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Boiling 1 liter of room-temperature water in a 1,500-watt electric kettle uses about 0.10 kWh and costs roughly 1.7 cents at a US residential average of about 17 cents per kWh, the series published in the US Energy Information Administration's published average retail price of electricity to residential customers. A single 8-ounce mug is about 0.03 kWh, or half a cent. A household boiling five times a day uses roughly 12 to 18 kWh a year for tea and coffee water — about $2 to $3 annually at the average rate. Kettles have high wattage and very short run times, which is why the running cost is trivial even though the draw is among the largest of any countertop appliance.
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Why the Number Is Fixed by Physics
Heating water takes a specific amount of energy regardless of the appliance. Raising 1 liter from 68 degrees F to boiling requires about 0.097 kWh of energy delivered into the water. No kettle can beat that; they differ only in how much of the electricity they draw ends up in the water rather than in the air, the countertop and the kettle body.
An immersed element in an electric kettle is roughly 80 percent efficient — the heat has nowhere to go except the water. So a real 1-liter boil consumes about 0.12 kWh at the wall. A radiant electric burner heating a pot is roughly 40 to 55 percent efficient because much of the heat radiates past the pot, and an open gas flame is about 40 percent efficient though gas is cheaper per unit of energy.
Cost per Boil
| Volume | Energy at the wall | Time at 1,500 W | Cost at 17 cents per kWh |
|---|---|---|---|
| 1 mug (8 oz / 240 ml) | About 0.03 kWh | About 1 minute | About 0.5 cents |
| 2 mugs (16 oz) | About 0.06 kWh | About 2 minutes | About 1 cent |
| 1 liter | About 0.12 kWh | About 4 minutes | About 2 cents |
| Full 1.7 L kettle | About 0.20 kWh | About 6 to 7 minutes | About 3.4 cents |
| Full kettle, 5x daily, one year | About 365 kWh | — | About $62 |
| One mug, 5x daily, one year | About 55 kWh | — | About $9 |
That last pair is the only meaningful saving available: filling to what you actually need rather than to the top.
Regional Variation
Your rate matters more than your kettle. Approximate cost of one full 1.7-liter boil (0.20 kWh) using EIA residential averages, as of 2026:
| Region | Approx. rate per kWh | Cost per full boil | Annual, 5 boils a day |
|---|---|---|---|
| Hawaii | About 42 cents | 8.4 cents | About $153 |
| California | About 32 cents | 6.4 cents | About $117 |
| Northeast | About 27 to 31 cents | 5.4 to 6.2 cents | $99 to $113 |
| US average | About 17 cents | 3.4 cents | About $62 |
| Southeast | About 12 to 14 cents | 2.4 to 2.8 cents | $44 to $51 |
| Pacific Northwest | About 11 to 13 cents | 2.2 to 2.6 cents | $40 to $47 |
Figures are 2026 averages and indicative only. If your utility bills time-of-use, an evening boil can cost two to three times an overnight one; check your own bill for the rate and peak window.
What Raises Your Cost
- Overfilling. The dominant variable by a wide margin. Fill to the mug markings, not the max line.
- Keep-warm. Holding 1.7 liters at 175 degrees F cycles the element repeatedly. Leaving keep-warm on for an hour can use more energy than the original boil.
- Reboiling. Water that has cooled from 200 to 150 degrees F still needs most of the energy again. Boil what you will use within a few minutes.
- Limescale. An insulating layer on the element forces longer run times, adds a few percent to consumption, and is the main cause of premature element failure.
- Starting temperature. Cold-tap water in a northern winter can arrive at 40 degrees F rather than 68, which adds roughly a third to the energy needed.
- Rated wattage. Counterintuitively, this does not change energy used much — a 1,000-watt kettle simply takes longer to deliver the same energy, and loses slightly more to standing heat loss while it does.
Is It Worth Optimizing?
Honestly, barely. A kettle is roughly 1 to 2 percent of a typical household electricity bill, which averages around 900 kWh a month nationally. Descale it, do not leave keep-warm running, and fill it to what you need — those three habits capture nearly all the available saving and cost nothing. Descaling matters most where the water is hard: the USGS notes that heating hard water forms solid calcium carbonate deposits that cut efficiency and shorten equipment life.
Where the choice genuinely matters is speed and control, not cost. Variable-temperature kettles that hold 175 degrees F for green tea or 205 degrees F for pour-over coffee are worth the money for what they do, not what they save.
Related: how many watts an electric kettle uses for the spec detail, how to descale an electric kettle with vinegar, and how long an electric kettle lasts. If you are replacing one, our best electric kettle picks rank on owner-reported longevity and element quality, and how to choose a coffee maker covers where a kettle fits in a pour-over setup.