Use the calculator below to estimate electricity usage and cost based on the power requirements and usage of appliances. The amount of time and power that each appliance is used varies significantly between households, so for the best results, adjust the usage for each appliance to most accurately reflect your personal usage.
An electricity calculator converts an appliance's power rating and how long you use it into the two numbers that matter on your bill: kilowatt-hours consumed and dollars spent. Enter the wattage, how often it runs, and your electricity price, and you get the cost per day, week, month, and year - which makes it immediately obvious which devices in your home are worth worrying about and which are rounding errors.
The results are frequently surprising. People tend to fixate on leaving a light on, but a modern LED bulb burning eight hours a day costs only a couple of dollars a year. Meanwhile a central air conditioner, an electric water heater, or an old refrigerator can quietly account for a large share of the bill. This calculator lets you check each appliance individually instead of guessing.
Electricity is billed by the kilowatt-hour (kWh), which is the energy used by a 1,000-watt appliance running for one hour. The calculation is straightforward:
kWh = (power in kilowatts) × (hours of use)
And the cost follows directly:
cost = kWh × price per kWh
A 1,000-watt appliance is 1 kW, so running it for 24 hours uses 24 kWh. At 15 cents per kWh that is $3.60 a day, $25.20 a week, and about $1,315 a year. Scaling to longer periods uses 30.44 days per month and 365.25 days per year - the true averages once you account for months of different lengths and leap years - rather than the rough 30 and 365 that introduce noticeable error over a year.
The "use/run at" percentage is the input most people overlook, and it matters enormously for anything thermostatically controlled. A refrigerator is plugged in 24 hours a day, but its compressor is not running the whole time - it cycles on and off to hold temperature, typically running perhaps 20% of the time. Entering 750 W for 24 hours at 100% would overstate its consumption fivefold.
The same applies to air conditioners, heaters, water heaters, and freezers. Set the hours to the time the appliance is available to run, and use the capacity percentage to reflect how hard it actually works during that window. For appliances that simply run at full power when switched on - a kettle, a toaster, an incandescent bulb - leave the capacity at 100%.
Appliances are rated in different units depending on what they are, so the calculator accepts all the common ones and converts internally:
One important caveat for air conditioners: a BTU or ton rating describes cooling output, not electrical input. A genuinely efficient unit produces more cooling than the electricity it consumes would suggest, so converting the BTU rating directly to kilowatts overstates its electricity use. For an accurate figure, use the unit's rated wattage or divide the BTU rating by its EER (energy efficiency ratio) to get watts drawn.
Real appliances have very different duty patterns, so usage can be entered in whichever unit is natural: minutes or hours per day, hours per week or month, days per week, month, or year, or months per year. A kettle is easiest to think about in minutes per day, a washing machine in hours per week, and a pool pump or space heater in months per year. Everything is normalised internally, so the four output rows are always directly comparable.
The appliance dropdown pre-fills realistic values you can then adjust. As a reference, typical figures are:
Nameplate ratings describe maximum draw, not typical draw. A device labelled 1,500 W rarely averages that, which is exactly what the capacity percentage is for.
Across most homes, consumption concentrates in a handful of categories. Heating and cooling is usually the largest single share, often 40-50% of the annual bill where electric heating or central air is used. Water heating typically follows at 12-18%. Refrigeration accounts for perhaps 4-8%, and because a fridge runs continuously, its efficiency compounds over the year. Lighting has fallen dramatically with the shift to LED - often under 5% now, where it was once 15% or more. Electronics and everything else makes up the remainder.
The practical lesson is that effort should follow the numbers. Adjusting a thermostat by a degree or two usually saves more than switching off a dozen small devices, simply because heating and cooling dominate. Run each of your major appliances through the calculator and the priorities become obvious.
Devices that appear to be off often are not. Televisions, set-top boxes, games consoles, chargers, and anything with a remote or a clock draw standby power - sometimes called vampire or phantom load - continuously. Individually these are small, typically 1-10 watts, but they run 8,766 hours a year and there may be twenty of them in a home. Collectively standby power commonly accounts for 5-10% of residential electricity use.
You can check this with the calculator: enter a small wattage at 100% capacity for 24 hours a day and look at the annual figure. A 5 W device left on permanently uses about 44 kWh a year. Multiply by the number of such devices and the total becomes meaningful. Switchable power strips for entertainment and office clusters are the usual remedy.
The calculator defaults to $0.15 per kWh, close to the US residential average, but real prices vary widely - from around 10 cents in some states to well over 30 cents in others, and higher still in parts of Europe. Your exact rate is on your bill; divide the total charge by the kilowatt-hours consumed to get your true all-in rate, which includes delivery charges and taxes rather than just the energy rate advertised.
Many utilities also use time-of-use pricing, where electricity costs more during peak afternoon and evening hours and considerably less overnight. Where that applies, shifting flexible loads - dishwashers, laundry, EV charging, pool pumps - to off-peak hours can cut costs substantially without reducing consumption at all. Some tariffs additionally use tiered rates, where the price per kWh rises once monthly usage passes a threshold, which makes reducing consumption worth more than the average rate suggests.
