Standby Power Cost Calculator
Each device starts at the median standby power Berkeley Lab measured for that kind of product. Replace any value with your own reading, set a device to 0 to leave it out, and add other always-on loads in the list.
Total Standby Power
15.37 W
Energy Per Year
134.6 kWh
Cost Per Year
$24.24
Cost Per Month
$2.02
How it works
A device in standby draws a small, steady power around the clock: a set-top box waiting for its schedule, a console listening for updates, a microwave running its clock. Because standby runs all 8,760 hours of the year, each continuous watt adds up to 8.76 kWh a year.
The calculator adds the standby watts of every device you list, multiplies by 8,760 hours and divides by 1,000 to get kWh, then multiplies by your rate. The table shows the same figure for each device so you can see which ones account for most of the total.
The preset values are the medians of Lawrence Berkeley National Laboratory's standby measurements for each product type. Individual models vary widely around the median, so a reading from a plug-in power meter on your own device is more accurate than any preset.
Formula
total W = Σ standby watts of each device kWh per year = total W × 8,760 h ÷ 1,000 (= total W × 8.76) cost per year = kWh per year × rate ÷ 100 cost per month = cost per year ÷ 12
Example
With the six presets (8 + 1.7 + 2.7 + 0.95 + 0.52 + 1.5 = 15.37 W), standby uses 15.37 × 8.76 = 134.6 kWh a year.
At 18 ¢ per kWh that is $24.24 a year, or $2.02 a month. The set-top box alone is 8 × 8.76 = 70.08 kWh, $12.61 a year.
Assumptions and limitations
- Standby power is treated as constant for every hour of the year. Devices that are switched fully off or unplugged part of the time use less; devices that wake for updates or recordings use more.
- The presets are the LBNL medians for each product type (StandbyTable.xlsx, standby.lbl.gov, file dated November 2022); they are typical values, not the reading of any particular model. LBNL notes that most current products draw under 0.5 W and that standby overall accounts for about 5–10 % of residential electricity use.
- The rate is a single flat price per kWh; tiered and time-of-use tariffs, fixed charges and taxes are not modelled. The default 18 ¢ is illustrative.
- A year is 365 days (8,760 hours).
Frequently asked questions
How do I measure a device's standby power?
A plug-in power meter between the outlet and the device shows its draw in watts. Read it after the device has been switched off with its remote or button for a few minutes, since many devices draw more for a short time after switching off.
Why does one watt matter?
One watt running all year is 8.76 kWh. At 18 ¢ per kWh that is about $1.58 a year per watt, so a 20 W always-on load is about $32 a year.
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