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

A solo NZ developer. 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 it stays free

• Display advertising via Google AdSense. Ads are kept to a small number of unobtrusive units, out of the way of the actual calculator.
• 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. The page uses Umami, a privacy-focused, cookie-free analytics tool, only to count which pages people visit and where they came from. There is no individual tracking, no fingerprinting, and no third-party ad-tech.

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. No cookies are set by this site.

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.