Electricity Cost Calculator — What Does It Cost to Run?

Calculate the daily, monthly, and annual cost to run any appliance from its wattage, hours used, and electricity rate. Add devices for a household total.

July 9, 2026

Electricity Rate (¢ per kWh)

Default is the ~18¢/kWh US national average — use your own utility bill's rate for accuracy.

DeviceWattsHours Used / DayDaily Cost

$1.08

$0.216

Daily

$1.30

Monthly

$38.88

Annual

$473.04

Cost = (Watts ÷ 1,000) × Hours Used × $/kWh Rate. Refrigerator and other cycling appliances draw power intermittently, not continuously — the wattage shown is the running draw, so estimate hours as effective run time, not 24. Actual electricity rates vary enormously by state and utility (from roughly 12¢/kWh to over 46¢/kWh) and your real bill also includes delivery charges, taxes, and fees this estimate doesn't cover.

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Reference Values

Last verified: Jul 9, 2026

Category	Range	What It Means	Status
LED Light Bulb ★	8-12 watts	Typical A19 LED replacement for a 60W incandescent bulb — roughly 85% less draw for the same brightness.	★ Best
Refrigerator (running draw)	100-200 watts	This is instantaneous draw while the compressor is on, not average draw — fridges cycle on and off, so real-world usage is closer to 6-8 running hours per day, not 24.	Okay
Desktop Computer	150-250 watts	Varies widely with CPU/GPU load — idle draw is much lower than under gaming or rendering load.	Okay
Window AC Unit	900-1,200 watts	A single-room unit sized around 8,000-10,000 BTU/hr.	Poor
Central Air Conditioner	3,000-4,000 watts	Whole-home central AC draw while the compressor is actively running — one of the largest loads in a typical house.	Poor
Space Heater	1,200-1,500 watts	Most portable electric space heaters are fixed at 1,500W on their high setting, the practical maximum for a standard 15A household circuit.	Poor
Electric Water Heater	3,000-4,500 watts	Draw while the heating element is actively running, not continuous — a tank cycles based on hot water usage and standby heat loss.	Poor
US national average residential rate (2026)	17.9-18.8 cents/kWh	This calculator defaults to 18 cents/kWh. Actual rates vary enormously by state and utility — always use your own rate from a recent bill for an accurate estimate.	Good
Lowest state average (North Dakota) ★	≈12.35 cents/kWh	States with abundant low-cost generation (hydro, wind, coal) tend to sit well below the national average.	★ Best
Highest state average (Hawaii)	≈46.62 cents/kWh	Hawaii's isolated grid relies heavily on imported oil for generation, pushing rates to roughly 2.5x the national average.	Poor

Source: Device wattage ranges aggregated from typical US ENERGY STAR and manufacturer nameplate ratings. Electricity rate data from the US Energy Information Administration (EIA) Electric Power Monthly and Electric Choice's state-by-state electricity rate tracker.

Worked Examples

Space Heater, 8 Hours a Day

Device: Space Heater (1,500W)
Hours Used: 8 hrs/day
Rate: 18 cents/kWh

$2.16/day, $64.80/month, $788.40/year

(1,500 ÷ 1000) × 8 × $0.18 = 1.5 kWh × 8 × $0.18 = $2.16/day. ×30 = $64.80/month. ×365 = $788.40/year — space heaters are one of the most expensive common appliances to run for extended hours.

Window AC Unit, 10 Hours a Day (Summer)

Device: Window AC Unit (1,000W)
Hours Used: 10 hrs/day
Rate: 18 cents/kWh

$1.80/day, $54.00/month, $657.00/year

(1,000 ÷ 1000) × 10 × $0.18 = 1.0 kWh × 10 × $0.18 = $1.80/day. ×30 = $54.00/month. ×365 = $657.00/year — for the ~4 summer months it actually runs, that's closer to $216 for the season, not the full annual figure.

Refrigerator, Cycling ~8 Running Hours a Day

Device: Refrigerator (150W running draw)
Hours Used: 8 hrs/day (effective run time)
Rate: 18 cents/kWh

$0.22/day, $6.48/month, $78.84/year

(150 ÷ 1000) × 8 × $0.18 = 0.15 kWh × 8 × $0.18 = $0.216/day. ×30 = $6.48/month. ×365 = $78.84/year. The 150W is instantaneous compressor draw, not a 24-hour average — the compressor cycles on and off, so ~8 effective running hours per day is a realistic estimate, not 24.

