HVAC Sizing Calculator
Calculate the right size heating and cooling system for your home. Get BTU and tonnage recommendations based on square footage, climate zone, insulation, and other factors.
Home Details
Conditioned living space
Windows & Occupancy
Design Temperatures
Hottest expected outdoor temp
Coldest expected outdoor temp
For operating cost estimate
HVAC Sizing
Proper HVAC sizing is crucial. An oversized system short-cycles, wasting energy and failing to dehumidify. An undersized system runs constantly and can't maintain comfort.
- • 1 ton = 12,000 BTU/hr cooling
- • Rule of thumb: ~400-600 sq ft per ton
- • Manual J is the industry standard calculation
How to Use
- Enter your home's square footage and ceiling height
- Select your climate zone and insulation level
- Add window count, occupants, and sun exposure
- Set design temperatures for your area
- Click Calculate to get your recommended system size
FAQ
What is a design temperature?
Design temperatures are the extreme outdoor temperatures your HVAC system should handle. For cooling, use your area's hottest expected temperature. For heating, use the coldest. These aren't record highs/lows but typical extremes (99% design conditions).
Is bigger always better for AC?
No! Oversized AC units cool quickly but don't run long enough to remove humidity, leaving your home clammy. They also cycle on/off frequently, wearing out components faster. Proper sizing is more important than maximum capacity.
What is Manual J?
Manual J is the industry-standard method for calculating residential heating and cooling loads, published by ACCA. It accounts for building materials, orientation, windows, infiltration, and local climate data. This calculator provides a simplified estimate; a professional Manual J calculation is recommended for accuracy.