⚡ Electricity Cost Calculator

How to Calculate the Running Cost of Any Appliance

The formula is: Daily Cost = (Wattage ÷ 1,000) × Hours Used × Electricity Rate. Wattage divided by 1,000 gives kilowatts (kW). Kilowatts multiplied by hours gives kilowatt-hours (kWh), which is the unit electricity is billed in. Multiply kWh by your tariff rate and you have the cost in your currency. This calculator automates all of that.

Electricity tariffs vary by municipality and are updated regularly. Electricity tariffs vary by region and provider — check your latest bill for your exact rate per kWh.50–$3.00 per kWh, but Johannesburg (City Power), Cape Town (CoCT), and eThekwini have their own tariff schedules that may differ. Check your latest electricity statement or your municipality's website for your exact rate. The rate on your bill is the one to use.

The biggest energy consumers in a typical household are: electric water heater (geyser) — typically 2,000–4,000W, running 6–8 hours per day; electric stove — 2,000–3,500W during cooking; air conditioner — 1,000–3,500W depending on capacity; electric space heater — 1,500–2,500W. These four account for the majority of residential electricity spend. Switching a 3,000W geyser to a solar geyser or heat pump can reduce household electricity bills by 30–40% on its own.

Vampire power — the electricity consumed by devices on standby — is small individually but adds up. A TV on standby uses 1–5W continuously. A microwave clock uses 3–4W. A cable TV box can use 10–20W in standby mode around the clock. Over a year, a home with 10 standby devices averaging 5W each consumes approximately 438 kWh — at $2.50/kWh, that's over $1,000 per year doing nothing useful.

This calculator also helps you evaluate whether a more energy-efficient appliance would pay for itself. If upgrading from a 500W to a 300W PC monitor saves you 200W, and you use it 8 hours per day, that's 1.6 kWh per day, or approximately 584 kWh per year — worth around $1,460 annually at current rates.