LED Bulb, 5 Hours a Day

Device: LED Light Bulb (10W)
Hours Used: 5 hrs/day
Rate: 18 cents/kWh

$0.009/day, $0.27/month, $3.29/year

(10 ÷ 1000) × 5 × $0.18 = 0.01 kWh × 5 × $0.18 = $0.009/day. ×30 = $0.27/month. ×365 = $3.29/year — a single LED bulb costs about the same to run for a year as a fast-food drink.

Multi-Device Household Estimate

Devices: TV (100W, 4 hrs) + Desktop Computer (200W, 3 hrs) + Refrigerator (150W, 8 hrs) + 5 LED Bulbs (50W combined, 5 hrs)
Rate: 18 cents/kWh

$0.44/day, $13.23/month, $160.97/year combined

TV: 0.1×4=0.4 kWh. Desktop: 0.2×3=0.6 kWh. Fridge: 0.15×8=1.2 kWh. LED bulbs: 0.05×5=0.25 kWh. Total = 2.45 kWh/day × $0.18 = $0.441/day. ×30 = $13.23/month. ×365 = $160.97/year — this is how the running-total feature adds up several devices into one household estimate.

How to Use This Calculator

1

Set your electricity rate

Defaults to the 18 cents/kWh US national average — replace it with the rate from your own utility bill for an accurate result, since rates vary by more than 3x between states.
2

Pick a device preset or enter custom wattage

Choose from common household devices (LED bulb, space heater, window AC, refrigerator, and more) to auto-fill a typical wattage, then adjust the number if your specific appliance differs.
3

Enter hours used per day

For cycling appliances like refrigerators or water heaters, use effective running hours rather than 24 — the wattage shown is the draw while actively running, not a continuous average.
4

Add more devices for a household total

Use "+ Add Device" to stack multiple appliances — the calculator sums every valid row into one combined daily, monthly, and annual estimate.

What Each Value Means

Wattage (watts): The rate of power an appliance draws while running, measured in watts (W). Higher wattage means more energy consumed per hour of use.
Kilowatt-Hour (kWh) (kWh): The standard unit electric utilities bill by — the energy used by a 1,000-watt load running for one hour. A device's wattage divided by 1,000, multiplied by hours used, gives kWh consumed.
Electricity Rate ($/kWh): The price your utility charges per kilowatt-hour of energy consumed, typically shown on your bill in cents or dollars per kWh. This is the single biggest driver of state-to-state cost differences.

Frequently Asked Questions

How do I calculate the cost of running an appliance?

Divide the appliance's wattage by 1,000 to get kilowatts, multiply by the hours you use it per day, then multiply by your electricity rate in dollars per kWh. A 1,500-watt space heater run for 8 hours a day at 18 cents/kWh costs (1,500 ÷ 1,000) × 8 × $0.18 = $2.16 per day. Multiply the daily figure by 30 for a monthly estimate or 365 for an annual one.

What is the average electricity rate in the US?

The US national average residential electricity rate is roughly 18 cents per kWh as of 2026 EIA data (a confirmed range of 17.9-18.8 cents/kWh depending on the month). That average hides enormous state-by-state variation — North Dakota residents pay around 12.35 cents/kWh while Hawaii residents pay around 46.62 cents/kWh, nearly 4x more. Always swap in your own state or utility rate for an accurate estimate rather than relying on the national average.

Why does my refrigerator's wattage not match its actual running cost?

A refrigerator's wattage rating (often 100-200 watts) is the draw while the compressor is actively running, not a continuous 24-hour draw. The compressor cycles on and off throughout the day to maintain temperature, so a fridge might only run for a combined 6-10 hours out of 24. Using the full 24 hours in this calculator would overstate the real cost — use effective running hours instead, or check your specific model's kWh/year rating on its EnergyGuide label for the most accurate figure.

Why is my actual electric bill higher than what this calculator shows?

This calculator only estimates the energy-consumption portion of your bill — watts × hours × rate. A real electric bill also includes delivery or transmission charges, fixed customer/connection fees, taxes, and sometimes demand charges or seasonal rate tiers, none of which scale directly with a single appliance's usage. Treat this tool's output as your appliance-level usage cost, not a prediction of your total monthly bill.

Which household appliances cost the most to run?

Heating and cooling equipment dominates most electric bills — central air conditioners, electric space heaters, and electric water heaters all draw 1,500-4,500 watts and run for hours at a time. By contrast, electronics and LED lighting (TVs, laptops, LED bulbs) typically draw under 200 watts and cost only pennies to run per day even with heavy use. If you're trying to lower a bill, the biggest wins usually come from reducing high-wattage heating/cooling runtime, not unplugging small electronics.