Manu. uses the term "kilowatt per hour" - bogus? Under the section "Product Description - From the Manufacturer", the verbiage (generated by the marketing department probably, not the engineers) says "it will tell you the efficiency of that item by displaying the kilowatt per hour." I am not an engineer and I'm welcoming corrections, but it seems to me that "kilowatt per hour" is a mostly useless measure unless you're talking about the delta (change) in power usage over time. This has nothing to do with "efficiency" and also I'm pretty sure this device does NOT measure it. It measures kilowatt-hours, a useful measure of energy used, which is absolutely not the same thing as "kilowatt per hour."
The gaffe by the marketing people does not detract from the usefulness of the device.
OldAmzonian, perhaps you're the one who's guilty of misinformation. The Kill-A-Watt does indeed calculate power factor. For your information, PF is a trivial calculation for any device that already measures true power, voltage and amps...
Yes, "kilowatt per hour" is incorrect and likely meaningless for this context. Watt is a measure of power--a rate of energy per time, in joules / second. A "watt-hour" would be (an average of) 1 watt of power over 3600 seconds, or 3600 joules--a measure of cumulative energy usage.
See also http://en.wikipedia.org/wiki/Watt#Confusion_of_watts.2C_watt-hours.2C_and_watts_per_hour
Censor, that's an average of 0.064 kW per hour, or 64 watts. That adds up to about 560 kWh per year, which is pretty darn good. According to a spreadsheet on the Energy Star website, the most efficient models have top freezer. The most efficient within that group are estimated to use about 410 to 450 kWh per year (20-21 cf). At roughly $15/year savings (150 kWh x 10 cents), you'd never get a payback, so stick with what you have.
BTW, my relatively new side-by-side model (not the most efficient design) uses 840 kWh/year.
I have a simple webpage calculator for a Kill A Watt on my website. You can input the numbers you get, such as above, and get the results. It's located here: http://www.sustainabilitybythesea.org/calculators/kill-a-watt-calculator/
Putting in your numbers and assuming 13 cents per kWh (your mileage may vary) I get 46 kWh a month (or 552 kWh a year) for a total of $72.66 in costs per year. Pretty similar to what Whetstone got.
I'm surprised this fridge is getting a good reading. It's a top freezer, but I got it in 1994!! I can probably improve it be cleaning the rubber lining on the doors and the grills in the back which haven't been cleaned in years :-)