Energy Consumption Calculator with 67 appliance wattages taken from DOE and utility charts. Watts and daily hours become kWh for a day, month and year, priced at your rate per kWh.
Picking an appliance fills in typical watts and daily use. Type your own nameplate figures if you have them.
Usage Details
Running share is for appliances that cycle on and off. Leave it at 100% when the hours are running hours.
Energy and Cost by Hours per Day
| Used per Day | Energy per Month | Cost per Month |
|---|---|---|
| 30 min | 4.050 kWh | $0.73 |
| 1 h | 8.100 kWh | $1.46 |
| 2 h | 16.20 kWh | $2.92 |
| 4 h | 32.40 kWh | $5.83 |
| 6 h | 48.60 kWh | $8.75 |
| 8 h | 64.80 kWh | $11.66 |
| 12 h | 97.20 kWh | $17.50 |
| 16 h | 129.6 kWh | $23.33 |
| 24 h | 194.4 kWh | $34.99 |
Step-by-Step Working
- Load: 270 W.
- Running time: 4 h a day.
- Daily energy: 270.0 W × 4.000 h = 1.080 kWh.
- Monthly energy: 1.080 kWh × 30 days = 32.40 kWh.
- Yearly energy: 1.080 kWh × 365 days = 394.2 kWh.
- Monthly cost: 32.40 kWh × 18¢ per kWh = $5.83.
Energy Consumption Calculator: Watts to kWh
Energy consumption is power multiplied by time. The Energy Consumption Calculator takes the watts of an appliance and the hours it runs each day, then reports kilowatt-hours, the unit a meter counts and a bill charges for. The U.S. Department of Energy publishes the same method for estimating appliance use.
The Energy Consumption Calculator loads with a desktop computer and monitor at 270 W for 4 hours a day. That is 270 × 4 ÷ 1,000 = 1.080 kWh a day, 32.40 kWh over a 30-day month and 394.2 kWh over a 365-day year. The Department of Energy's own example for a computer and monitor lands on the same 394 kWh.
The large result is the monthly figure, so the tool works first as a monthly energy consumption calculator. A month is always counted as 30 days and a year as 365, which keeps one appliance comparable with the next.
How do I calculate my energy consumption?
Find the watts on the appliance nameplate, multiply by the hours you use it each day, and divide by 1,000. Multiply that daily figure by 30 for a month. A 1,500 W space heater used 2 hours a day comes to 3.000 kWh a day and 90.00 kWh a month.
When the nameplate shows only volts and amps, multiply them to get watts first. The Electrical Power Calculator does that step for DC, single-phase and three-phase loads, and its answer goes straight into the Power field here.
How to calculate energy consumption formula?
The energy consumption formula in the tool carries three more terms than the basic one. Number of Appliances multiplies the watts. Days Used per Week scales the month and the year. Share of Time Running trims the hours for a load that cycles on and off.
Here n is the number of appliances, s is the running share as a decimal and d is the days used per week. A 1,500 W heater used 2 hours a day on 5 days a week comes to 64.29 kWh a month instead of 90.00 kWh. Two of them on all 7 days come to 180.0 kWh.
The same math works as an energy consumption calculator in Excel. With watts in A2, hours per day in B2 and the rate per kWh in C2, the formula =A2*B2/1000*30 gives the monthly kWh. Multiplying that cell by C2 gives the monthly cost.
Where the 67 Appliance Wattages Come From
Many appliance lists give a wattage with no source behind it. Every figure in the Appliance menu of the Energy Consumption Calculator comes from one of three published lists, and the note under the results says which one applies.
The computer figures are from the Department of Energy list reproduced by Virginia Cooperative Extension. It puts a desktop at 120 W awake, a monitor at 150 W awake and a laptop at 50 W. Asleep, the desktop and the monitor each drop to 30 W or less. The default setting is in effect an energy consumption calculator for a PC.
Central air conditioner and refrigerator figures are from the appliance chart of City Water, Light and Power, the municipal utility in Springfield, Illinois. It lists 0.85 kWh per hour per ton for a 14 SEER central unit and 1.2 for a 10 SEER unit. It also lists 82 kWh a month for a refrigerator made in 2002 or later and 168 kWh for an older frost-free model.
