Renovation budget calculator: built from the parts, with the working shown.
No magic rate per square metre. Tick the work you are actually planning, and this calculator builds a labour component from real published trade pay bands, applies a charge-out multiple you can see and change, adds the materials allowance you set, then contingency, consent fees and professional fees as their own lines. Every step is printed underneath the answer.
Photography commissioned — plate reserved · July 2026
The calculator
Build the budget.
How it works
The method, so you can check it or reject it.
Four inputs are published data, two are this site’s judgement, and four are yours. Knowing which is which is the whole point.
The arithmetic, in order
- Labour hours. Each scope item carries an hours allowance — this site’s judgement — multiplied by your adjustment factor.
- Wage cost. Hours × a blended hourly rate for that item’s trade mix. The low end uses each trade’s published median; the high end uses the upper-middle of its published band. Both ends are real dataset values, so the spread comes from the data rather than from a guess.
- Charge-out. Wage cost × the multiple, turning what people are paid into what a business invoices.
- Materials. Your figure, added as-is.
- Contingency. Your percentage, applied to labour plus materials.
- GST. 15% on labour, materials and contingency, only if you tick it.
- Consent and professional fees. Your figures, added last and not re-taxed.
What it deliberately does not do
- It does not quote. Nobody has offered you the number it produces.
- It does not know your site: access, parking, scaffolding, storeys, ground conditions, protected trees, or how far the truck has to reverse.
- It does not price a finish level. The same bathroom in the same hours can carry a $6,000 materials bill or a $40,000 one, which is why materials is your input.
- It does not include demolition disposal, temporary accommodation, storage, or the cost of not having a kitchen for six weeks — all of which are real and all of which people forget.
- It does not include finance costs, and on a long renovation those are not trivial.
Why an older house needs a bigger contingency
Because renovation is the only kind of construction where you buy before you look. A new build has unknowns in the ground; a renovation has them in every wall. The things that turn up in Auckland pre-1980s houses often enough to plan for: framing that is undersized or unbraced by current standards, borer, rot around wet areas and at the base of cladding, wiring that has to be replaced rather than extended, drainage that does not go where the plan says, materials that need specialist handling and disposal, and previous work that was never consented and now has to be resolved. Ten per cent covers surprises. Twenty per cent covers a surprise that changes the sequence.
| Trade | Median | Upper-middle | Published band |
|---|---|---|---|
| Cabinet maker | $33.65 | $41.35 | $24.04–$49.04 |
| Carpenter | $31.25 | $40.38 | $24.04–$49.52 |
| Electrician | $41.35 | $51.44 | $24.04–$63.94 |
| Plumber | $35.10 | $43.75 | $24.04–$51.92 |
| Wall and floor tiler | $32.21 | $40.38 | $24.04–$50.00 |
| Drainlayer | $37.98 | $47.12 | $24.04–$57.69 |
| Plasterer | $30.77 | $38.46 | $24.04–$48.56 |
| Painter and decorator | $29.81 | $36.06 | $24.04–$45.19 |
| Glazier | $32.21 | $38.46 | $24.04–$47.12 |
| Roofer | $31.73 | $40.38 | $24.04–$51.92 |
The pay you see here is your pay before tax. When an employer pays you, Inland Revenue (IR) collects a percentage of that income. Learn more about income tax on the IR website
Tertiary Education Commission — Tahatū Career Navigator · retrieved 2026-07-30
| Scope item | Hours |
|---|---|
| Kitchen — new cabinetry and appliances, same layout, same services | 90 |
| Kitchen — relocated sink, new layout, new tiling | 155 |
| Bathroom — full refit in the same footprint | 110 |
| Bathroom — a new one where there was not one | 170 |
| Laundry — new or relocated | 45 |
| Remove a non-structural internal wall, and make good | 18 |
| Remove a structural wall, beam in, and make good | 60 |
| One new window or door opening in an exterior wall | 24 |
| Single-storey extension, around 20 m² | 430 |
| Strip and reline one room, stopped and painted | 42 |
| Repaint the interior of a three-bedroom house | 120 |
| Tile or hard-floor one wet area and a hallway | 38 |
| Re-roof a single-storey house | 95 |
| Reclad one elevation, including underlay and flashings | 185 |
| Timber deck, around 20 m² | 72 |
| Rewire a three-bedroom house | 85 |
| Alter or extend the drainage | 40 |
There is no published New Zealand dataset of labour hours per renovation scope. These are this site’s allowances for a typical Auckland job, exposed rather than hidden inside a rate, and adjustable in the calculator above.
