About Hvac Sizing Calculator

Hvac Sizing Calculator is a free tool built to answer one question well: what size heating and cooling system does a home actually need? Sizing is one of the most consequential — and most frequently botched — decisions in a heating and air-conditioning project, and good information about it is surprisingly hard to find without a sales pitch attached.

Who builds this

This site is maintained by Marcio, an independent tools builder. It is not affiliated with any equipment manufacturer or contractor, and it does not sell HVAC equipment or installation. That independence is the point: the calculator’s job is to give you a neutral starting number and to explain the reasoning, so you can evaluate professional quotes as an informed buyer.

How the estimates are made

The calculator uses published BTU-per-square-foot load factors organized by U.S. climate zone, then adjusts for ceiling height, insulation quality, sun exposure and internal heat gains from occupants and kitchens. Cooling is reported in tons (12,000 BTU/hr each) and heating in furnace output BTU with input ratings at common efficiencies. The methodology is described in full in our sizing guide, and we are candid about its limits: it is a planning estimate, not a substitute for a contractor’s Manual J load calculation.

Our goal

We want every visitor to leave with a realistic number, an understanding of what drives it, and the confidence to ask a contractor the right questions. If the tool helped you, or if you spotted something we can improve, we would like to hear from you on the contact page.