Practical numbers for everyday decisions
Know what your home costs before you spend.
Run the numbers on energy, repairs and backup power—using your home, your rate and your habits.
Portable AC
- Power draw
- 1,200 W
- Daily use
- 8 hours/day
- Electricity rate
- $0.18 /kWh
- Days used
- 30 days
Three useful starting points
Start with a decision.
Each calculator exposes the assumptions, keeps the math visible and gives you a result you can change—not a generic national average.
Turn watts, daily use and your electricity rate into a clear monthly and annual cost.
02Repair or replaceCompare a repair quote with replacement cost, remaining life and five years of energy use.
03Backup powerEstimate usable battery capacity and realistic runtime after efficiency losses and reserve.
Appliance energy cost
Use the power label on your appliance and the electricity rate shown on your bill.
Formula: watts ÷ 1,000 × hours per day × days × electricity rate. Cycling appliances and variable-speed equipment can use less than their full rated power.
Method before recommendation
Transparent inputs. Useful ranges. No hidden score.
Electricity calculations use the standard relationship between watts, operating time and kilowatt-hours. Your bill remains the best source for your actual rate.
Repair and runtime estimates are planning tools, not guarantees. We show the assumptions so you can pressure-test the result before making a purchase.
Popular household questions
Use a calculator built for the job.
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Humidity cost guide
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Ventilation cost guide
How much does a window fan cost to run all night?
Appliance decision guide