- May 6, 2011
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This is actually a very easy formula. Lets say you overclock your cpu and now you are pulling 20 more watts from the wall. You want an easy ballpark estimate how much more this will cost. The simple formula is:
power_saved / 420 = money saved per day
20 / 420 = about 5 cents per day. Now if your computer is only awake and running 6 hours a day then you have to multiply that result by 6/24. Which is about a penny a day.
Where does the constant 420 come from? The 420 is based on electricity costing 9.92 cents per kwhr :whiste:. That cost is variable pr in the expression pr * hrs * power_saved * 1kw / 1000w. So if you take 0.0992 * 24 * ps * 1 / 1000 you get ps*0.002381. Or ps * 1/420 or ps / 420.
Really all you have to remember is the 420. Take any power savings and divide that by 420 and you get how much money you save per day. Then you can multiply that result by 365 to see how much money you save per year. That leads me to the other easy way to estimate ballpark savings: just take the power saved and turn that into dollars and you get the approximate amount of money saved per year. So if you reduce your power usage by 50 watts, you are going to save roughly 50 bucks a year. (Within +/- 20%) Doesnt get much simpler than that.
Another thing to keep in mind is that 4.2 / 420 = 0.01. So every 4 watts you save is a penny a day. If you dont have a calculator this may be the best way to quickly price your changes in power consumption.
power_saved / 420 = money saved per day
20 / 420 = about 5 cents per day. Now if your computer is only awake and running 6 hours a day then you have to multiply that result by 6/24. Which is about a penny a day.
Where does the constant 420 come from? The 420 is based on electricity costing 9.92 cents per kwhr :whiste:. That cost is variable pr in the expression pr * hrs * power_saved * 1kw / 1000w. So if you take 0.0992 * 24 * ps * 1 / 1000 you get ps*0.002381. Or ps * 1/420 or ps / 420.
Really all you have to remember is the 420. Take any power savings and divide that by 420 and you get how much money you save per day. Then you can multiply that result by 365 to see how much money you save per year. That leads me to the other easy way to estimate ballpark savings: just take the power saved and turn that into dollars and you get the approximate amount of money saved per year. So if you reduce your power usage by 50 watts, you are going to save roughly 50 bucks a year. (Within +/- 20%) Doesnt get much simpler than that.
Another thing to keep in mind is that 4.2 / 420 = 0.01. So every 4 watts you save is a penny a day. If you dont have a calculator this may be the best way to quickly price your changes in power consumption.
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