Understand your estimate
How to use this result
Use complete-boil electricity or an explicitly steady power/time estimate for the same water task. Add keep-warm electricity only outside that boundary; the optional water-volume field describes the task and does not rescale measured energy.
Method reviewed · Calculation methods · Evidence and source policy
Find the right inputs
Complete-boil source
Measured kWh/boil, or input W and minutes
Keep water volume, starting temperature and endpoint comparable.
Routine
Boils/day and chosen use days
Use the number of complete boils, including actual reboiling where relevant.
Separate warming
Average W and hours outside the boil measurement
Do not add warming already captured in the energy reading.
The calculation
Boiling energy = complete-boil kWh × boils/day × use days. Add separate keep-warm W ÷ 1,000 × warming hours/day × days. Apply the tariff to the sum.
A worked arithmetic example
Illustrative arithmetic: 0.1 kWh per complete boil, four boils/day and 365 use days give 146 kWh and $29.20 at $0.20/kWh. Separate 20 W warming for two hours/day adds 14.6 kWh and $2.92.
What the estimate can tell you
A more powerful kettle may finish a task sooner; watts alone do not establish complete-boil energy. The numerical example is not a measured product or a claim that every litre requires 0.1 kWh.
Questions about this calculation
Does entering litres change the measured kWh?
No. It provides task context and kWh/litre for that reading. A larger volume needs its own measured or documented energy rather than an automatic adjustment.
How do I average several boils?
Divide accumulated energy for comparable complete boils by their count. Preserve the individual task conditions and avoid including unrelated keep-warm periods without identifying them.