About this calculator
Powerbill.co.nz is a free tool that estimates your monthly New Zealand power bill, broken down by appliance, using current MBIE regional pricing. It has no signup, no email capture, no behavioural tracking, no AI chat widget, and no popovers asking you to subscribe to a newsletter you do not want.
It exists because the alternatives are either built by power retailers (with the obvious conflict of interest), require uploading a smart-meter export (most NZ households cannot easily get one), or are American calculators using American electricity rates and US heating habits. None of those produce a useful number for someone in Christchurch trying to work out why their July bill was $640.
Who built this
Powerbill.co.nz is written and maintained by Jason Webb, a software developer in Christchurch, New Zealand. Every guide on this site carries his byline, and the email below reaches him directly.
Jason Webb is a New Zealand software developer who built Powerbill.co.nz after trying to work out why a Christchurch winter bill had doubled and finding every available calculator was either run by a power retailer or priced in US cents. He maintains the appliance and regional pricing data himself, updating it each quarter when MBIE publishes.
The calculator runs entirely in your browser and does not send any of your inputs to a server, ever. The URL sharing feature works by encoding everything into the query string, which is why shareable links are long.
How we source and check our numbers
Every figure on this site traces back to a named source, and the sources are the ones a New Zealand household can check for themselves:
- Regional pricing comes from the MBIE Quarterly Survey of Domestic Electricity Prices (QSDEP), the government's own retail price series. We use the published figure for each centre rather than a national average, which is why a Balclutha estimate differs from a Wellington one.
- Network and fixed charges come from Electricity Authority network data, split into the low-user and standard tariffs so the daily charge is matched to the right per-unit rate rather than blended into it.
- Appliance wattages come from Consumer NZ, EECA's Genless programme, and manufacturer rating plates, cross-checked against reader-supplied meter readings where we have them.
- Heat pump efficiency uses winter COP figures by climate zone, not the headline COP printed on the box, because the box figure is measured at a mild outdoor temperature that a Southland July does not resemble.
Where a number is an estimate rather than a measurement, we say so on the page. Where a figure has changed since we published, the guide carries an updated date. We have no commercial relationship with any power retailer, and nothing on this site is written or reviewed by one.
How it stays free
- Display advertising. Ads are kept to a small number of unobtrusive units, out of the way of the actual calculator. The privacy policy names the network currently serving them and what it collects.
- The Powerswitch link on the calculator is not affiliate. We send you to Powerswitch because it is Consumer NZ's free, independent comparison tool, and because comparing retailers periodically is genuinely the highest-value thing most NZ households can do about their bill. We earn nothing from it.
Privacy
The calculator runs entirely client-side. Your appliance ticks, slider positions, and region selection do not leave your browser, and we never record what you enter into it. There is no account, no email capture, and no way for us to identify you personally.
The site does use analytics to see which pages get read, and it carries display advertising, some of which sets cookies. Rather than summarise that here and let the two accounts drift apart, the privacy policy sets out exactly which services are running, what each one collects, and how to opt out of them.
If you press Save as baseline to use the Compare feature, a single entry is stored in your browser's localStorage under the key powerbill.snapshotA. It contains the same URL-encoded state as a shareable link. Nothing is sent to a server and clearing your browser data removes it.
Update cadence
The MBIE Quarterly Survey of Domestic Electricity Prices (QSDEP) is released on the 15th of February, May, August and November each year. The regional pricing data on this site is updated within a week of each release. The data file in use is shown at the bottom of the calculator with its last-updated date.
Appliance wattages and other reference data (heat-pump COP ranges, BRANZ heat-loss figures, EECA grant percentages, retailer plan structures) are reviewed annually or when we notice they have shifted.
Mistakes & corrections
If you spot a wattage that is wrong, a region we are missing, or a calculation that does not match your actual bill, please email [email protected]. Real bills with real retailers are particularly useful as ground truth.
The methodology page explains how the calculations work in detail, including assumptions and known limitations.