π Appliance Energy Cost
What that appliance really costs to run.
The Simple Math Behind Your Bill
Every appliance's cost comes from one formula: watts x hours / 1000 x your rate. A 1,500-watt space heater running 2 hours a day at 17 cents per kWh costs 1500 x 2 / 1000 x 0.17 = $0.51 a day, $15.30 a month, $183.60 a year. Enter any three numbers and the calculator does the rest, with presets for common appliances so you do not have to look up wattages.
The US average residential rate is around 17 cents per kWh, but it ranges from under 10 cents in parts of the South and Northwest to over 30 in California and Hawaii. Check your bill for your real rate: it is the number that makes every other calculation honest.
Where the Money Really Goes
Heating and cooling dominate: a central AC at 3,500 watts running 8 hours a day costs about $4.76 daily at average rates, over $140 a month in summer. Space heaters are the sneakiest: that cozy 1,500-watt heater costs more per hour than almost anything else in the house. Always-on loads add up silently: a 300-watt gaming PC left on 24/7 costs $37 a month doing nothing.
Cutting the Cost
The biggest wins are the biggest loads: raise the AC a few degrees, use fans, and seal drafts. Swap the five most-used bulbs to LED (60W to 10W saves about $30 per bulb per year at 3 hours daily). Kill standby loads with power strips. And compare before you buy: a more efficient appliance often pays for itself, which our LED savings calculator shows in detail.
The Vampire Load Problem
Many devices sip power all day while doing nothing: cable boxes, game consoles, older TVs, and anything with a warm power brick. Standby loads of 5 to 10 watts sound trivial, but ten such devices cost $40 to $90 a year at average rates. A smart power strip that cuts peripherals when the main device sleeps pays for itself quickly on entertainment centers and home offices. The worst offenders are DVRs and cable boxes that never truly sleep: if yours runs hot to the touch while off, it is costing you real money. Unplugging phone chargers helps too, though modern ones draw under a watt: focus first on the boxes that stay warm.
Frequently Asked Questions
How do I calculate appliance electricity cost?
Watts x hours per day / 1000 x your $/kWh rate = daily cost. Multiply by 30 for monthly. A 1,500W heater at 2 hours/day and $0.17/kWh costs $0.51/day.
What uses the most electricity in a home?
Heating and cooling, by far: central AC and electric heat can each top $100/month in season. Water heaters, dryers, and space heaters are next.
How much does it cost to leave a TV on all day?
A modern 55-inch LED TV (~60W) at 24 hours costs about $0.24/day or $7/month at average rates. An old plasma at 300W would be five times that.
What is a kWh?
A kilowatt-hour: running 1,000 watts for one hour. Your utility bills you per kWh, currently averaging about $0.17 in the US.
Do phone chargers use much electricity?
Almost nothing: about 5 watts while charging, pennies per month. The bigger standby culprits are cable boxes, game consoles, and anything with a clock display.