Boiling the kettle costs more than you think

You flick on the kettle, walk away, and return to a jug of boiling water. But how much did that just cost you? Canstar Blue has crunched the numbers and found that the humble kettle can create a surprising strain on your electricity bill, especially when it’s used several times a day.

How much does it cost to boil the kettle?

Boiling an electric kettle costs 4 to 5 cents, depending on the size of the kettle and the rate you pay on electricity. Most commercial kettles range in size from 1.5L to 1.8L, with the larger kettles intuitively consuming more electricity. Kettle power will also vary between 2000W and 2400W, however this is much less important as you will soon see below.

To calculate the real running cost of a kettle, we must first work out how long a kettle will take to boil given its size and power. The below table assumes the kettle is filled to its maximum recommended capacity and the beginning water temperature is 20°C.

  1.5L 1.6L 1.7L 1.8L
2000W 4m 12s 4m 29s 4m 46s 5m 2s
2100W 4m 0s 4m 16s 4m 32s 4m 48s
2200W 3m 49s 4m 4s 4m 19s 4m 35s
2300W 3m 39s 3m 53s 4m 8s 4m 23s
2400W 3m 30s 3m 44s 3m 58s 4m 12s

The wattage of a kettle refers to how much energy it will consume within one hour. So a 2200W, for example, will consume 2200W in one hour (or 2200Wh/2.2kWh). However, as we calculated above, it only takes 3-5 minutes to boil a kettle, meaning it’s only consuming a fraction of electricity.

To elaborate, let’s take a 1.7L, 2200W kettle. When full, this kettle will take 4 minutes, 19 seconds to boil. In that period of time, the kettle will use 158.3Wh or 0.1583kWh of electricity. If you are charged 28.7c/kWh for electricity, then this means that boiling the kettle has just cost you 4.55c.

Kettle-boiling costs explained

  1.5L 1.6L 1.7L 1.8L
2000W 4.02c 4.29c 4.55c 4.81c
2100W 4.02c 4.28c 4.55c 4.82c
2200W 4.01c 4.28c 4.55c 4.82c
2300W 4.02c 4.28c 4.54c 4.82c
2400W 4.02c 4.28c 4.55c 4.82c

Assuming an electricity usage rate of 28.7c/kWh

The table above shows that the cost of boiling the kettle increases with size, but not with power. That’s because a more powerful kettle will boil water faster, so while it consumes more electricity at any one moment, this is negated by the kettles reduced operating time.

Annual kettle running costs:

A silver echidna might sound like a small price to pay, but the costs quickly add up. Keep in mind the kettle is likely used more than once per day – perhaps not just by you, but by those you share your home with. In the table below, we calculated what your kettle might be costing you each year, depending on its size and how often it is used each day.

Annual cost of boiling the kettle

  1/day 2/day 3/day 4/day 5/day 10/day
1.5L $14.67 $29.34 $44.01 $58.68 $73.35 $146.70
1.6L $15.62 $31.24 $46.86 $62.48 $78.10 $156.20
1.7L $16.61 $33.22 $49.83 $66.44 $83.05 $166.10
1.8L $17.59 $35.18 $52.77 $70.36 $87.95 $175.90

Assumes kettle is used 365 days a year

How can I reduce the cost of my kettle?

There is no such thing as an energy efficient kettle, meaning the only way to save money on your kettle is to adjust your habits. But that doesn’t necessarily mean you have to reduce your kettle usage.

The above tables assumed that a kettle was filled to its recommended maximum. If however, the kettle were say only half filled, it would take approximately half the time to boil and therefore only consume half the electricity. So if you’re pulling all the stops to minimise your energy bill, only fill the kettle with as much water as you need at that moment.

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