Electricity Cost Calculator (Appliance kWh)
Enter an appliance’s wattage, daily usage hours, and your electricity rate. See what it really costs on the bill — some results surprise.
| Per day | — |
| Per year | — |
| Energy used | — |
The electricity cost formula
Cost = Watts × Hours ÷ 1000 × Rate per kWh
The default example is the classic shock: a 1500W space heater running 6 hours/day costs about $46/month — often more than the room is worth heating. Meanwhile a 9W LED bulb at the same hours costs 28 cents/month. Wattage × hours is everything.
What things actually cost to run (at $0.17/kWh)
| Appliance | Typical monthly cost |
|---|---|
| Space heater (1500W, 6h/day) | ≈ $46 |
| Central AC (3500W, 8h/day summer) | ≈ $143 |
| Refrigerator (~150W average draw) | ≈ $18 |
| Gaming PC (400W, 4h/day) | ≈ $8 |
| TV (100W, 5h/day) | ≈ $2.60 |
| Phone charging | ≈ $0.15 |
Where the savings actually are
Heating, cooling, and hot water dominate home energy — the small stuff (chargers, standby lights) is rounding error. Rank by this calculator before unplugging toasters: one degree on the thermostat beats a hundred vampire devices. For efficiency upgrades, the payback calculator answers whether the new appliance earns its price.
Frequently asked questions
How much does a space heater cost to run?
A 1500W heater at $0.17/kWh costs about 26 cents per hour — $46/month at 6 hours/day. Electric resistance heat is among the most expensive heat there is.
How do I calculate appliance running cost?
Watts × hours ÷ 1000 = kWh, × your rate. A 100W TV for 5 hours: 0.5 kWh ≈ 8.5 cents/day.
What uses the most electricity at home?
HVAC (heating/cooling) at 40–50%, water heating ~15%, then fridge, laundry, and lighting. Electronics and chargers are single-digit percentages.
Is standby power worth worrying about?
Modern standby is 0.5–2W per device — pennies monthly each. A whole house of vampires might cost $5–10/month; the thermostat and water heater dwarf it.
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Last updated: 2026-07-08