The overall Which? test score is made up of the following star ratings, all determined by our rigorous lab tests.
How we test speed
How quickly the kettle boils one litre of water.
How we test water window/gauge
We rate how easy it is to see the water level.
How we test cleaning
We check the outer surfaces of kettles for dirt traps and rate whether they are quick to show fingermarks and smudges.
How we test quietness
How noisy the kettle is when boiling and how irritating the sound is. Quieter and less obtrusive kettles get higher star ratings.
How we test overboil time
How quickly the kettle turns itself off after reaching boiling point, saving time and electricity. Better kettles have shorter overboil times, and the best switch off immediately.
How we test minimum fill
How much water you need to fill the kettle with to be able to use it - better kettles have lower minimum fill amounts and clearly display the minimum level.
How we test limescale filter
How effective the filter is at trapping limescale and how easy it is to remove, clean and replace it.
How we test filling
We rate the ease of filling the kettle, both through the lid opening and the spout where possible.
How we test handle
Five star kettles have a handle that is well designed and comfortable to hold, suiting all hand sizes.
How we test handling
We rate the weight and balance of the kettle, when full and empty, and assess the ease of returning it to its base.
