Electrical Device Power Calculator

The calculator sums the power draw of multiple household devices, computes daily and monthly energy consumption, estimates electricity costs and determines the required fuse rating for the electrical installation. Enter the rated power, quantity and daily operating hours for each device.

Total power is the sum of all simultaneously running devices: P_total = P1 × n1 + P2 × n2 + … Example: 5 bulbs at 60 W = 300 W, plus a 300 W computer gives 600 W total. The calculator performs these additions automatically.

Fuse rating is based on current draw: I = P / U. For a 230 V supply and 3000 W load: I = 3000 / 230 ≈ 13 A. Select the next standard size above — in this case 16 A. Standard fuse ratings are: 6, 10, 13, 16, 20, 25, 32, 40, 50, 63 A.

Monthly cost = P [kW] × hours/day × 30 days × price [per kWh]. Example: a 200 W refrigerator running 24 h for 30 days: 0.2 kW × 24 h × 30 = 144 kWh × price per kWh.

Approximate power ratings: refrigerator 100–300 W, washing machine 800–2500 W, dishwasher 1200–2400 W, LED television 50–200 W, desktop computer 200–600 W, electric kettle 1500–3000 W, electric iron 1000–2400 W, microwave 700–1200 W, LED bulb 5–15 W, air conditioner 900–3500 W.

A kilowatt-hour (kWh) is the unit of electrical energy used on electricity bills. 1 kWh = 1000 W × 1 h. To calculate consumption: energy [kWh] = power [W] / 1000 × operating time [h]. Example: a 2000 W appliance running for 3 hours consumes 6 kWh.

A typical apartment uses 16 A or 20 A circuit breakers per circuit. A 16 A circuit handles up to 3680 W (16 A × 230 V). Separate higher-rated breakers (20–25 A) are used for electric cookers, water heaters and tumble dryers. The fuse sizing calculator helps you work out the required rating.

The most effective measures are: switching to LED bulbs (up to 80% savings), eliminating standby power (can cost £50–100/year), replacing old appliances with A-rated energy-efficient models, running the washing machine and dishwasher off-peak and improving the building's thermal insulation.

A fuse protects the installation against instantaneous overload — what matters is peak power (W), not energy over time (kWh). Electricity cost, on the other hand, depends on total energy consumed, which is the product of power and operating time. That is why fuse sizing only requires total power, while cost calculation also needs daily hours.

Select a mode: 'Device power sum' lets you enter up to 8 devices (power in W, quantity, daily operating hours), the electricity price and mains voltage (default 230 V). The calculator returns total power, energy consumption, monthly cost and recommended fuse. 'Fuse sizing' mode only requires total load power.