How much it cost to run an iMac 5K for a year?

Discussion in 'iMac' started by seasurfer, Dec 20, 2015.

  1. seasurfer macrumors 6502a

    Dec 12, 2007
    Wonder if anyone know how to calculate how much electricity it costs to run an iMac 5K for a year.

    Let's say you use the iMac 5K for 12 hours a day. What is your electricity bill in a year?
  2. MultiFinder17 macrumors 68000


    Jan 8, 2008
    Tampa, Florida
    You can see Apple's environmental report here. From there, you can calculate how much juice it uses, how much it costs where you life, so how much it will cost you :)
  3. madeirabhoy macrumors 6502a

    Oct 26, 2012
    curious about the answer to this, as not only do i leave my imac on all day, but im thinking about using an old mac mini as a plex server
  4. seasurfer thread starter macrumors 6502a

    Dec 12, 2007
    Yeah, I wonder if someone know how to do the calculations?
  5. Weaselboy Moderator


    Staff Member

    Jan 23, 2005
    Using the power usage numbers from the link MultiFinder17 posted, it uses about 1 watt while sleeping and 60 watts while running. That is while idle, so it would be a little more doing CPU intensive operations.

    So we get this.

    60 watt hours (Wh) X 12 = 720 Wh per day
    1 Wh X 12 = 12 Wh per day

    So 732 Wh per day or .732 kilowatt hours (kWh) per day.

    .732 kWh X 365 = ~267 kWh per year

    267 X cost per kilowatt hour = yearly cost

    Average US cost per kWh is 13 cents. So we get...

    267 kWh X .13 = $34.71 a year
  6. talmy macrumors 601


    Oct 26, 2009
    My Mac mini with 12 TB in 4 external drives uses about 50 watts. Thats 1.2 kWh per day and using Weaselboy's figure of 13¢ per kWh gives $57/year with it on 24/7. Of course most of the power is consumed by those drives.
  7. joema2, Dec 21, 2015
    Last edited: Dec 21, 2015

    joema2 macrumors 65816


    Sep 3, 2013
    This will depend on two things:

    (1) The actual power consumption based on your usage. On my 2015 iMac 27 just sitting there it pulls 95 watts, including the two external RAID arrays. When rendering video in FCPX it pulls about 150 watts but that is brief. It drops to about 80 watts when sleeping but that also includes the RAID arrays. That is based on direct measurements of my iMac.

    The long term average of an iMac 27 with no external drives might be about 90-95 watts, including modest sustained usage. However a USB bus-powered HDD only pulls about 2-3 watts.

    If it sleeps a lot it would be less. In general 95 watts sustained is probably close to the high limit of what the average person would do over time, so I will use that number.

    (2) Your local cost of electricity. The U.S. average is 12 cents per kilowatt hr, but this varies widely by state. In Hawaii it's 35 cents per Kwh, in New York it's 19 cents, in Washington State it is 8.5 cents per Kwh. Details:

    If we use an average iMac power consumption of 95 watts, for 12 hrs this is 95 watts * 12 hr = 1,140 watt hrs.

    Using the US average of 12 cents per Kwh, this would cost 0.12 per Kwh * 1.14 Kwh = about 14 cents per 12-hr usage day.

    A year would be 365 times that, assuming it was used the same amount each day, or 365 * 0.14 = or $51.10.

    If you lived in Hawaii that would cost about 40 cents per day or $146 per year.
    If you lived in New York State that would cost about 21.7 cents per day or $79.20 per year.
    If you lived in Washington State it would cost about 9.7 cents per day or $35.40 per year.
  8. seasurfer thread starter macrumors 6502a

    Dec 12, 2007
    Wow. Thanks for detailed calculation. By the way, where do you get the 95 watts per hour number?

    Seems that the iPad Pro consume significantly less power than the iMac 5K.
  9. joema2 macrumors 65816


    Sep 3, 2013
    That is the readout on my UPS that runs my iMac. It shows moment to moment the number of watts. BTW it's 95 watts, not watts per hour. Watts are like horsepower, a measurement of instantaneous power. You wouldn't say horsepower per hour. If you use 95 watts for 1 hr that is 95 watt-hours, but it's not watts per hour.

    Using the IN keyword, Google will convert all these if the units are equivalent. It is easier than looking up a conversion table. E.g.

    95 watts IN horsepower (returns 0.127 horsepower)
    95 watt-hours IN joules (returns 342,000 joules)
    95 watt-hours IN btu (returns 324.153 BTU)
    426 cubic inches IN cubic centimeters (returns 6.98 liters)
    10 acres IN square meters (returns 40468.6 square meters)
    100 pounds force IN newtons (returns 444.822 newtons)
    10 cubic parsecs IN cubic furlongs (returns 3.6E43 cubic furlongs)
    1000 british pounds IN USD (returns 1486.97 dollars)
  10. seasurfer thread starter macrumors 6502a

    Dec 12, 2007

    Thank you for correcting me. What is a UPS?
  11. joema2 macrumors 65816


    Sep 3, 2013

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