The other appliances use the average watts and daily hours in the usage chart from Jackson Energy Cooperative in Kentucky. The window air conditioner presets run from 750 W for 6,000 BTU to 2,395 W for 18,000 BTU, each at 8 hours a day. The table shows what some of the presets return at the default 18 cents per kWh.
| Appliance preset | Watts | Daily use | kWh per month | Cost per month |
|---|---|---|---|---|
| Water Heater, 4 People | 4,500 | 4 hours | 540.0 | $97.20 |
| Window AC, 12,000 BTU | 1,600 | 8 hours | 384.0 | $69.12 |
| AC 1.5 ton, 14 SEER | 1,275 | 8 hours | 306.0 | $55.08 |
| Dehumidifier | 300 | 24 hours | 216.0 | $38.88 |
| Freezer, 15 cu ft | 350 | 14 hours | 147.0 | $26.46 |
| Portable Space Heater | 1,500 | 2 hours | 90.00 | $16.20 |
| Fridge, 2002 or Newer | 114 | 24 hours | 82.08 | $14.77 |
| Clothes Dryer, Electric | 4,350 | 30 minutes | 65.25 | $11.75 |
| Dishwasher | 1,190 | 1 hour | 35.70 | $6.43 |
| Desktop PC and Monitor | 270 | 4 hours | 32.40 | $5.83 |
| TV, 55 inch | 220 | 4 hours | 26.40 | $4.75 |
| Ceiling Fan, High | 100 | 6 hours | 18.00 | $3.24 |
| Washer, Cold Water | 500 | 15 minutes | 3.750 | $0.67 |
A refrigerator is entered differently from everything else. The utility chart gives it as kWh per month, so the tool spreads 82 kWh across the month as 114 W around the clock and the hours stay at 24. Freezers and the dorm refrigerator use running hours instead, 14 a day for a 15 cubic foot freezer.
For a cycling appliance with no preset, enter the plugged-in hours and lower Share of Time Running. Virginia Cooperative Extension suggests dividing a refrigerator's plugged-in time by three, which is a share of about 33 percent.
As an energy consumption calculator for home use, the tool handles one appliance at a time. Run each appliance, note its kWh per month, and add the figures together. Used that way it becomes a household electricity consumption calculator that shows how much of the bill those loads explain.
Cost per Month, Running Hour and 24 Hours
The Electricity Rate field takes cents per kWh and starts at 18. With a rate entered, the Energy Consumption Calculator is also an electricity cost calculator that prices each kWh. The default computer costs $5.83 a month, $0.19 a day and $70.96 a year.
That cost is only the share one appliance adds. A real bill also carries fixed charges and taxes, so the total on paper will be higher than the sum of the appliances you run through the tool.
The third card prices one running hour. For the computer that is 4.86 cents, and for a 1,500 W heater it is $0.27. The same card shows Running Time for 1 kWh, which makes it a 1 unit kWh calculator. The computer takes 3.704 hours to use one unit and the heater takes 40 minutes.
The fourth card answers what happens if the appliance never switches off. The computer left on for 24 hours would use 6.480 kWh a day and 194.4 kWh a month, at a cost of $34.99 a month. When the entry is already 24 hours, the card compares against 12 hours instead.
The Energy and Cost by Hours per Day table lists run times from 30 minutes to 24 hours with the monthly kWh and cost for each. Your own entry is highlighted, so the price of one more or one less hour a day can be read from the rows beside it.
Costs print with a dollar sign, but the math is a plain division by 100. To use it as an energy consumption calculator in India, type the tariff in paise, so ₹8 per unit goes in as 800, and read the dollar figures as rupees. A 1.5 ton air conditioner at 8 hours a day then shows 2,448.00 a month.
Energy Consumption Calculator in Units and kWh
How much kWh is in 1 unit?
There is exactly 1 kWh in 1 unit of electricity. Unit is the word printed on bills in India, while U.S. bills print kWh. 1 unit is equal to 1,000 W running for one hour, 100 W running for 10 hours, or 40 W running for 25 hours.
