Electricity Cost Calculator
Enter an appliance's wattage and how you use it — the cost updates as you type, and the link in your address bar always reflects your numbers.
How this calculator works
Electricity is billed by the kilowatt-hour (kWh) — the energy used by a 1,000-watt load running for one hour. To get the daily cost, we convert the appliance's wattage to kilowatts (divide by 1,000), multiply by the hours it runs each day, then multiply by your rate per kilowatt-hour. From there, the monthly figure is the daily cost × 30 and the yearly figure is the daily cost × 365 — simple multiplication, but it adds up faster than most people expect for anything left running for hours at a time. This tool only counts active-use hours at the one rate you enter; it doesn't model standby power or tiered/time-of-use pricing (see the FAQ below).
Worked example
A 1,500 W space heater run 4 hours a day at a rate of $0.15/kWh: that's (1,500 ÷ 1,000) × 4 × $0.15 = $0.90 per day. Over a month that's $0.90 × 30 = $27.00, and over a year it's $0.90 × 365 = $328.50 — a useful reminder that a modest-looking daily cost compounds into a real line item on your annual utility spend.
Frequently asked questions
Where do I find my appliance's wattage?
Check the label on the appliance itself — most have a small metal or printed plate on the back, bottom, or near the power cord listing wattage (W) directly, or volts and amps you can multiply together to get watts. If the label's worn off or hard to find, the manual or the manufacturer's spec sheet for your exact model usually lists it too.
Where do I find my real electricity rate?
Your utility bill is the most accurate source — look for a line listed in $/kWh or cents/kWh (divide cents by 100 to get dollars). Keep in mind some utilities charge tiered rates that increase after a certain usage threshold, or time-of-use pricing that's higher during peak hours, and this simple calculator only uses the one flat rate you enter, so treat the result as an estimate rather than a bill-accurate figure.
Does this include standby or 'phantom' power?
No — this only counts the hours you tell it the appliance is actively running. Many electronics and appliances draw a small trickle of power even when switched off or idle (often called phantom or standby power), and that's outside the scope of what this calculator estimates.
How can I lower the cost this calculator shows me?
A few general levers: reduce the hours the appliance actually runs, especially for anything you can schedule flexibly; if your utility uses time-of-use pricing, running heavy loads during off-peak hours can lower your effective rate; and unplugging or switching off appliances you're not using cuts both active and standby draw. None of this is specific to any one appliance — it's just where to start looking.