THE FIELD NOTES / GUIDE

What does your appliance really use?

A meter reading beats a guess.

The wattage on a label may describe rated power, not an appliance’s average consumption. Refrigerators and dehumidifiers cycle on and off; a single power reading will not describe a full day.

Use a representative measurement

Where suitable for the appliance and socket rating, a plug-in energy meter can measure kWh over time. Record the duration and conditions. Divide total kWh by measured days to estimate daily use. Hardwired equipment may require a qualified professional or existing meter data.

Keep the units straight

1,000 Wh is 1 kWh. A hypothetical appliance averaging 300 W for 4 hours uses 1.2 kWh. At 0.25 currency units per kWh, that costs 0.30 per day, or 9.00 over 30 days.

Compare fairly

Use the same time period and tariff for both usage patterns. Weather, occupancy and settings can affect consumption, so an estimated difference is not a guaranteed saving. Fixed charges usually remain even when an appliance uses less.

Sources and next steps

EIA: measuring electricity — background reference, not an endorsement.