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What Your Always-On Gadgets Actually Cost Per Year

One number does almost all the work here: at the US average residential electricity rate,
every watt drawn continuously for a year costs about $1.62. That is the whole calculation.
A device pulling 2 watts around the clock costs roughly $3.24 a year. One pulling half a watt costs
about 81 cents.

Once you have that figure, most advice about unplugging things collapses under it — and the
few things that genuinely move your bill become obvious. The rate used throughout this page is
18.44¢/kWh, the US average residential price reported by the EIA as of May 2026.
Substitute your own rate from your utility bill if it differs; the method does not change.

The only calculation you need

Annual cost = watts × 8.76 × your rate per kWh. The 8.76 comes from
8,760 hours in a year divided by 1,000 watts per kilowatt. At 18.44¢ that collapses to a single
shortcut worth memorising: $1.62 per watt, per year, running 24/7.

For anything that does not run continuously, add the duty cycle:
watts × hours per day × days per year ÷ 1,000 × rate. Nearly
every mistake people make about home energy comes from ignoring that second formula and reacting to
the wattage number on the label instead.

What always-on devices actually cost

Standby draws for household electronics cluster between about 0.5 and 5 watts, which puts
almost all of them under $10 a year each. The figures below are typical published standby
ranges, converted at 18.44¢/kWh running continuously.

Device Typical standby draw Cost per year, 24/7
Phone charger, nothing plugged in 0.1–0.5W $0.16–0.81
Monitor in sleep 0.5–2W $0.81–3.23
Desk speakers, powered on idle 1–3W $1.62–4.85
Powered USB hub 1–5W $1.62–8.08
Smart plug or smart bulb, idle 1–2W $1.62–3.23
Wi-Fi router or mesh node 5–12W $8.08–19.39
Laptop in sleep ~7W ~$11.31
Desktop PC in sleep ~9.5W ~$15.35

Add up an entire home-office desk — monitor, speakers, hub, charger, laptop asleep —
and you land near 10–15 watts, or roughly $16 to $24 a year for leaving the
whole setup plugged in permanently. That is the real size of the prize, and it is worth knowing
before you spend a Saturday rewiring anything.

Why unplugging your chargers is a waste of your time

A modern phone charger with no phone attached draws somewhere around 0.1–0.5 watts,
which is 16 to 81 cents a year. Unplugging it nightly saves less than a dollar annually and
costs you the wear on the socket and the risk of forgetting.

The “vampire power” advice that circulates every winter is a genuine phenomenon at national scale
— standby accounts for something on the order of 100 billion kWh and $10 billion a year across
the entire United States — but that figure is spread across roughly 130 million households and
every appliance in them. Your share of it is the table above, not a meaningful fraction of your bill.

The exception worth acting on is anything with a display, a motor or a network radio that
you never use. An old cable box, a second router still powered in a cupboard, a printer that stays
warm: these sit at 5–20 watts rather than fractions of a watt, and switching them off is real
money. Sorting by wattage beats sorting by guilt.

The smart plug paradox

A smart plug draws about 1–2 watts itself, which is $1.62 to $3.24 a year. Put one on
a device that idles below that, and the plug consumes more electricity than the thing it is
monitoring wastes. This is the single most counter-intuitive fact in home energy and it is
almost never stated.

Run it against the table. A phone charger idling at 0.3W costs 48 cents a year. Metering it with a
plug that draws 1.5W adds $2.43 a year. You have made the problem five times worse and bought
hardware to do it. The same logic rules out smart plugs on LED lamps, clocks, and most single-charger
setups.

Where smart plugs genuinely pay is the opposite end: one plug controlling a power strip
that feeds an entire desk or entertainment cluster, so a single 1.5W device switches off 15 watts of
downstream load. That flips the maths from a net loss to roughly a 10-to-1 return. The
smart plug
guide works through the payback period on that arrangement in detail, including which picks report
their own consumption honestly.

Why your energy meter is worst exactly where you need it

A plug-in energy meter is the honest way to settle any of this for your own devices —
but nearly every consumer meter is least accurate below about 5 watts, which is precisely the range
standby power lives in. This is a measurement trap, not a product defect, and it explains a
lot of contradictory numbers online.

The cause is power factor. Every phone charger, laptop brick and TV standby circuit uses a
switching-mode power supply, which does not draw current smoothly across the AC waveform — it
pulls it in short spikes. Inexpensive meters that assume a clean sinewave can be substantially off on
that kind of load, and the error is proportionally largest when the load is smallest. A meter that is
accurate within a couple of percent on a 1,000W kettle can be wrong by a wide margin on a 0.5W
charger.

