Microwave magnetron efficiency is around 65%. Since a kettle turns electricity directly into heat, it’s basically 100% efficient.
A caveat is that microwaves will heat water directly and won’t lose as much to its surroundings. This is similar to why induction stoves are more efficient; they’re less efficient on paper than direct electric heating or burning gas, but they heat the thing you want in a more direct way.
Even so, a microwave isn’t great for this task. If you’re short on space and don’t want even a small travel kettle, I can see why you’d take this option. Otherwise, no.
Microwave magnetron efficiency is around 65%. Since a kettle turns electricity directly into heat, it’s basically 100% efficient.
A caveat is that microwaves will heat water directly and won’t lose as much to its surroundings. This is similar to why induction stoves are more efficient; they’re less efficient on paper than direct electric heating or burning gas, but they heat the thing you want in a more direct way.
Even so, a microwave isn’t great for this task. If you’re short on space and don’t want even a small travel kettle, I can see why you’d take this option. Otherwise, no.