Electricity Cost Calculator
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About Electricity Costs
“How much does it cost to run?” beats wattage every time — a 1,500 W heater sounds abstract, but $60 a month gets attention. The math is genuinely simple; what people lack are the two inputs: the appliance's real draw and their true per-kWh rate. Both are findable in minutes.
Enter the wattage (label, spec sheet, or a plug-in power meter), daily hours of actual use, and your rate. You get kWh per day and cost per day, month, and year. Run it per appliance and the mystery items on your bill sort themselves out fast — space heating and cooling almost always win.
Sizing the AC itself rather than running costs? That's the BTU Calculator
The kWh Formula
One conversion — watts to kilowatt-hours — and a multiplication:
kWh per day = watts × hours ÷ 1,000 Cost = kWh × rate ($/kWh) Month ≈ day × 30 · Year = day × 365
Worked example: a 1,500 W space heater running 8 hours a day uses 12 kWh daily — $2.04 a day at $0.17/kWh, $61.20 a month, $745 a year. The same math prices a 10 W LED bulb at 26 cents a month: wattage differences of 100× produce cost differences of 100×.
Typical Appliance Costs
Common wattages at typical daily use, priced at a $0.17/kWh example rate — every cost computed by this calculator's formula:
| Appliance | Typical draw | Daily use | Monthly cost |
|---|---|---|---|
| LED bulb | 10 W | 5 h | $0.26 |
| WiFi router | 5 W | 24 h | $0.61 |
| TV (LED, 55″) | 100 W | 4 h | $2.04 |
| Microwave | 900 W | 1 h | $4.59 |
| Window AC | 1,200 W | 3 h | $18.36 |
| Space heater | 1,500 W | 8 h | $61.20 |
The pattern: anything that makes heat or cold dominates. Electronics are cheap to run; resistive heating is expensive — a single space heater can out-cost every light in the house combined, many times over.
Finding the Real Numbers
Wattage: the label often shows the MAXIMUM draw, not typical use — a fridge labeled 700 W actually cycles its compressor and averages 100–200 W. For cycling appliances (fridges, AC, washers), a $15–25 plug-in kWh meter measures the truth over a day or week; for always-max devices (heaters, bulbs, kettles) the label is accurate.
Rate: divide your bill's total by its kWh to get the all-in rate — commonly 20–40% above the advertised supply rate once delivery and fees fold in. Time-of-use plans complicate it further (cheap nights, expensive late afternoons); if you're on one, run this calculator with the rate for the hours you'd actually use the appliance.
Frequently Asked Questions
How do I calculate an appliance's electricity cost?
Watts × hours per day ÷ 1,000 = kWh per day; multiply by your $/kWh rate. A 100 W device on 10 hours a day uses 1 kWh daily — about $5/month at $0.17/kWh. Enter your real rate above; it varies hugely by state.
How much does it cost to run a 1,500 W heater?
At $0.17/kWh: $0.255 per hour, so 8 hours a day runs about $61 a month. Space heaters are the classic bill-shock appliance — the thermostat cycling helps a little, but resistive heat is inherently expensive.
What uses the most electricity in a home?
Heating and cooling lead almost everywhere, followed by water heating, then fridges (small draw but 24/7) and dryers. Electronics and lighting are minor at modern efficiencies — chase the heat-makers first.
How do I find my real electricity rate?
Divide the bill's total amount by the kWh consumed that period. The result — the all-in rate including delivery, fees, and taxes — is usually well above the advertised supply rate, and it's the honest number for cost math like this.
Do appliances use power when switched off?
Many draw standby (phantom) power — commonly 0.5–10 W each for TVs, consoles, chargers, and anything with a remote or clock. Individually trivial, but a houseful can add up to a few dollars monthly; smart strips kill it where convenient.
Is 220/240 V cheaper to run than 120 V?
No — you pay for energy (kWh), not voltage. A 2,000 W appliance costs the same per hour on either voltage; higher voltage just moves the same power with less current. Efficiency differences between models are what change the bill.
Methodology. This calculator uses standard construction and material-estimation formulas. It is reviewed and maintained by the Vast Calculators editorial team.
Last updated · July 10, 2026
Results are estimates for general use; verify critical figures independently.