Two workarounds get you a usable answer without better hardware. Measure a whole power
strip at once rather than one device — five items totalling 12 watts sits inside the
meter’s accurate range, and you can divide or subtract from there. And read the accumulated
kWh counter after several days rather than the instantaneous watts display, because
accumulated energy averages out sampling error that a live reading shows raw.

One tell worth knowing: if a meter reads exactly 0.0W on a power brick that is warm to the touch,
the meter is below its detection threshold, not the device. Warmth is dissipated power. A
brick you can feel is drawing something, and the honest reading is “less than this meter resolves”
rather than zero.

What actually moves your bill: heat

Anything that converts electricity into heat dwarfs everything else in your home combined.
A 1,500W space heater run 6 hours a day through a 4-month winter costs about $199 — roughly
twelve times what every gadget on your desk costs running 24/7 for a full year.

The pattern holds across the category. Heat is expensive; electronics are not.

Device Draw Realistic use Cost per year
Space heater 1,500W 6 h/day × 120 days ~$199
Desktop PC in use 200W 8 h/day × 250 days ~$74
Hair dryer 1,800W 10 min/day, all year ~$20
Air fryer 1,500W 20 min, 4×/week ~$19
27″ monitor in use 30W 8 h/day × 250 days ~$11
Entire desk on standby ~12W 24/7, all year ~$19

Read the hair dryer row carefully, because it is the clearest illustration of duty cycle. It draws
more watts than the space heater, and costs a tenth as much, purely because it runs for ten
minutes instead of six hours. Wattage on the label tells you almost nothing on its own.

The practical conclusion: if you want a lower electricity bill, look at heating, cooling, laundry
and hot water before you look at anything with a screen. Optimising your desk is a rounding error on
one winter’s space heating.

The safety number nobody mentions

A standard 15-amp household circuit at 120V carries 1,800 watts, but the National
Electrical Code limits a continuous load — anything running three hours or more —
to 80% of that, which is 1,440 watts. A 1,500W space heater exceeds it on its own, before
anything else on the circuit.

This matters more than the pennies. Most home-office circuits also carry lighting and several
outlets, so a heater plus a desktop plus a monitor can sit well over the continuous limit for an
entire working day. A 20-amp circuit gives you 2,400W total and a 1,920W continuous ceiling, which
accommodates a heater with room to spare.

It also constrains hardware choice: most smart plugs and power strips are rated at 10 or 15 amps
resistive, and a 1,500W heater is at or beyond what many of them are certified to switch repeatedly.
Manufacturers of smart plugs routinely tell you not to use them with space heaters, and that
instruction is about the relay contacts welding, not about the energy.

How this page was compiled

Costs are calculated from published device wattage ranges and the EIA US average residential
electricity price of 18.44¢/kWh as of May 2026, using the formulas shown above. We do not claim
hands-on measurement of these devices. Standby figures are typical published ranges rather than a
single sample, and your own devices, rate and usage will shift the totals — the method is the
part worth keeping.

Frequently asked questions

How much does 1 watt cost per year?

About $1.62, running continuously, at the US average residential rate of 18.44¢/kWh. Multiply
by your device’s wattage for a 24/7 estimate, or use watts × hours per day × days ÷
1,000 × your rate for anything intermittent.

Is it worth unplugging chargers and appliances at night?

Generally no for small electronics. A phone charger with nothing attached costs roughly 16 to 81
cents a year. It is worth switching off anything with a display, motor or network radio you never use,
because those sit at 5–20 watts rather than fractions of a watt.

Do smart plugs actually save electricity?

Only when what they switch off draws considerably more than the plug’s own 1–2 watt idle
draw. On a single charger or LED lamp a smart plug is a net loss. On a power strip feeding a whole
desk or media cluster it can return roughly ten times its own consumption.

What uses the most electricity in a typical home?

Anything that makes heat or moves air — space heating, cooling, water heating and clothes
drying. A single space heater run through a winter can cost more than every screen, charger and
speaker in the house left on all year.

Why does a hair dryer cost less to run than a space heater?

Duty cycle. A hair dryer draws more watts but runs for about ten minutes a day, while a space
heater runs for hours. Annual cost depends on watts multiplied by hours, so runtime usually matters
more than the number on the label.

Can I plug a space heater into a smart plug or power strip?

Most manufacturers say no. A 1,500W heater is at or beyond the continuous-switching rating of many
plugs and strips, and the NEC limits continuous load on a 15-amp circuit to 1,440W. Plug heaters
directly into a wall outlet on a circuit that can carry them.

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