HCLHVAC Cost Lab

Calculators / Operating cost

Updated Jul 26, 2026 · Method and source links reviewed

Operating cost

Window AC Running Cost Calculator

Estimate how much a window or portable air conditioner adds to your electric bill.

Your planning inputsUpdates automatically
watts
Use the label input watts, not cooling BTU/h.
hours/day
Compressor runtime, not just time switched on.
Number of cooling days in the month.
$/kWh
Use your variable all-in rate.

Estimated result

$39/month

216 kWh per modeled month; approximately $156 across a four-month cooling season.

How to use this estimate

  • Actual compressor cycling can make measured use lower than a full-load estimate.
  • A plug-in energy meter can replace the nameplate estimate with measured kWh.
  • Portable single-hose units may use more energy for the same comfort than a well-sealed window unit.

Transparent method

We expose the planning formula so you can challenge it and replace assumptions with local evidence.

watts ÷ 1,000 × runtime hours × days × electricity rate

What this calculator cannot see

  • Fixed utility charges are excluded.
  • Do not exceed outlet, circuit, or extension-cord ratings.

Professional verification

Use this result to prepare questions and compare scenarios. Final equipment selection, electrical work, refrigerant work, combustion, duct design, and permitting should be handled by qualified professionals following local codes and manufacturer instructions.