There are often a few key reasons why your power bill might be creeping up higher than expected. It might be because you're spending more time at home, purchased new appliances, or your heat pump has been working overtime.

If you're wondering where to start when diagnosing a high power bill, we've pulled together a few ideas below. Plus, there are some bonus ways to help you try and avoid billing surprises in the future.

What causes a high power bill?

1. Your Billing Period Was Longer

The typical number of days billed each month for Mercury customers is 30. However, this may vary due to a couple of factors. Public holidays affect when your bill is issued, so a few days more or less could make the total amount due higher or lower than previously. For example, the billing period from December through to January is about five to eight days longer due to the public holidays.

2. Something Has Changed At Home
Adding a new element to your lifestyle mix can sometimes impact the number at the bottom of your bill. You might have a new baby, more people living in your home, or new appliances like a second refrigerator. Or, additional living spaces could be in use if someone is now working from home. These factors can cause an increase in hot water use, laundry costs, and heating and cooling costs.

3. Your Rate Could Have Changed
Changes or increases in energy rates can affect the total amount due. This could be due to prices changing along the electricity supply chain, a process which is reviewed by all companies each year. You can learn more about what goes into your electricity bill and The Electricity Authority Price Breakdown here.

4. A Change In Seasons And Usage
When a good old Kiwi summer rolls around, hot and humid days mean you may run the air conditioner more frequently. On the flip side, cooler temperatures mean your heating appliances could be put in the hard yards in winter. Regardless, air conditioning, dehumidifiers, swimming pools/pumps, and spa pools would increase energy use.

5. Actual Or Estimated Meter Readings
We try to be as accurate as possible when we estimate meter readings; however, a few factors can lead to under or overestimations. These could be changes in lifestyle at home or a change in season. Other reasons could be that it's a new property for you, we don't have data on your usage yet, or we don't have access to your meter. Get more info on what is involved in an estimated meter reading here.


So, what can you do to avoid a high bill?

1. First, Keep Track Of Your Usage
The power is literally at your fingertips with our energy-tracking tools. Smart meter customers can drill down to see their monthly, daily, or hourly usage. Get up close and personal with your usage graphs in My Account, or head to our app and choose 'usage' from the heading options.

2. Master Energy Efficiency
Once you have a clear idea of your energy habits, you'll be equipped to tackle any inefficiencies in your home. One way to start is by making your home 'energy-fit' or getting clued up on sneaky appliances that are draining your power. There are plenty of ways to master energy efficiency on our blog.

3. Avoid Estimated Readings
If you have an older meter that must be read manually, make sure you're getting an actual reading regularly. This often involves a Meter Reader visiting your property to take a reading, but you can also provide a customer reading yourself. Go to My Account, or head over to 'Bills' and tap 'Meter Reading' in our app. Still got questions? Everything you need to know about your billing with Mercury can be found here.


The information provided in this article is of a general nature and not intended to be a substitute for personalised, professional advice. Mercury recommends that you always seek appropriate advice from a qualified professional to suit your individual circumstances. Links to external, non-Mercury websites are provided as a reference only, and do not imply a partnership or endorsement of their content.