Appliance Wattage Calculator
Find the typical wattage of a household appliance and what it costs to run.
Last updated · View algorithm, constants and default inputs (JSON)
About this calculator
This estimate uses fixed typical wattages from the appliance table, not a meter reading or the appliance’s moment-to-moment draw. Entered hours and quantity determine energy use; costs use your USD/kWh rate and exclude fixed fees, taxes, and usage cycles.
Worked example
calculated with the default values below
Appliance Refrigerator (150 W) · Quantity 1 · Hours used per day 3 h · Electricity rate 0.17 USD/kWh Total connected wattage 150 W · Daily energy use 0.45 kWh · Monthly cost 2.30 USD · Yearly cost 27.92 USD
General background references
Disclaimer
These calculators provide planning estimates only. Building codes, wiring regulations and safety requirements differ by country and change over time, and nothing here replaces a licensed professional or a permit. For structural, electrical or gas work, follow local code and have the installation inspected.
Implementation source
This record describes the implementation used by this page. It is not independent validation. External references, when available, support only the stated formula or definition; estimates and custom rules retain their own assumptions.
Formula and variables
monthly = W_a × q ÷ 1000 × h × 30 × rate
- monthly
- monthly electricity cost
- W_a
- appliance wattage (from lookup table)
- q
- quantity
- h
- hours of use per day
- rate
- price per kWh
W_a comes from a built-in table (e.g. refrigerator 150 W, dryer 3000 W); yearly cost uses 365 days.
Frequently asked questions
Why can a water heater cost more to run than a refrigerator?
The model assigns 4,000 W to a water heater and 150 W to a refrigerator. At $0.17 per kWh, three hours of water-heater use costs $2.04 per day; 24 hours of continuous refrigerator draw at 150 W costs $0.61 per day. The refrigerator’s real compressor cycles, so its actual daily energy use may be lower. Adjust the hours and quantity inputs to reflect your appliances.