Judgement — this site, stated as judgement per CONTRACT §4.5 · July 2026
Questions people actually ask
How much should I budget for contingency on a renovation?
10 to 20% of the build cost is the normal range on an existing building, and the reason is not sloppiness — it is that you are buying a decision about something nobody has seen yet. Until the linings come off, the framing condition, the wiring, the drainage and whatever the last owner did are genuinely unknown. Older houses sit at the top of that range: pre-1980s Auckland houses can turn up borer, rot behind wet areas, undersized or unbraced framing, materials that need specialist handling, and previous work that was never consented. On a new build the unknowns are in the ground; on a renovation they are in the walls.
Why does this calculator not just use a price per square metre?
Because no free official New Zealand source publishes one for renovation work, and the closest thing that exists cannot be turned into one. Stats NZ publishes the declared value of dwelling alteration consents, but that series carries no floor area, so a dollars-per-square-metre figure literally cannot be computed from it. Building the number up from scope and hours is more work and much closer to how a builder actually prices a job. The full explanation.
What is the charge-out multiple, and is 2.2 right?
It is the gap between what a tradesperson is paid and what a business invoices for their time. It covers holiday pay, ACC and KiwiSaver, the hours that are not billable, vehicles, tools, insurance, administration, rework and margin. 2.2 before GST is this site’s judgement and it is deliberately an input rather than a constant, because it varies by trade, by business size and by how the job is contracted. If you have a real quote and a real hours figure, divide one by the other and use your own number.
Where do the labour hours come from?
They are this site’s judgement, stated as judgement, printed in the working, and adjustable with a single multiplier. There is no published dataset of labour hours per renovation scope item in New Zealand, so the honest options were to make them visible and changeable, or to hide them inside a per-square-metre rate and pretend. This site chose the first.
Does the range include GST?
Only if you tick the box. It is off by default so you can compare against a quote given excluding GST, which is common in the trade. When it is on, GST at 15% is applied to labour, materials and contingency. Consent and professional fees are added afterwards and are not re-taxed, because you should enter those as you were quoted them.
Why are consent fees blank?
Because Auckland Council sets them, reviews them, and publishes them — and a council fee copied onto a third-party page is a number that will be wrong eventually while still looking current. Read the live schedule at Auckland Council building consent fees and charges and type the figure in. What the consent cost is made of.
Can I use this to argue a builder’s quote down?
Please do not. It is a planning model built on published wage data and stated assumptions, not a market price, and it knows nothing about your access, your site, your programme or your finish level. What it is genuinely useful for is finding out which line is driving your budget, and having a specific conversation — “your labour looks like about 300 hours, is that right?” is a much better question than “that seems expensive”.
What it costs, with sources
The published Auckland market context, and why a renovation price per square metre cannot be computed.
Consent time and cost
What to put in the consent-fees line, and what the consent process is actually made of.
Renovation return
Once you have a spend, model what it does to rent, yield and payback.
Pay data. Hourly rates in this calculator come from Tertiary Education Commission — Tahatū Career Navigator, licensed CC BY 4.0, retrieved 2026-07-30. The pay you see here is your pay before tax. When an employer pays you, Inland Revenue (IR) collects a percentage of that income. Learn more about income tax on the IR website — Inland Revenue on income tax. That is pay, not a charge-out rate: what a business invoices includes overhead, non-productive time, tools, vehicles, insurance, administration and margin. This calculator makes that gap an input you can see and change.