Enter any appliance's wattage and hours to find its daily, monthly and yearly electricity cost, with a comparison chart and money-saving tips.
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The calculator converts the appliance's wattage to kilowatts by dividing by 1,000, then multiplies by the daily usage hours to get energy in kilowatt-hours (kWh). It multiplies the daily kWh by your electricity rate to get the daily cost, then scales it to monthly (x30) and yearly (x365) totals. Because nameplate wattage is the maximum draw, results are estimates; real bills also include taxes, fixed charges and tiered rates. Everything is explained step by step, and the calculations are transparent so you can check them.
Electricity is billed in kilowatt-hours, usually written kWh. A kilowatt-hour is the energy used by a 1,000 watt appliance running for one full hour, or by a 100 watt appliance running for ten hours. Your appliance label shows watts, which is power (how fast it draws electricity at a given moment). To find the energy it uses, convert watts to kilowatts by dividing by 1,000, then multiply by the number of hours it runs. Multiply that energy by your price per kWh and you have the cost. That three-step chain (watts to kW, kW times hours, kWh times rate) is the entire basis of this calculator.
Start by choosing your currency, then find the wattage on your appliance: it is usually printed on a rating plate, a sticker on the back or base, in the manual, or on the manufacturer website. Next, estimate how many hours per day the appliance actually runs. Note the difference between running time and plugged-in time: a space heater with a thermostat cycles on and off, so its real draw can be 30 to 50 percent below the nameplate rating. Finally, enter your electricity rate per kWh, which you will find on your utility bill under an energy charge or price per kWh line. The calculator immediately shows daily, monthly and yearly energy use and cost, so you can tweak the hours or rate and watch the numbers move.
Take a 100 watt LED-era work lamp used 8 hours a day at a rate of $0.16 per kWh. First convert to kilowatts: 100 / 1,000 = 0.1 kW. Multiply by the hours: 0.1 × 8 = 0.8 kWh per day. Multiply by the rate: 0.8 × $0.16 = $0.128 per day. Over 30 days that is $3.84 per month, and over 365 days it is $46.72 per year. Now compare a 1,500 watt space heater used 6 hours a day at $0.15 per kWh: 1.5 × 6 = 9 kWh per day, costing $1.35 per day, $40.50 per month, and $492.75 per year. The heater costs more than ten times the lamp every month, even though it runs fewer hours, because its wattage is fifteen times higher. For reference, 1500 W is the classic space-heater rating used across energy guides, so this comparison is realistic. Small watts add up slowly; big watts add up fast.
The appliances that move your bill most in a typical home are the ones that heat or cool, and they are also the most common culprits when bills jump unexpectedly. Space heaters (1,000-1,500 W), tumble dryers (2,500-3,000 W), electric showers (7,000-9,000 W) and central air conditioners (3,000-4,000 W) dominate because they draw huge power for hours at a time. Water heaters (3,000-4,500 W) and electric ovens (2,000-5,000 W) sit in the next tier, followed by refrigerators: their wattage is modest (100-200 W) but they run around the clock, which is why they still rank near the top of annual consumption. By contrast, LED bulbs (8-15 W), laptop computers (25-100 W), LED TVs (60-120 W) and phone chargers (5-25 W) cost pennies per day even with generous use. Kettles and hair dryers look scary on the label (1,800-3,000 W) but run for minutes, so their monthly total stays small. The pattern to remember: long hours times high watts is what hurts; one without the other is usually cheap.
A flat rate charges the same price per kWh all day, which is what this calculator assumes by default. Many utilities also offer time-of-use tariffs, sometimes called peak and off-peak rates, where electricity is cheaper late at night and more expensive during evening peaks. On such a plan, shifting washing machines, dryers, dishwashers and EV charging into off-peak hours genuinely lowers the bill, while on a standard single-rate tariff the time of day makes no difference at all. Some regions use tiered or slab tariffs instead, where the price per unit rises as you consume more: in that case the average rate on your bill already reflects your tier, and cutting a few kilowatt-hours can pull you down into a cheaper slab. Check your bill for words like peak, off-peak, tier, slab or time-of-use before choosing a strategy.
