The short answer
Rank the appliances by kWh over the same period, then apply the relevant tariff. High watts alone do not identify the largest bill contributor: a brief powerful task can use less energy than a smaller draw repeated for many hours. Keep household-planner rows non-overlapping and include each appliance’s routine.
Rank energy over the same period
The appliances that cost your household most are those using the most charged electricity over the period you are comparing. High watts alone do not establish that ranking: a short, powerful task can use less energy than a modest draw repeated for many hours.
Start with a month or another clearly defined period. Estimate or measure each appliance’s kWh for that period, then apply the relevant electricity price. This follows the power-and-time calculation described by Reading Municipal Light Department.
An illustrative household ranking
The following is an illustrative 30-day scenario at £0.28 per kWh, not a national average or a list of typical appliance consumption. Each row makes its own usage assumption explicit.
| Appliance | Assumption for this example | Period kWh | Cost |
|---|---|---|---|
| Electric heater | 1.5 kW for 5 hours on each of 30 days | 225 | £63.00 |
| Dehumidifier | Measured average of 2 kWh per day, repeated for 30 days | 60 | £16.80 |
| Fridge | Measured average of 0.95 kWh per day, repeated for 30 days | 28.5 | £7.98 |
| Oven | 1.2 measured kWh per complete meal, 12 meals | 14.4 | £4.03 |
| Television | Constant 80 W for 4 hours on each day | 9.6 | £2.69 |
| Kettle | Constant 2 kW for 6 minutes on each day | 6 | £1.68 |
The kettle has the largest input rating of several rows, yet its short use time gives it a smaller period total. Changing the heating routine or the number of meals can change the ranking.
Match the tool to the source
Use the watts-and-hours calculator for a suitable input-power estimate or a complete-day measurement. Use a cycle-based tool for a compatible washer, dryer or dishwasher figure and your own frequency.
An annual label figure can support an annual comparison. Dividing it into a monthly average does not turn it into a measurement for a particular cold or warm month. Record whether each row uses a label, a measurement or a constant-power assumption.
Avoid counting the same energy twice
A whole-home meter includes several loads. Its daily total cannot be attributed to one appliance without separating other consumption. A measured complete cooking task already includes the preheating and batches captured in that task.
Check whether hot water, auxiliary equipment or standby use is inside each source’s boundary. A useful ranking uses compatible boundaries and one occurrence of each energy component.
Use the ranking to choose the next measurement
Focus first on large, uncertain rows that you can reasonably investigate. Repeat measurements under ordinary use and keep the programme, setting and weather notes with them. Read the measurement guide for the distinction between instantaneous watts and accumulated energy.
A cost ranking helps explain a bill. It does not establish how much of an essential task can be eliminated, or justify changing heating, cooling or moisture-control settings solely to improve the ranking.