What It CostsRunning Cost Guides
Everything on this site rests on one equation and two numbers you have to find: what the appliance draws, and what you pay for a kilowatt-hour. These eight guides cover where to find both, what to do when the label is missing, and the handful of decisions that change a bill more than any appliance swap ever will.
They cover the formula itself and the mistakes people make with it, a wattage table for the appliances that have no plate left, what standby actually costs across a household, how tariffs work and why a time-of-use rate changes every other calculation on the site, when electricity is genuinely cheapest, why a heat pump beats every electric heater ever made, what home charging costs against a public rapid charger, and how to read your own meter so you can check any of it.
Every figure is either calculated here from the formula or taken from a cited source — the US Department of Energy, ENERGY STAR, the Energy Information Administration or Eurostat. Prices are never presented as facts about your bill: they are examples, and every calculator lets you replace them.
If you want a number rather than the reasoning, start with the electricity cost calculator. The guide most people need first is how to work out a running cost, because it is the one that explains why the answer people get is usually wrong by a factor of three.
Appliance Wattage Table
Typical wattages for fifty household appliances with their usual ranges, plus what to do when the rating plate has worn off or lists volts and amps.
Electricity Tariffs Explained
Unit rate, standing charge, time-of-use and EV tariffs — what each part of a bill means and which number belongs in a running cost calculation.
Heat Pump vs Electric Heater
Why a 100% efficient electric heater is the most expensive way to stay warm, what a COP of 3 actually means on a bill, and where the comparison breaks down.
Home vs Public EV Charging
What home charging costs against a public rapid charger, why the gap is a factor of two to four, and where charging losses fit into the comparison.
How to Read Your Electricity Meter
How to read a digital, dial or smart meter, and how to use it to measure one appliance directly — the check that beats every wattage table.
How to Work Out a Running Cost
The formula, where to find the two numbers it needs, and the four mistakes that make most people's answer wrong by a factor of two or three.
The Biggest Electricity Users in a Home
What actually dominates a household bill, ranked by annual kilowatt-hours — and why the appliances people worry about are near the bottom of the list.
The Cheapest Time to Run Appliances
When electricity is genuinely cheaper, which appliances are worth shifting, and why on a flat tariff the answer is that it makes no difference at all.
What Standby Power Really Costs
Which devices are worth unplugging, which are not, and why a watt left on permanently is worth about a dollar and a half a year — forever.