Electricity Cost Calculator
What any appliance costs to run: watts × hours × your kWh price — daily, monthly and yearly.
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How Consumption and Cost Are Calculated
Energy use follows one formula: consumption (kWh) = power (W) × time (h) ÷ 1000, and cost = consumption (kWh) × your price per kWh. A 2,000 W heater run for 5 hours uses 2000 × 5 ÷ 1000 = 10 kWh; at $0.15/kWh that's $1.50 for the day, roughly $45/month if run daily. The tool scales this same pair of formulas to daily, monthly and yearly totals so appliances can be compared directly.
Worked example — the hidden cost: a microwave's clock, a TV left "off" with its standby LED lit, and a phone charger left plugged into an empty socket each typically draw about 1-10 W even while doing nothing useful — so-called standby or "phantom" load. A single 5 W phantom draw running continuously (24 h × 365 days) works out to 5 × 24 × 365 ÷ 1000 = 43.8 kWh a year — small next to a heater, but multiply that by a dozen always-plugged-in devices around a home and it adds up to roughly 100-200 kWh a year, quietly padding every bill without ever appearing as a deliberate "on" decision.
What to Know
- Nameplate wattage is a ceiling, not the real average. Cycling appliances (fridges, ACs, washing machines with heating elements) draw their rated power only in bursts; average draw often runs 30-70% of the label figure — a plug-in energy meter measures actual use, the label only measures the maximum.
- The big four dominate a home's bill: space heating/cooling, water heating, refrigeration and clothes drying/washing — these generate real heat or run motors continuously, dwarfing anything purely electronic.
- Your real kWh price usually beats the advertised rate. Divide your total bill by total kWh used to capture delivery fees and taxes bundled in — often noticeably higher than the headline energy-only price.
- Standby load is easy to eliminate but easy to ignore. A power strip switch, or simply unplugging chargers and TVs when truly not in use, removes that always-on draw entirely — the saving is small per device but consistent every single day of the year.
Frequently Asked Questions
Where do I find my kWh price?
On your bill: total charges ÷ kWh used gives the true all-in rate including fees — usually noticeably above the advertised energy-only rate.
Does a 2000 W AC really draw 2000 W all the time?
No — compressors cycle and inverters modulate. Expect 40-70% of rated power averaged over a summer day; the calculator's hours field can reflect that (e.g. enter 6 h of compressor time for 10 h of use).
How much does standby ("phantom") power actually cost per year?
A single 5-10 W idle device running 24/7 uses roughly 44-88 kWh a year. Across a dozen always-plugged-in devices (chargers, set-top boxes, microwaves, TVs on standby) that adds up to about 100-200 kWh a year — at $0.15/kWh, somewhere around $15-30 annually, spent on devices doing nothing useful.
Why doesn't my calculated cost match my actual bill?
This tool prices one appliance in isolation. Real bills also include every other device running at the same time, tiered or time-of-use pricing that changes the per-kWh rate at different usage levels, and fixed charges (delivery, standing charge, taxes) that apply regardless of consumption.
Does running an appliance longer at lower power use less energy than running it briefly at full power?
Not necessarily — energy is power × time, so the two can trade off exactly. This is why inverter-driven ACs and fridges, which modulate power instead of cycling fully on/off, can use less total energy over a day even though they run for more hours: sustained low power often beats repeated bursts of high power.
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