---
title: "Electricity cost calculator — free, runs in your browser"
description: "What an appliance costs to run, per hour, day, month and year. Free, no sign-up, and nothing you enter leaves your browser."
url: https://atoneplace.net/tools/electricity-bill-calculator/
site: "At One Place"
---

# Electricity cost calculator

What an appliance costs to run, per hour, day, month and year.

## How it works

Takes an appliance wattage, how long it runs, and your tariff, and gives the running cost over several periods.

The arithmetic is straightforward — kilowatt-hours are watts × hours ÷ 1000 — but the wattage is where estimates go wrong. The figure on the label is usually maximum draw, not typical. A fridge rated 150 W does not draw 150 W continuously; its compressor cycles, and actual consumption is often a third of the nameplate figure. Anything thermostatically controlled behaves this way.

Standby power is the one people miss. Individually trivial, collectively it commonly runs to several per cent of a household bill, because it applies every hour of every day rather than the few hours an appliance is in use.

Heating and cooling dominate almost every bill. A 2 kW heater run for four hours uses more than a laptop does in a month.

> This tool runs entirely in your browser. Nothing you enter is sent to a server, logged or stored, and the page keeps working with the network disconnected.

## Common questions

### How do you calculate the running cost of an appliance?

Multiply watts by hours, divide by 1,000 for kilowatt-hours, then multiply by your unit rate.

### Does an appliance draw its rated wattage all the time?

Usually not. The label is typically maximum draw. Anything thermostatically controlled — fridges, freezers, heaters — cycles, and real consumption is often far lower.

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## Sources

- Calculated on this page — At One Place (/about/)