❓ Frequently Asked Questions
How is electricity cost calculated?
Electricity cost is calculated using the formula: (Watts × Hours used per day) ÷ 1,000 = daily kWh. You then multiply the daily kWh by your electricity tariff rate (price per kWh) to get the daily cost. For monthly costs, multiply by 30 days, and for annual costs, multiply by 365 days. This gives you an accurate estimate of how much any appliance costs to run over time.
What is standby power and why does it matter?
Standby power (also called "vampire power" or "phantom load") is the electricity consumed by devices when they are switched off but still plugged into the mains. Common culprits include TVs, game consoles, phone chargers, and microwaves. The Energy Saving Trust estimates that the average UK household spends £65 per year on standby power alone. Over a decade, that's £650 wasted on devices doing nothing.
What is a kWh and how does it relate to my bill?
A kilowatt-hour (kWh) is the standard unit of energy used by electricity suppliers to measure consumption. One kWh equals using 1,000 watts of power for one hour. For example, a 2,000W kettle running for 30 minutes uses 1 kWh. Your electricity bill charges you per kWh consumed, so understanding this unit helps you predict and control your energy spending.
How do I find the wattage of my appliances?
You can find appliance wattage in several ways: check the label or sticker on the back or bottom of the device, look in the user manual, search the manufacturer's website for the model specifications, or use a plug-in energy monitor (available from £10–£25). If only amps and volts are listed, multiply them together to get watts (Watts = Volts × Amps).
What is the average electricity rate in the UK?
As of 2024/2025, the average UK electricity rate under the Ofgem Energy Price Cap is approximately 24.5p per kWh (from October 2024). However, rates vary by supplier, tariff type, and region. We default to 28p/kWh in our calculator to provide a slightly conservative estimate. You should check your latest energy bill or supplier's website for your exact rate and adjust the calculator accordingly.
Which appliances use the most electricity?
The biggest energy consumers in a typical home are: electric showers (7,000–10,500W), electric ovens and hobs (2,000–3,000W), kettles (2,200–3,000W), tumble dryers (2,000–3,000W), and immersion heaters (3,000W). However, always-on appliances like fridge-freezers, though lower wattage (100–200W), accumulate significant costs because they run 24/7 — typically costing £50–£80 per year.
How can I reduce my electricity bill?
Practical steps to reduce your electricity bill include: switching to LED lighting (saves up to £75/year), using a smart thermostat, washing clothes at 30°C instead of 40°C, air-drying clothes instead of using a tumble dryer, switching off devices at the wall rather than leaving on standby, using a slow cooker instead of an oven for suitable meals, and ensuring your home is well-insulated to reduce heating demand.
Is this calculator accurate?
This calculator provides reliable estimates based on the wattage and usage hours you input. Actual costs may vary slightly due to factors like appliance efficiency degradation over time, power fluctuations, variable tariff rates (time-of-use tariffs), and seasonal usage changes. For the most precise measurement, consider using a plug-in energy monitor on individual appliances.