How to Check Appliance Power Ratings and Calculate Running Costs

To estimate what an appliance costs to run, find its power rating in watts (on the rating label or in the product specifications), convert that to kilowatt-hours (kWh) by multiplying kilowatts by hours of use, then multiply by your electricity unit price. For example, a 2,000 W appliance used 1 hour a day uses 2 kWh daily; at 30p per kWh that is about 60p a day. This works for any mains appliance where you know the wattage and can estimate usage hours. For vehicles and larger comparisons, Sust-it's databases and cost calculators cover electricals and vehicles, including running costs, fuel consumption and CO2 emissions.

Step 1: Find the power rating

Check these sources in order:

1. Rating label or plate — usually on the back, base or inside a door. Look for "W", "watts" or "kW".
2. Product specifications — manufacturer page, manual or retailer listing.
3. Energy label — for large appliances, annual energy use in kWh is often shown, which you can divide by 365 for a daily average.

Record the figure in watts. If it says kW, multiply by 1,000 (1.5 kW = 1,500 W).

Watch for range ratings

Some appliances list a range (e.g. 1,000–2,000 W) because power varies by setting. Use the setting you actually use most, or calculate both ends to see the spread.

Step 2: Convert watts to kilowatt-hours

The formula:

kWh = (watts ÷ 1,000) × hours used

For appliances that cycle on and off (fridges, ovens, heaters with thermostats), the label wattage is peak draw, not average. Use the annual kWh figure where available, or treat the result as an upper bound.

Step 3: Multiply by your electricity unit price

Running cost = kWh × price per kWh

Check your bill or tariff for the unit rate. Using the table above at 30p per kWh:

• Kettle: 0.75 kWh × 30p = 22.5p per day
• LED bulb: 0.05 kWh × 30p = 1.5p per day
• Fan heater: 4 kWh × 30p = £1.20 per day
• Fridge-freezer: 3.6 kWh × 30p = about £1.08 per day

Repeat with your own rate; the ranking of appliances usually stays similar even when prices change.

Step 4: Compare models before buying

Use the same method on candidate models so the comparison is like-for-like:

• Compare annual kWh from energy labels where both products have them.
• For products without labels, compare wattage at the same setting and multiply by the same usage hours.
• Check whether the rating is peak or average — a lower peak with a thermostat may still cost more over a year than a higher-rated appliance that runs briefly.

Sust-it's appliance and technology databases list energy usage and running costs across categories including refrigeration, washing and drying, dishwashers, cookers, small appliances, televisions, computers and printers, so you can compare before buying.

Step 5: Account for standby and real-world use

Label ratings rarely capture everything:

• Standby power — many devices draw 0.5–5 W when "off". A device at 3 W standby for 20 hours a day uses 0.06 kWh daily, roughly 1.8p at 30p per kWh — small per device but adds up across a home.
• Usage patterns — a kettle's 3,000 W matters little because it runs for minutes; a 150 W fridge matters more because it runs constantly. Always pair the rating with realistic hours.
• Heating and cooling — these usually dominate bills. Sust-it's heating and cooling calculators and price comparisons (halogen, fan, convector, ceramic, oil-filled and panel heaters) help compare options on running cost rather than purchase price alone.

Quick checklist

• [ ] Wattage found on label or specs
• [ ] Hours per day or week estimated realistically
• [ ] kWh calculated (watts ÷ 1,000 × hours)
• [ ] Unit price taken from your tariff
• [ ] Standby and cycling behaviour considered
• [ ] Same method applied to alternative models

Once you have running costs for your main appliances, target the largest contributors first — usually heating, cooling, wet appliances and refrigeration — before worrying about low-wattage items.