How do I choose a kettle, and does it affect my bills?

Kettles are the appliance people most often believe they can save money on by buying a different one, and it is the appliance where that is least true. Heating a given amount of water from a given temperature takes a fixed amount of energy; a more powerful element delivers it faster and a well-insulated one loses a little less. The saving is in the filling.

Step by step

1. Understand why wattage does not change the cost.Energy is power multiplied by time. A 3kW kettle draws more but for proportionally less time; a 2kW kettle draws less for longer. The energy to raise the same water to boiling is essentially the same, and the difference between kettles is small losses to the body and the air.
2. Do the arithmetic for one mug against your own tariff.Boiling 250ml from cold takes roughly 0.03 kWh. At an example rate of 25p per kWh — substitute yours — that is under a penny. Boiling a full 1.7 litre kettle is around 0.2 kWh, or about 5p. The difference between one mug and a full kettle is the entire saving available.
3. Buy for a water gauge you can actually read.A clear window with cup markings on the side you pour from, readable in a dim corner, is the single feature that saves the most money, because it is what stops you overfilling. Many kettles put the gauge on one side only, which is useless if it faces the wall.
4. Check the minimum fill.Kettles have a minimum below which the element is not covered. A kettle with a low minimum — enough for one mug rather than three — lets you boil what you need. This is a real specification difference and it is rarely advertised.
5. Look at the limescale filter if you are in a hard-water area.A removable mesh filter in the spout that lifts out for rinsing is what stops flakes in the tea. A fixed filter, or none, means either descaling more often or living with it. Most of England is hard or very hard water.
6. Consider variable temperature only if you will use it.Green tea at 80°C and pour-over coffee at 93°C are genuinely better than boiling water, and a variable kettle does that without waiting. If you drink black tea and instant coffee, it is a feature you will use once.
7. Weigh a rapid-boil or one-cup kettle honestly.A one-cup dispenser boils only what it dispenses, which does save energy against habitual overfilling. It also boils more slowly per litre for multiple cups, is more complex, and descaling is more awkward. It suits a single-person household more than a family.
8. Check the practical things you will handle daily.Balance when full, whether the lid opens far enough to fill and to clean inside, whether the spout pours without dribbling, and how loud it is. These are the reasons kettles get replaced, far more often than the element failing.

Tips

• Fill from a mug rather than the tap. It is the only reliable way to boil exactly what you need and it beats any kettle feature for saving.
• Descale on a schedule in a hard-water area. A scaled element takes longer to boil, which is the one way a kettle genuinely does start costing more.
• A stainless kettle with a plastic-free water path is worth seeking out if you dislike the taste new plastic kettles can give. It usually settles after a few boils in any case.
• If you make tea for a household several times a day, an insulated flask filled from one boil beats reboiling four times by a wide margin.

Common mistakes

• Buying a lower-wattage kettle to save money — It takes the same energy and longer to do it. The only thing a lower wattage does is make you wait, and on a weak circuit it slightly reduces peak draw.
• Reboiling water repeatedly — Every reboil costs the same as a fresh boil of that water from wherever it has cooled to. Two reboils a day is roughly a full kettle's worth of energy wasted.
• Ignoring descaling — Scale insulates the element from the water, so the kettle runs longer to reach the same temperature and the element runs hotter, which shortens its life.

Questions people ask