolition allowance The base figure is your home’s floor area in square metres multiplied by a per-sqm rebuild cost. Cost per sqm reflects build quality (basic finish, mid-range, premium) and varies by region (Auckland and Wellington run higher than Invercargill and Whangarei). Extras cover anything beyond the main dwelling: detached garages, decks, retaining walls, paths, fences. Demolition allowance is typically 10-15% of the build cost to cover removing the damaged structure before rebuilding.
Worked example
Iris and Stephen, Blenheim, with a 200 sqm 1990s family home plus a detached garage and deck.
Iris and Stephen own a 200 sqm wooden-frame home built in 1995, on a flat 700 sqm section in Blenheim. Mid-range finish, no premium features.
Build cost at $3,200/sqm: $640,000. Plus a 30 sqm detached garage at $1,800/sqm: $54,000. Plus a 25 sqm deck and assorted paths and fencing: $35,000. Subtotal: $729,000.
Demolition allowance at 12% of build: $87,500. Suggested sum insured: $816,500, rounded up to $820,000.
Compared to the home’s current market value of $640,000, the sum insured is meaningfully higher. This is normal for NZ houses; rebuild cost (what insurance covers) and market value (what the property would sell for) are different numbers, and undershooting the sum insured leaves the household exposed if a total loss happens.
Things to keep in mind
- Sum insured replaced "total replacement" in 2013. Before 2013, NZ house policies promised to fully rebuild whatever was destroyed. After the Christchurch earthquakes, insurers shifted to a "sum insured" model where the policy pays up to the dollar amount specified. Underestimating the sum insured leaves the household paying the gap if a total loss happens.
- Rebuild cost is not market value. Market value includes land, location, and capital growth, none of which need to be rebuilt. Rebuild cost covers the structure plus demolition. In high-demand markets the rebuild figure can be lower than market value; in lower-demand markets it can be higher.
- EQC / Toka Tū Ake levy. Every house policy in NZ collects the Toka Tū Ake EQC levy on top of the premium. The levy funds the first $300,000 of natural-disaster cover (earthquake, volcanic, tsunami, landslip). The dwelling sum insured covers anything above that figure.
- Regional rebuild rates vary. Per-sqm rebuild rates run higher in Auckland and Wellington (often $3,500-$4,500/sqm for mid-range), and lower in regional areas like Whanganui or Greymouth ($2,500-$3,200/sqm). Premium-finish homes (high specification, architecturally designed) can run $5,000-$8,000/sqm in any region.
- Update annually. Construction costs in NZ have risen 30-40% since 2020. A sum insured set at policy inception five years ago is almost certainly underinsured today. Most insurers recalibrate at renewal, but it is worth checking with each renewal that the figure reflects current per-sqm rates.
NZ-specific notes
FAQs
Why is sum insured different from market value?
Insurance pays to rebuild the structure, not to replace the land or the location premium. Market value includes land (which doesn’t need rebuilding), neighbourhood premium, and capital appreciation. Sum insured covers only the dwelling, the demolition cost, and any structural extras. The two figures are usually different by 30-60%.
How do I check if my sum insured is right?
Get a registered valuer to provide a rebuild estimate (typically $700-$1,200, sometimes covered by your insurer at renewal). Or use a free online calculator like the Cordell calculator on most NZ insurer websites. The calculator on this page produces a starting figure; cross-checking with an insurer-specific tool gives a tighter range.
What is the EQC levy?
Toka Tū Ake EQC charges a small levy on every house insurance policy ($480 a year for a maxed-out $300,000 cover, plus 15% GST). The levy covers natural-disaster damage up to $300,000; private insurance picks up anything above that figure.
What if I underestimate the sum insured?
You receive only what the policy promises (the chosen sum insured), with the rest of the cost paid out of your own pocket. The Christchurch experience showed many homes rebuilt at $400,000-$600,000 above sum insured because owners had picked figures based on market value rather than rebuild cost. Building inflation makes the gap worse over time.
Does the sum insured cover the contents?
No. House (or "buildings") insurance covers the dwelling structure. Contents insurance is a separate policy covering everything that would fall out if the house were turned upside down. Most NZ households need both.
Are detached garages and sheds included?
Most policies include outbuildings up to a specified percentage of the main dwelling sum (often 10%). For a typical home with a detached double garage and a small shed, the standard percentage usually covers it; for properties with substantial outbuildings (large garage workshops, sleepouts), check whether the policy needs an extension.
How do regional differences affect the figure?
Per-sqm rebuild costs in Auckland and Wellington run 20-40% higher than regional NZ. Material delivery, labour rates, and consenting costs all contribute. A 200 sqm mid-range home in Auckland might cost $760,000 to rebuild, where the same home in Whanganui would cost $560,000. The calculator’s default figure is for mid-range build in mid-range region; adjust the per-sqm input for your specific market.
References & sources
- Toka Tū Ake EQC, "Natural disaster cover and levy". eqc.govt.nz
- CoreLogic NZ, "Cordell Construction Cost Index". corelogic.co.nz
- Consumer NZ, "House insurance reviews". consumer.org.nz
- Financial Markets Authority, "Financial product disclosure". fma.govt.nz