Estimate your home's cooling needs, compare SEER2 efficiency ratings, and see how much an AC upgrade might save on electricity.
Enter the size of your conditioned space and a few home details. We'll use a transparent, simplified sizing estimate, then model seasonal cooling electricity costs for two systems using their SEER2 ratings.
Air conditioners should be sized for a building's cooling load, not chosen from square footage alone. The calculator above is a starting point for comparing rough capacities and electricity-cost scenarios—not a professional HVAC design.
BTU per hour describes the rate at which cooling equipment can remove heat. A “ton” of air-conditioning capacity is 12,000 BTU per hour. A larger tonnage is not automatically better: equipment that is too large may cycle excessively and struggle with humidity control.
Windows, roof and wall insulation, duct conditions, shade, air leakage, occupancy, floor plan, and outdoor climate all influence the real cooling load. This tool deliberately uses approximate factors for climate, insulation, ceiling height, and sun exposure rather than claiming to calculate every variable.
SEER2 is a seasonal efficiency rating for qualifying cooling equipment. Higher SEER2 ratings generally mean less modeled electrical energy for the same amount of cooling. This comparison assumes both entries use the same SEER2 rating system. If the older equipment label only gives SEER, check for a comparable SEER2 value first.
Your utility rate, actual cooling demand, thermostat settings, indoor humidity, maintenance, equipment condition, installation quality, and climate can all change what you spend. The 5- and 10-year illustrations simply multiply the annual result. They are not quotes, guarantees, or net investment returns.
Step 1 — Rough cooling load: Floor area is multiplied by an illustrative climate factor of 18–26 BTU/h per square foot, then adjusted for insulation, ceiling height, and sun. A plus/minus 15% planning sensitivity band is shown; this band is not a measured uncertainty or professional sizing range.
Step 2 — Seasonal electricity: The estimated cooling load in BTU/h × user-entered equivalent full-load hours ÷ (SEER2 × 1,000) produces an approximate annual kWh figure. That figure is multiplied by the entered $/kWh rate for an estimated annual cooling electricity cost.
Step 3 — Savings: Subtract the upgraded system's modeled electricity cost from the existing system's modeled cost. The 5- and 10-year amounts hold electricity prices and usage constant.
This is a deliberately simplified educational model. It does not replace a load calculation under ACCA Manual J, appropriate equipment selection, or a qualified professional's assessment. U.S. Department of Energy guidance also cautions against oversizing.
No. Use this as a starting point for questions and budget discussions. A licensed HVAC professional should calculate the actual home load and select equipment using accepted engineering methods.
Check your utility bill for your total electricity charges and kWh consumption, or your utility's published tariff. A blended price can be estimated by dividing relevant variable electricity charges by the kWh used; fixed fees may make your actual marginal rate different.
They represent an annual amount of cooling energy expressed as though the system had operated at its rated load throughout those hours. They are a modeling assumption, not simply how long the thermostat calls for cooling.
The modeled result will show additional electricity cost rather than savings. Remember that repairs, replacement condition, and changes in equipment sizing may also affect actual consumption.
No. The calculator models only cooling electricity use under fixed assumptions. It does not account for heating, duct repairs, installation, rebates, financing, or maintenance.
