Appliance Cost Calculator Application

Note: appliances with cooling or heating will only be on a percentage of the time, probably 20%-50%. so you can halve the cost or the time.
VA is not Watts(W).

Where PF is power factor. (rms is Root Mean Squared).

When measuring my computer, PF was 0.68. see article on VA vs. Watts.

$\mathrm{V(olts)}\times \mathrm{A(amps)}=\mathrm{W(atts)}$

Using the Kill-A-Watt EZ or PS 10 power WattMeter is a good way to get the real wattage used.

feed it into your calculator one of 2 ways:

$\frac{\$}{\mathrm{month}}=\frac{W\times \mathrm{HoursOn}\times \mathrm{31days}\times \mathrm{\$0.0816perkWH}}{1000}$ $$

or

$\frac{\$}{\mathrm{month}}=\frac{\frac{\mathrm{VA}}{\mathrm{PF}}\times \mathrm{HoursOn}\times \mathrm{31days}\times \mathrm{\$0.0816perkWH}}{1000}=\frac{\frac{\mathrm{VA}}{0.68}\times \mathrm{HoursOn}\times \mathrm{31days}\times \mathrm{\$0.0816perkWH}}{1000}$

or

$\frac{\$}{\mathrm{month}}=\frac{V\times A\times \mathrm{HoursOn}\times \mathrm{31days}\times \mathrm{\$0.0816perkWH}}{1000}$ $$

See Clark PUD article on the equation. It's actually 120V not 115V, because I measured it. that was probably a typo or some accidental misinfo.

most plug-in appliances run on 120V (120VAC). clothes dryers & stoves: check your circuit breaker & multiply by 220V. your clothes washer 15A, dishwasher 20A, microwave 15A-20A, fridge probably run on 15A (check your breaker or back of fridge).

remember, this is worst-case cost.

found the equation on the PUD web site (cool!). hard to find.

There is also the P3 International Kill-A-Watt Power Usage Meter for $21-60. Also at Home Depot and Lowe's.