How to use this standby power cost calculator
Add each device that uses electricity while it is not actively in use. Enter the idle or standby watts, how many hours per day the device stays in that state, and how many similar devices you have.
Mark a device as avoidable only if you would realistically turn it off, unplug it, or place it behind a switched outlet. A router, modem, medical device, refrigerator, or clock you rely on should usually stay marked as not avoidable.
If you are comparing standby cost with active device use, the TV Electricity Cost Calculator and Refrigerator Energy Cost Calculator are better for devices with normal operating cycles.
Standby power cost formula
standby kWh per day = standby watts x idle hours per day x quantity / 1000yearly standby cost = standby kWh per day x 365 x electricity price per kWhpotential savings = avoidable standby cost x reduction percentagepayback months = control cost / monthly savingsThe calculator sums every device, then separates total standby cost from potentially avoidable savings. The payback estimate compares possible yearly savings with the cost of a smart plug, smart strip, or switched power strip.
Assumptions and methodology
This is a practical standby power estimate, not a live meter. The most important input is measured standby watts. If you do not know the exact number, use the reference chart as a starting estimate and replace it later with a plug-in meter reading.
The reduction percentage exists because real savings are rarely perfect. A smart plug may draw a small amount of power, some devices may need to stay ready, and some standby modes return after software updates or convenience settings.
DeviceCalc treats routers, modems, refrigerators, medical equipment, clocks, and safety devices carefully. They can be included for cost awareness, but the calculator does not assume they should be turned off.
Example calculations
Living room and office standby load
With the default devices, electricity price of $0.18/kWh, and 80% avoidable reduction, the estimated standby use is 141 kWh per year. That costs about $25.32 per year, with about $16.47 of potential yearly savings from avoidable loads.
Common standby power examples
These are starting estimates for a vampire power calculator, not guaranteed ratings. Actual standby watts vary by model, settings, network state, display brightness, quick-start mode, and connected accessories.
| Device or mode | Starting standby watts | Yearly cost at $0.18/kWh | Planning note |
|---|---|---|---|
| TV standby | 0.3-2 W | $0.47-$3.15 | Small per TV, but common across several screens. |
| Streaming box or DVR | 5-15 W | $7.88-$23.65 | Often a larger idle load because it may stay ready all day. |
| Game console rest mode | 1-10 W | $1.58-$15.77 | Settings such as quick start, downloads, and USB power matter. |
| Printer standby | 1-5 W | $1.58-$7.88 | A candidate for switched outlets if wake-up convenience is acceptable. |
| Microwave or oven clock | 2-5 W | $3.15-$7.88 | Not always practical to switch off, but useful for comparison. |
| Router or modem | 6-20 W | $9.46-$31.54 | Usually an always-on service load, not a standby-saving target. |
What should you turn off first?
Usually worth checking
- Streaming boxes, DVRs, set-top boxes, and quick-start modes.
- Game consoles left in rest mode for downloads or USB power.
- Printers, audio receivers, powered speakers, and old chargers.
- Office setups with several monitors, docks, and accessories.
Usually not the first target
- Routers, modems, ONTs, and mesh nodes you need online.
- Refrigerators, freezers, security devices, and medical equipment.
- Clocks or appliances where losing settings creates daily friction.
- Very low-power devices where a new smart plug would never pay back.
Related calculators
TV Electricity Cost Calculator
Estimate TV electricity use and running cost from watts, hours, electricity price, and standby power.
Refrigerator Energy Cost Calculator
Estimate refrigerator electricity use and annual running cost from kWh, watts, and electricity price.
Freezer Energy Cost Calculator
Estimate chest freezer or upright freezer electricity cost from kWh/year, watts, placement, and electricity price.
Dehumidifier Electricity Cost Calculator
Estimate dehumidifier electricity cost from watts, annual kWh, runtime, efficiency, electricity price, and number of units.
Air Purifier Electricity Cost Calculator
Estimate air purifier electricity cost from watts, daily runtime, annual kWh, electricity price, and number of units.
Router Backup Power Runtime Calculator
Estimate how long a UPS, DC mini UPS, power bank, or power station can keep a router, modem, ONT, or mesh Wi-Fi online.
FAQ
What is standby power?
Standby power is electricity a device uses while it is idle, asleep, waiting for a remote signal, keeping a clock on, maintaining network readiness, or staying in a quick-start mode. It is also often called vampire power or phantom load.
How do I measure standby watts accurately?
Use a plug-in electricity meter when possible. Product labels and specifications can be useful, but they may list maximum power, average power, or test-condition values rather than your exact standby mode.
Is standby power worth worrying about?
One efficient TV may cost very little in standby, but several always-ready boxes, printers, consoles, audio devices, and displays can add up. The calculator helps identify whether the total is small, moderate, or worth changing.
Should I unplug my router or modem to save standby power?
Usually no. A router or modem is normally an always-on service device, not a standby-saving target. Add it if you want to understand cost, but mark it as not avoidable unless you intentionally power it down.
Does a smart plug always save money?
No. A smart plug or smart strip has its own cost and may use a small amount of power. It makes more sense when the controlled devices have a meaningful avoidable standby load or when it improves convenience.
What electricity price should I use?
Use the price per kWh from your electricity bill. If your bill includes time-of-use pricing, taxes, or delivery charges, choose the rate that best reflects the energy you are trying to estimate.
Why is this an estimate instead of an exact bill number?
Real standby power changes by model, firmware, setting, network state, battery charging state, and connected accessories. The formula is transparent, but exact values require measured watts and your local electricity price.