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Electricity cost calculator

Electricity cost of running an appliance per hour, day, month and year, from its wattage, hours of use and your price per kWh (unit).

更新于 已验证的示例：5

h
days
$
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Cost per month
$
Cost per month: $27.00
小数位数：2；取最近值，等距时取偶数末位
Cost per year
$324.00
Cost per day of use
$0.90
Cost per hour
$0.2250
Energy per day of use
6kWh
Energy per month
180kWh
Energy per year
2,160kWh
The rated power is a maximum: fridges, ACs and heaters cycle on and off, so their real use is usually lower. Tariffs with slabs, fixed charges or time-of-day rates will differ.

Running it 4 h a day uses 6 kWh per day of use — 180 kWh a month, about $27.00 at $0.150 per kWh, or $324.00 a year.

Monthly cost with the same use (4 h a day, 30 days)

LED bulb 9 W$0.16Laptop 60 W$1.08Fridge 150 W$2.70Yours: 1.5 kW$27.00AC 1.8 kW$32.40
计算方法 S

  1. Power in kilowatts

    P=1,500 W×11000=1.5 kWP = \frac{1{,}500\ \mathrm{W}\times 1}{1000} = 1.5\ \mathrm{kW}

  2. Energy per day

    Eday=1.5 kW×4 h=6 kWhE_{\text{day}} = 1.5\ \mathrm{kW}\times 4\ \mathrm{h} = 6\ \mathrm{kWh}

  3. Energy per month and year

    Emonth=6×30=180 kWh,Eyear=12×Emonth=2,160 kWhE_{\text{month}} = 6\times 30 = 180\ \mathrm{kWh},\quad E_{\text{year}} = 12\times E_{\text{month}} = 2{,}160\ \mathrm{kWh}

  4. Cost

    costmonth=180×0.15=27,costyear=324\text{cost}_{\text{month}} = 180\times 0.15 = 27,\quad \text{cost}_{\text{year}} = 324

    Money is shown rounded to the currency's minor unit; the year is 12 months of the pattern you entered.

关于Electricity cost calculator

The calculator turns an appliance's power rating into energy and money. Energy per day is the power in kilowatts times the hours of use, in kilowatt-hours (kWh); the monthly figure multiplies that by the days used, the yearly one by 12 months, and each is priced at your tariff per kWh. A kWh is the "unit" counted on electricity bills.

People use it to compare appliances or to see what a heater or air conditioner adds to a bill. The default, a 1.5 kW heater running 4 hours a day for 30 days at 0.15 per kWh, uses 6 kWh a day and 180 kWh a month: 27.00 a month and 324.00 a year.

The rated wattage is a maximum. Fridges, air conditioners and heaters with thermostats cycle on and off, so their real use is lower, and tiered tariffs, standing charges and time-of-day rates change the final bill.

计算示例

1.5 kW heater, 4 h a day, 30 days at 0.15

Appliance power
1500 W
Hours used per day
4 h
Days used per month
30 days
Price per kWh (unit)
0.15
Energy per day of use
6 kWh
Energy per month
180 kWh
Cost per month
27.00
Cost per year
324.00

核验来源：DOE method: 1500 W × 4 h ÷ 1000 = 6 kWh/day; × 30 × 0.15 = 27.00; × 12 = 324.00

100 W bulb, 5 h a day at 0.12

Appliance power
100 W
Hours used per day
5 h
Days used per month
30 days
Price per kWh (unit)
0.12
Energy per month
15 kWh
Cost per month
1.80

核验来源：Python 3.8 decimal: 0.1 kW × 5 × 30 × 0.12

Two 1 hp motors, 8 h on 22 working days at 0.20

Appliance power
1 hp
Hours used per day
8 h
Days used per month
22 days
Price per kWh (unit)
0.20
Number of appliances
2
Energy per day of use
11.9312 kWh
Cost per month
52.50
Cost per year
629.97

核验来源：Python 3.8 decimal: 2 × 745.69987 W × 8 h = 11.9312 kWh/day; × 22 × 0.20 = 52.4973

Ten 9 W LED bulbs, 6 h a day at ₹8

Appliance power
9 W
Hours used per day
6 h
Days used per month
30 days
Price per kWh (unit)
8
Number of appliances
10
Energy per month
16.2 kWh
Cost per month
129.60

核验来源：Python 3.8 decimal: 10 × 9 W × 6 h × 30 = 16.2 kWh; × 8 = 129.60

常见问题

How do I calculate the cost of running an appliance?

Multiply the power in kilowatts by the hours of use to get kilowatt-hours, then multiply by the price per kWh. A 2,000 W (2 kW) heater used for 3 hours uses 6 kWh; at 0.15 per kWh that costs 0.90. The US Department of Energy gives the same method: watts × hours used per day ÷ 1,000 = daily kWh.

What is a unit of electricity?

One unit is one kilowatt-hour (kWh): 1,000 watts used for one hour, which is 3.6 megajoules of energy. A 100 W bulb takes 10 hours to use one unit and a 2 kW kettle takes 30 minutes. Bills in the UK, India and many other countries count units, and the price per unit is the tariff to enter here.

How do I find an appliance's wattage?

Look for the rating label on the back or base of the appliance, or in its manual; it lists watts or kilowatts. If it gives only amps, multiply by the supply voltage, as the US Department of Energy suggests: 5 A at 230 V is 1,150 W. A plug-in energy meter measures real consumption, including standby power and thermostat cycling.

How much electricity does a fridge use?

Less than its rating suggests, because the compressor switches on and off. The US Department of Energy suggests dividing the hours a fridge is plugged in by three to estimate its full-power running time, so a 150 W fridge runs about 8 hours a day: 1.2 kWh a day, or 36 kWh in a 30-day month. The kWh-per-year figure on its energy label is a better guide when you have it.

“Electricity cost calculator”有多准确？

准确性取决于输入值和方法的假设。十进制运算使用50位有效数字，但估算、数值方法和源数据的精度可能较低；显示时的舍入并不能消除这些限制。 已按独立来源核验的计算示例：5。 例如，“1.5 kW heater, 4 h a day, 30 days at 0.15”根据DOE method: 1500 W × 4 h ÷ 1000 = 6 kWh/day; × 30 × 0.15 = 27.00; × 12 = 324.00进行核验。

这种方法出自哪里？

U.S. Department of Energy — Estimating appliance and home electronic energy use; BIPM SI Brochure (9th ed.), Table 8 — the kilowatt-hour is 3.6 MJ.

关于此计算器

Eday=P×h×n1000 kWh,costmonth=Eday×d×tariff,costyear=12×costmonthE_{\text{day}} = \frac{P \times h \times n}{1000}\ \text{kWh},\quad \text{cost}_{\text{month}} = E_{\text{day}} \times d \times \text{tariff},\quad \text{cost}_{\text{year}} = 12 \times \text{cost}_{\text{month}}

来源

  1. U.S. Department of Energy — Estimating appliance and home electronic energy use
  2. BIPM SI Brochure (9th ed.), Table 8 — the kilowatt-hour is 3.6 MJ

已对照来源验证

此计算器包含 5 个已解示例，答案来自独立来源。这些示例会在测试套件中运行，你也可以在此运行验证。

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