How to Calculate Electricity Costs for Appliances

Trying to cut electrical costs? Want to figure out just how much electricity your dryer uses? With a little math, you can easily find out how much each appliance costs you.

Difficulty:

Moderate

Instructions

Things You'll Need

• calculator
• The model plate on appliance you wish to calculate
• recent electric bill
• Electricity Usage Monitor (optional)

1. 

   To get a general idea of how much electricity your appliance uses, look on the bottom or back of the appliance, on its nameplate. Most appliances will have the maximum wattage stamped on it. If you have wattage, skip to step 3. On some, the electrical usage is marked in Amperes. If you have a number with A after it, continue to step 2.

2. If you want a more accurate measure of how much electricity your appliance is using, you need an electrical usage monitor, like Kill-A-Watt. It will measure the watts used per hour,

3. You need to convert the amps to watts. To do so, take the amperes and multiply by the voltage used by the appliance. Most appliances use 120 volts, but larger appliances such as stoves and dryers use 240 volts.

   Example: 24A x 240V = 5760 Watts

4. Take your wattage and convert it to kilowatts/hour (KWh). Just divide the wattage by 1000, or move the decimal point back three spaces.

   Example: 5760 Watts/1000 = 5.76 KWh

5. Now you need to look at your electric bill and find out what your electric company charges. There will be two type of charges listed: Power Supply and Delivery/Distribution. Add these two rates together.

   Example:
   Power Supply: 274 KWh @ .06486
   Distribution: 274 KWh @ .03547
   .06486 + .03547 = $.10003 per KWh

6. Take your charge per KWh and multiply it by your estimated KWh used. You will then have how much it costs per hour to use that appliance.

   Example: 5.76 KWh x $.10003 = $.576/hour

7. You can then multiply the hourly rate by the number of hours you use that appliance a day to figure out the daily cost; hours a week to figure out the hourly cost; and so on.

8. Some electrical companies charge different rates for different times of the day, which makes the math a bit more complicated. If so, you'll need to estimate the number of hours you use the appliance during each rate.

   Example: Your electric company charges $.10/hr (rate A) during most of the day, but from 7-9 AM and 5-8 PM, the rate increases to $.12/hour (rate B). You have a fridge which uses 725 watts (.725 KW).

   So in 24 hours, your cost would be:
   (KW x A)hours at A + (KW x B)hours at B
   (.725 x $.10)19 + (.725 x $.12)5 = $1.185/day

Tips & Warnings

• You may be able to find your electrical company rates online.

• These numbers will give you a general estimate of how much electricity an appliance uses. To get a more accurate measurement, you'll need an electricity usage monitor, such as Kill-A-Watt.

Resources

• P3 International P4400 Kill A Watt Electricity Usage Monitor
• Typical wattages for various appliances