Is 1000 watt equal to 1 unit?
1,000 watts becomes 1 unit only after it has run for one hour. Watts measure how fast energy is used, and units measure how much has been used. 1 kW is 1,000 watts, so a 1 kW load uses 1 unit per hour and 24 units if it runs all day.
Is 1 kWh equal to 1 hour?
1 kWh equals 1 hour only for a load of exactly 1,000 W. A 3,000 W load uses 1 kWh in 20 minutes. The 270 W computer preset takes 3.704 hours, and a 60 W bulb takes 16.67 hours. The Running Time for 1 kWh row gives this figure for whatever wattage is entered.
What is 40 watts in units?
40 watts is 0.04 units for every hour it runs, so one unit lasts 25 hours. Choose Custom Wattage in the Energy Consumption Calculator, enter 40 W for 24 hours, and it shows 960.0 Wh a day and 28.80 kWh a month. As for how much 40 watts is per hour in money, it is 0.72 cents at 18 cents per kWh.
How much unit does 3000 watts consume in 1 hour?
3,000 watts consumes 3 units in 1 hour. At 18 cents per kWh that hour costs 54 cents, and one unit is gone every 20 minutes. Run 1 hour a day for a month, a 3,000 W load adds 90.00 kWh and $16.20 to the bill.
What is 200 units of electricity?
200 units of electricity is 200 kWh. The 1.5 ton, 14 SEER air conditioner preset uses 10.20 kWh in an 8-hour day, so it goes through 200 units in about 20 days. The computer preset at 32.40 kWh a month would take a little over six months to use the same amount.
How much bill for 500 units of electricity?
The bill for 500 units is 500 times your rate, plus the fixed charges. At 18 cents per kWh the energy part is $90. At a flat ₹8 per unit it is ₹4,000, though Indian slab tariffs charge the later units at a higher rate than the first ones.
What is 300 units free electricity in India?
It refers to PM Surya Ghar: Muft Bijli Yojana, the rooftop solar scheme announced by the Prime Minister's office on February 13, 2024. It aims to give up to 300 units of free electricity every month to 1 crore households that install rooftop solar. 300 units a month is 10 kWh a day, close to what the 1.5 ton air conditioner preset uses in 8 hours.
Air Conditioner Energy Use and Cost
How many kW does a 1.5 ton AC use?
A 1.5 ton AC uses about 1.275 kW at 14 SEER and 1.8 kW at 10 SEER while the compressor runs. As for how many kW 1 ton of AC is, the same utility figures give 0.85 kW at 14 SEER and 1.2 kW at 10 SEER. The table shows three sizes at 8 hours a day and 18 cents per kWh.
| Size | 14 SEER watts | 14 SEER per month | 10 SEER watts | 10 SEER per month |
|---|---|---|---|---|
| 1.5 ton | 1,275 | 306.0 kWh, $55.08 | 1,800 | 432.0 kWh, $77.76 |
| 2 ton | 1,700 | 408.0 kWh, $73.44 | 2,400 | 576.0 kWh, $103.68 |
| 3 ton | 2,550 | 612.0 kWh, $110.16 | 3,600 | 864.0 kWh, $155.52 |
How much bill for 1 hour AC?
One hour of a 1.5 ton AC costs $0.23 at 14 SEER and $0.32 at 10 SEER, at 18 cents per kWh. A 1 ton unit costs $0.15 and $0.22 for the same hour. The per Running Hour card in the Energy Consumption Calculator shows this figure for whichever size is picked.
How much does 30 minutes of AC cost?
30 minutes of a 1.5 ton, 14 SEER AC uses 637.5 Wh and costs about 11 cents at 18 cents per kWh. Switch the Used per Day unit to minutes and enter 30 to see it. The same half hour on a 10 SEER unit uses 900 Wh and costs about 16 cents.
Can I use AC for 12 hours?
An AC can run for 12 hours, and the question is what it adds to the bill. The 1.5 ton, 14 SEER preset at 12 hours uses 15.30 kWh a day and 459.0 kWh a month, which is $82.62. If the compressor runs only 60 percent of that time, set Share of Time Running to 60 and the month drops to 275.4 kWh and $49.57.