Standby power, also called phantom load or vampire draw, is the electricity appliances consume while switched off but still plugged in. TVs, game consoles, set-top boxes, microwaves with clocks and device chargers each draw 0.5 to 15 watts continuously, and across a whole household standby power typically accounts for 5 to 10 percent of the bill. A single 35 watt entertainment setup on standby all day uses 0.84 kWh daily; at $0.16 per kWh that is $0.13 a day, $4.03 a month, nearly $49 a year, for doing absolutely nothing. The fix is simple: smart power strips or switchable plugs with a master switch let you cut whole entertainment and office setups to true zero with one press, and unplugging chargers when the device is full removes their small but constant drain.
Start with the highest-cost appliance this calculator reveals and attack that first, because cutting hours on the biggest load beats trimming a dozen small ones. Set cooling thermostats a couple of degrees higher: each degree of air conditioning change shifts consumption noticeably, and a fan costs far less per hour than a compressor. Replace incandescent bulbs with LEDs, which use roughly 75 percent less energy for the same light, and when big appliances wear out, choose models with strong efficiency ratings (such as ENERGY STAR or a 5-star rated AC) because their purchase price is typically recovered through electricity savings within a few years. Run washing machines and dishwashers on full loads, wash in cold water where possible, and air-seal drafts around doors and windows so your heating and cooling do not fight leaks. These are estimates for planning; your real bill also includes taxes, fixed standing charges and tiered pricing, so use this calculator to compare appliances and habits, not to reproduce the exact bill line.
Convert to kilowatts, multiply by hours, multiply by rate: 100 / 1,000 = 0.1 kW; 0.1 × 8 = 0.8 kWh; 0.8 × your rate per kWh is the daily cost. At $0.16 per kWh that is $0.128 per day, $3.84 per month, and $46.72 per year. That is much cheaper than running high-wattage heating appliances.
Heating and cooling appliances top the list: space heaters, electric showers, tumble dryers, central air conditioners and water heaters. Refrigerators use less power but run 24 hours a day, so they still rank high on annual consumption. Lighting and entertainment, like LED bulbs, laptops and TVs, are small contributors by comparison.
Standby power, also called phantom load or vampire draw, is the small continuous draw of appliances that are switched off but plugged in: TVs, consoles, microwaves with clocks, and chargers. Each draws roughly 0.5 to 15 watts, and together they typically account for 5 to 10 percent of a household bill. A 35 watt setup on standby all day costs about $4 a month at $0.16 per kWh, for nothing.
Watts measure power, how fast a device uses electricity at a given moment, while kilowatt-hours measure energy, the total used over time. 1,000 watts is 1 kilowatt; running 1 kilowatt for one hour is 1 kilowatt-hour (kWh). Your bill charges for energy (kWh), not power (watts), which is why both the wattage and the hours matter.
The wattage is on the appliance's rating plate or label, usually on the back or base, and also in the manual or on the manufacturer website. Your electricity rate per kWh is on your utility bill, listed as an energy charge or price per kWh; on some bills you can compute it as the total amount due divided by the kWh used. Remember that the nameplate wattage is the maximum draw, so cycling appliances like fridges and heaters average well below it.
Target the highest-cost appliance first: reduce its hours or replace it with a more efficient model. Switch to LED bulbs, set cooling thermostats higher, run washers and dishwashers on full loads with cold water, seal air leaks, unplug standby loads with switchable power strips, and if your utility offers cheaper off-peak rates, shift heavy appliances to those hours. The highest-impact savings always come from heating and cooling equipment. To calculate the cost of one appliance at a time, enter its wattage, hours and rate in the fields above.
Only if your utility uses time-of-use pricing, sometimes called peak and off-peak tariffs or plans like Economy 7. On those plans, overnight electricity is cheaper and daytime or evening electricity is more expensive. On a standard flat-rate tariff the price is the same around the clock, so the time of day makes no difference.
Bills include more than the appliance energy this calculator estimates: taxes, fixed standing charges, fuel surcharges, and tiered or slab pricing where the rate rises with usage all sit on top. Duty cycles matter too: a fridge is plugged in 24 hours but its compressor cycles, so it averages far below its label wattage. Use the calculator for comparing appliances and habits; it estimates the energy portion, not the whole bill.