How to use these examples
Every number below is an illustrative teaching value, not a site measurement, product benchmark, or typical-use claim. Use each example to choose an input method, then replace its label or meter details, dates, and rate with information from your own appliance.
Each cost covers only the stated electricity use at the example rate. Fixed bill charges and taxes are excluded. Keep unrounded costs when multiplying by repeat uses, then round the final amount.
1. Kettle: time one heating cycle
The record pairs a fictional 1,500 W label with one 4-minute heating period. Convert the timed interval before multiplying: 1,500 / 1,000 x (4 / 60) = 0.10 kWh. At a rate of 0.27 per kWh, that one session costs 0.10 x 0.27 = 0.027, displayed as 0.03. If the rate is in dollars, the result is 0.03 dollars; use the equivalent unit for another currency.
What the timer defines: the result covers one heating period. It excludes a second boil, standby use, and any time after the kettle switches off. Multiply only by comparable heating periods.
2. Dehumidifier: meter three named humid days
In this fictional log, a plug-in monitor is reset to zero at 00:00 on June 1 and read at 00:00 on June 4. It records 4.86 kWh for the dehumidifier alone across June 1, 2, and 3, all humid days in the example. At a rate of 0.19 per kWh, the three-day period costs 4.86 x 0.19 = 0.9234, displayed as 0.92. No wattage estimate is needed because the monitor already accumulated energy.
When not to scale it: the reading excludes dry days and other devices. Do not multiply it across a month until the humidity setting, water-removal cycle, and operating hours are comparable.
The smart-plug measurement workflow explains how to set the start, stop, appliance boundary, and excluded periods before using a monitor total.
3. Chest freezer: start with the annual label
A fictional chest-freezer energy label states 310 kWh per year. At a rate of 0.25 per kWh, the annual usage cost is 310 x 0.25 = 77.50. To compare a shorter period without inventing runtime, its average 30-day share is 310 x 30 / 365 = 25.479... kWh, costing 6.37 after final rounding.
What the conversion does not claim: the 30-day value is an average share of an annual label, not a measured calendar month. Room temperature, loading, defrost behavior, and door openings can make a real month differ.
The refrigerator cost guide compares this annual-label path with a complete measured day and explains why nameplate watts rank below both.
4. Washer: divide four comparable cycles
A fictional log totals four washer cycles using the same program, water-temperature setting, and similar load size, with 2.64 kWh measured at the washer's electricity input. Divide the grouped reading to find the average: 2.64 / 4 = 0.66 kWh per cycle. At a rate of 0.22 per kWh, the average matching cycle costs 0.66 x 0.22 = 0.1452, displayed as 0.15.
Which cycles belong: group different wash settings, load sizes, or drying cycles separately when estimating one repeatable wash. Hot washes can form their own comparison group. This reading excludes energy used by a separate household water heater and any standby time between the recorded cycles. It is not the total cost of doing laundry.
For a second cycle-based decision, the dryer cost-per-load guide carries one load through a recorded repeat count and a 30-day example.
Choose the calculator from the input that survives the check
Use the Appliance Electricity Cost Calculator when labeled watts and a timed duration remain the strongest inputs. Use the kWh to Cost Calculator when you already have annual, measured-period, or per-cycle kWh. Keep the period with either result. If the selected-use result differs from the amount due on a statement, use the bill-difference guide without forcing the appliance calculation to equal the full bill.