HVAC Sizing & BTU Calculator

How to calculate BTU requirements?

BTU sizing involves calculating the volume of a room and adjusting for heat gain from windows, people, and insulation quality.

Formula: BTU = (Area × Height × Insulation Factor) + (Occupants × 600)

Using the HVAC calculator: an example

Example: A 500 sq ft room with 10ft ceilings, average insulation, and 2 occupants.

Step-by-step calculation:

• Calculate volume: 5,000 cubic feet
• Apply base multiplier for climate zone
• Add 1,200 BTUs for two occupants
• Adjust for window heat gain (+1,000 per window)

Frequently Asked Questions

What is AC Tonnage?

One 'ton' of air conditioning is equal to 12,000 BTUs per hour of cooling capacity.

What happens if I undersize my HVAC?

An undersized unit will run constantly, failing to reach the target temperature and increasing energy bills.

Is this a Manual J calculation?

No, this is an estimate. Professional installers use a 'Manual J' load calculation for precise equipment matching.