HVAC Sizing Calculator
Answer 5 quick questions to get your required BTU, tonnage, efficiency tier and installed cost range by state.
Your home
Where's the home?
We size to your state's dominant climate zone. Load rises in hotter zones.
Home envelope
These are set to typical. Adjust only if you know your home differs — then tap Next.
What system?
Your estimate
How this HVAC sizing calculator works
This tool runs a Manual J-lite cooling load: it starts from your square footage and climate zone, then adjusts for ceiling height, insulation, sun exposure, and windows to estimate the BTU and tonnage your home needs. It then targets an efficiency tier and prices the installed job for your state. It is a planning estimate — a licensed contractor should perform a full Manual J before installation.
Frequently asked questions
How many tons of AC do I need for my house?
As a rough guide, homes need about one ton of cooling per 400–600 square feet, but the exact figure depends on your climate zone, insulation, and windows. This calculator accounts for those factors instead of using square footage alone.
Is bigger AC better?
No. An oversized system short-cycles, cools unevenly, and removes less humidity. Correct sizing is more comfortable and more efficient than simply buying a larger unit.