Our calculation standard
We use ordinary energy arithmetic and reference established consumer guidance from sources such as the U.S. Department of Energy and ENERGY STAR. Each calculator page links to its primary guidance and displays the formula used.
Inputs matter more than defaults
Default values are examples, not claims about your home. For better estimates, replace them with your electricity rate, product wattage, vehicle efficiency, actual runtime, or measured energy use.
Why actual bills may differ
Household energy use changes with climate, utility rate structures, equipment condition, thermostat settings, installation, occupancy, and behavior. Some devices cycle on and off rather than drawing their rated power continuously.
Verification process
- Formulas are separated into reusable calculation functions.
- Units are converted explicitly before costs are calculated.
- Representative inputs are tested against hand calculations.
- Assumptions and source links appear beside each calculator.
- Safety-critical engineering and code-compliance calculations are excluded.
Planning estimates only
Results are educational planning estimates, not professional energy audits, engineering advice, quotes, warranties, or guarantees. Confirm product requirements with the manufacturer and consult a qualified professional before making a major purchase or modification.