Address heating and cooling first. It is the largest load in most homes. Each degree of thermostat setback typically saves 1-3% on heating or cooling energy, and a programmable or smart thermostat captures those savings automatically. Sealing draughts and improving insulation reduce the underlying demand rather than just the settings.
Turn down the water heater. Reducing the setpoint from 60°C to 49°C (140°F to 120°F) cuts standby losses meaningfully and is still comfortably above the temperature needed for household use. Insulating the tank and the first metre of pipe helps further.
Replace remaining incandescent bulbs. An LED uses roughly 85% less electricity for the same light output and lasts far longer. Swapping a 60 W bulb used four hours a day for a 9 W LED saves about 74 kWh a year per bulb.
Run full loads. Dishwashers and washing machines use nearly the same energy regardless of how full they are, so full loads cut the per-item cost. Washing clothes in cold water avoids the water heating that dominates a wash cycle's energy use.
Check the age of your refrigerator. A unit from the 1990s can use two to three times the electricity of a modern equivalent. Because it runs constantly, replacement often pays back faster than for any other appliance.
Air-dry when you can. Clothes dryers are among the most energy-intensive appliances in a home, and line drying costs nothing.
The calculator reports the same appliance over four horizons because each answers a different question. The daily figure is the one to use when comparing appliances against each other, since it strips out how often you happen to use something. The weekly figure suits appliances with a weekly rhythm - laundry, for instance - where a daily average is misleading. The monthly figure is the one that lines up with your bill, making it easy to check whether an estimate is plausible against what you actually pay. The annual figure is the one that changes behaviour, because small numbers become large when multiplied by 8,766 hours.
That last point is worth dwelling on. A device costing three cents a day sounds like nothing, but that is about $11 a year, and a household with ten such devices is spending over $100 annually on things nobody thinks about. Conversely, an appliance that seems expensive to run in the moment - a kettle drawing 1,500 watts - costs very little overall because it only runs for a few minutes. Power tells you how fast energy is used; the annual figure tells you how much it matters. Judging appliances by wattage alone consistently misleads, which is exactly why running each one through the calculator is more reliable than intuition.
To build a picture of an entire household, work through your appliances one at a time and note the annual kilowatt-hours for each. Start with the largest and most continuous loads - heating and cooling, water heating, refrigeration - because they usually account for the bulk of the total. Then add the intermittent high-power items such as ovens, dryers, and dishwashers, and finally the always-on electronics.
Add the annual figures together and compare the total against your actual bills. If your estimate is well below reality, the usual culprits are an underestimated capacity percentage on something thermostatically controlled, or standby loads you have not counted. If it is well above, the capacity percentages are probably too generous. Either way, the reconciliation itself is informative: it tells you where your mental model of your own electricity use is wrong.
A kilowatt-hour is the energy used by a 1,000-watt appliance running for one hour. It is the unit utilities bill by. A 100 W bulb left on for 10 hours uses 1 kWh; a 2,000 W heater uses 1 kWh in half an hour.
Check the nameplate or label, usually on the back or underside, or the manual. If only volts and amps are listed, multiply them: 120 V × 10 A = 1,200 W. For an exact figure on a device that cycles, a plug-in energy monitor measures actual consumption over time.
Because many appliances cycle rather than run continuously. A refrigerator is powered 24 hours a day but its compressor may only run a fifth of that time. Entering 24 hours at 100% would overstate its consumption roughly fivefold. Use hours for availability and capacity for how hard it actually works.
Not for electricity use. BTU/h describes cooling output, not electrical input, and an efficient unit delivers more cooling than it consumes in electricity. Use the rated wattage where available, or divide BTU/h by the unit's EER to get watts drawn. The BTU option here is provided for convenience when that is the only figure you have.
Because months vary in length and leap years add a day every four years. Averaged out, a year is 365.25 days and a month is 365.25 ÷ 12 = 30.44 days. Using 30 and 365 would understate annual consumption by nearly a full day's worth.
Less than most people assume for LEDs, and more than they assume for incandescents. A 10 W LED left on 24 hours a day costs about $13 a year at 15 cents per kWh. A 60 W incandescent in the same situation costs about $79. Enter your own bulb wattage above to see the exact figure.
No - the calculator covers the energy portion only. Most bills also include a fixed monthly service or connection charge that you pay regardless of usage. For a realistic per-kWh rate, divide your total bill by the kilowatt-hours used and enter that figure as the price.
Run each appliance separately and add the annual figures. That approach is more accurate than averaging, because appliances differ so much in both power draw and duty cycle. Comparing the annual totals side by side is also the clearest way to see where your electricity is actually going.
This Electricity Calculator is provided for educational and general informational purposes only and produces estimates rather than exact figures. Actual consumption depends on appliance efficiency, age, condition, ambient conditions, and real usage patterns, and actual bills include fixed charges, taxes, and possibly tiered or time-of-use rates not modelled here. Consult your utility bill and a qualified electrician or energy auditor for decisions with financial or safety implications.