How to Calculate Appliance Electricity Cost
The formula is simple: kWh = watts ÷ 1,000 × hours used, then multiply by your rate. In plain terms:
- Find the appliance wattage on its label (back or bottom), manual, or search the model number
- Multiply by hours used per day → watt-hours
- Divide by 1,000 → kilowatt-hours (kWh)
- Multiply by your electricity rate ($/kWh) → daily cost
Worked example: A 1,500-watt space heater running 8 hours a day at $0.16/kWh: (1,500 × 8) ÷ 1,000 × 0.16 = $1.92/day, about $57.60/month, or $700/year. That's why running heaters and dryers "just for a bit" adds up so fast.
Common Appliance Running Costs (8 hrs/day, $0.16/kWh)
| Appliance | Watts | Daily | Monthly | Yearly |
|---|---|---|---|---|
| LED Bulb (60W equiv.) | 9W | $0.01 | $0.35 | $4.20 |
| Laptop | 50W | $0.06 | $1.92 | $23.36 |
| Refrigerator (avg, 24h) | 150W | $0.58 | $17.28 | $210 |
| TV (55") | 80W | $0.10 | $3.07 | $37 |
| Washing Machine | 500W | $0.64 | $19.20 | $234 |
| Window AC | 1,200W | $1.54 | $46.08 | $560 |
| Space Heater | 1,500W | $1.92 | $57.60 | $700 |
| Clothes Dryer | 3,000W | $3.84 | $115 | $1,400 |
| Central AC (3 ton) | 3,500W | $4.48 | $134 | $1,636 |
| EV Charger (L2) | 7,200W | $9.22 | $277 | $3,365 |
Vampire Power: The Energy Drain You Don't See
Vampire power (standby power) is electricity consumed by appliances even when they're "off" but still plugged in. TVs, game consoles, phone chargers, and smart home devices draw 1-15 watts each while idle. With 20-40 such devices in a typical home, the US Department of Energy estimates standby power costs the average household $100-$200 per year.
How to fight it:
- Plug entertainment systems into a smart power strip and switch it off when not in use
- Unplug chargers when nothing is charging (they still draw power)
- Use the calculator above with 0 hours to see what a device costs plugged-in-but-idle
- Choose Energy Star certified devices — they have lower standby draw
The Biggest Electricity Users in a Typical Home
Knowing the top consumers helps you target your savings where it matters:
- Central AC — 3,500W, the summer bill driver
- Electric water heater — 4,000W, runs daily
- Clothes dryer — 3,000-5,000W per load
- Electric furnace — up to 10,000W in winter
- EV charger — 7,200W, but only when charging
Notice the refrigerator is the sneaky one: it's only 150W average (it cycles on and off ~35-40% of the time) but runs 24/7, costing more annually than your TV, laptop, and most small appliances combined.
5 Quick Tips to Cut Your Electricity Bill
- Air-dry clothes when possible — dryers are $100+/month users
- Set AC to 78°F (26°C) in summer — each degree below saves 3-5%
- Wash in cold water — heating water is 90% of washer energy
- Kill vampire loads — smart strips can save $50-100/year
- Compare rates — switching providers or plans can cut 10-20%
Frequently Asked Questions
How do I calculate appliance electricity cost?
kWh = watts ÷ 1,000 × hours; cost = kWh × rate. Example: 1,500W × 8h ÷ 1,000 × $0.16 = $1.92/day.
How much does it cost to run a refrigerator per month?
Modern fridges use ~150W average and run 24/7: about $17.28/month or $210/year at $0.16/kWh.
What is vampire power?
Standby power drawn by plugged-in "off" devices. The average home loses $100-$200/year to it.
Which appliances use the most electricity?
Central AC (3,500W), electric water heater (4,000W), and clothes dryer (3,000W+) are the top three; the fridge is sneaky because it runs all day.
How do I find my electricity rate?
It's on your utility bill as "energy charge" or "rate per kWh". US average is ~$0.16/kWh; Hawaii is ~$0.38, Louisiana ~$0.10.
How do I find appliance wattage?
Check the nameplate label, owner's manual, or search the model number. For cycling appliances (fridge, AC), use average wattage or multiply nameplate by duty cycle.
Methodology & sources: Formula: cost = (watts × hours) ÷ 1,000 × rate. Appliance wattage figures are typical values; actual wattage varies by model and age. Rates: US EIA average retail price of electricity (~$0.16/kWh, 2025-2026). Vampire power estimate: US Department of Energy standby power guidance. Estimates only — check your bill for exact rates and charges.