Is it expensive to run AC all day?
Running the same AC for all 24 hours uses 30.60 kWh a day and 918.0 kWh a month, which is $165.24 at 18 cents per kWh. That is three times the 8-hour figure of $55.08. The if Run 24 h card shows this comparison for every appliance without changing your entry.
How much is a 5 star AC bill per hour?
A star label prints the yearly kWh for the unit, and India's rating method assumes 1,600 running hours a year. Divide the label figure by 1,600 to get kWh per hour. A label that reads 800 kWh a year means 0.5 kWh per hour, which is 9 cents at 18 cents per kWh or ₹4 at ₹8 per unit.
What is the 3 minute rule for AC?
The 3 minute rule says to wait at least three minutes after an AC shuts off before switching it back on. TCL's support note warns that an earlier restart can cause liquid hammer in the compressor and shorten its life. The rule protects the compressor and does not change the kWh figures above.
Washing Machine Electricity Use
The Appliance menu of the Energy Consumption Calculator has two washer entries from the cooperative chart. Washer, Cold Water is 500 W for 15 minutes a day, and Washer, Hot Water is 600 W for 30 minutes. The Department of Energy list gives a clothes washer nameplate range of 350 to 500 W.
How much electricity does a 7kg washing machine use per hour?
At 350 to 500 W, a washing machine motor uses 0.35 to 0.5 kWh per hour of running, which is 6.3 to 9 cents at 18 cents per kWh. For a 7 kg front loader, LG's label figure for its FHB1207Z2W is 0.06 kWh per kg per cycle, or 0.42 kWh for a full 7 kg load.
How much electricity does a 30 minute washing machine use?
A 30 minute wash at 500 W uses 250 Wh, a quarter of a unit, and costs 4.5 cents at 18 cents per kWh. Enter 500 W and 30 minutes in the Energy Consumption Calculator to see it. Done once a day, that cycle adds 7.500 kWh and $1.35 to a month.
How much electricity does a washing machine use in 24 hours?
A washing machine only draws power during its cycles, so a day's use is one or two loads. The cold water preset comes to 125.0 Wh a day and 3.750 kWh a month. The hot water preset comes to 300.0 Wh a day and 9.000 kWh a month. A 500 W machine that somehow ran for all 24 hours would use 12.00 kWh.
How many watts is a 6kg washing machine?
The kilogram rating is the dry laundry a drum holds, and it does not fix the watts. A 6 kg, 7 kg, 8 kg, 9 kg or 12 kg machine has its wattage printed on the rating plate at the back, and that plate figure is what goes in the Power field. A machine that heats its own water draws far more while the heater is on.
What is the power consumption of an LG 6.5 kg washing machine?
LG lists energy per wash, not watts. Its specification for the 6.5 kg WTG6530W top loader gives 100 kWh per 365 cold washes and 446 kWh per 365 warm washes. That is 0.27 kWh for a cold wash and 1.22 kWh for a warm one.
Warm water makes that load cost 4.5 times as much as cold water. The gap is wider than the 2 times difference in capacity between a 6 kg and a 12 kg drum, so the temperature setting matters more to the bill than the size of the machine.
How much water does a 7kg washing machine use per load?
LG's label figure for its 7 kg FHB1207Z2W front loader is 8.6 litres per kg per cycle, which is about 60 litres for a full load. Its 6.5 kg WTG6530W top loader is listed at 66 litres per wash. Other makes differ, and the water figure is printed on the energy label.
What are the differences between a 6kg and a 7kg washing machine?
A 7 kg machine holds 1 kg more dry laundry per load than a 6 kg machine. On per-kg label figures like LG's, that extra kilogram adds about 0.06 kWh and 8.6 litres to a full load. Washing the same laundry in fewer loads is where the larger drum saves energy.
Laundry and air conditioning are also common loads on backup power. Once the daily kWh from the Energy Consumption Calculator is known, the Battery Size Calculator works back to the capacity needed, and the Battery Life Calculator gives the hours an existing pack will last. The Electrical Energy Calculator covers loads known by volts, amps or ohms instead of watts.