Electricity Cost Calculator

Find out how much any appliance costs to run

Electricity bills often feel like mystery charges until you break them down to the individual appliance level. Once you know how many watts an appliance draws and how many hours a day it runs, you can calculate exactly what it costs. This calculator takes those three inputs — wattage, hours per day, and your electricity rate — and instantly shows you the daily, monthly, and annual running cost.

Understanding kilowatt-hours

Electricity is sold in kilowatt-hours (kWh). One kilowatt-hour is the energy used by a 1,000-watt appliance running for one hour, or a 100-watt appliance running for ten hours. Your electricity bill states a price per kWh — this is the rate you pay for each unit of energy consumed.

The formula: energy consumed (kWh) = power (watts) ÷ 1000 × hours of use. Cost = energy (kWh) × rate per kWh. For example, a 2,000-watt electric heater running 4 hours a day uses 8 kWh per day. At a rate of 0.20 per kWh, that costs 1.60 per day, 48 per month, and about 584 per year.

Typical appliance wattages

Knowing typical wattages helps you prioritise where to look for savings:

• LED light bulb: 8–15 W
• CFL light bulb: 15–25 W
• Laptop computer: 30–100 W
• Desktop computer + monitor: 150–350 W
• Refrigerator: 100–400 W (running average, not peak)
• Washing machine: 500–2,000 W
• Dishwasher: 1,200–2,400 W
• Microwave: 600–1,200 W
• Electric oven: 2,000–5,000 W
• Air conditioner (window unit): 500–1,500 W
• Air conditioner (central, per ton): 1,200–2,400 W
• Electric kettle: 1,500–3,000 W
• Hair dryer: 1,000–2,500 W
• Electric vehicle charger (Level 2): 3,300–19,200 W

Where electricity costs most

In most households, the highest electricity consumers are heating and cooling (HVAC), water heating, large kitchen appliances (electric range/oven), and electric dryers. These dwarf the contribution of electronics like televisions, computers, and phone chargers, which are often blamed but are rarely significant in the overall bill.

An air conditioner running 8 hours a day at 1,500 W costs roughly 2.16 per day at 0.18/kWh — about 65 per month. A TV at 100 W for 5 hours costs 0.09 per day — about 2.70 per month. The difference in scale illustrates why replacing a thermostat setting saves more than turning off lights.

Electricity rates worldwide

Electricity rates vary enormously. In the United States, the residential average is around 0.13–0.18 per kWh, but it ranges from under 0.10 in Louisiana to over 0.30 in Hawaii and California. In Germany the rate is among the highest in Europe at around 0.35 per kWh. In many developing countries rates are much lower, partly because electricity is subsidised. Enter the rate from your actual bill for the most accurate result.

How to use the calculator

Enter the appliance's wattage — printed on most devices on a label or in the manual, or found by searching the model number online — along with how many hours a day it typically runs and your electricity rate per kilowatt-hour from a recent bill. The daily, monthly and annual cost appear immediately, updating as you adjust any of the three inputs. Trying a few "what if" scenarios, such as cutting usage hours in half, is a quick way to see exactly how much a change in habit is really worth in money rather than just intuition.

Standby power and phantom loads

Many devices continue drawing a small amount of power even when switched off but still plugged in, a phenomenon often called standby power or a phantom load. Games consoles, set-top boxes, phone chargers and appliances with a remote-control standby mode typically draw a handful of watts around the clock. Individually this seems trivial, but multiplied across dozens of always-plugged-in devices in a household and across 24 hours a day, 365 days a year, phantom loads can add up to a noticeable slice of a bill — often estimated at 5 to 10 percent of total residential electricity use. Running such a device's low standby wattage through this calculator with 24 hours of daily use quickly reveals whether it is worth unplugging.

Comparing appliances before you buy

The same calculator is useful before a purchase, not just after one. Two similar appliances at a shop might list different wattages on their energy labels, and running each candidate's wattage through the calculator at your expected hours of use and local rate turns an abstract spec-sheet number into an actual annual running cost you can compare directly against the price difference between the two models. A slightly more expensive appliance with a much lower running wattage often pays for the difference within a year or two, which is easy to lose sight of when comparing sticker prices alone in a shop.

Private and instant

The calculation runs entirely in your browser, so results update instantly as you adjust any value, and none of the wattage, usage or rate figures you enter are ever sent to a server, logged or shared.