· so, how do you determine what size furnace you need ? Learn how to calculate the size of furnace you need based on your home square footage and climate zone. Hvac. com explains what goes into furnace sizing and the many factors that ultimately influence the size furnace your home requires. Let us help you find the right product. How do i use the furnace size calculator? How do you know if a furnace is a good size? What size furnace do you need for a 3,000 sq ft home? This furnace size calculator, or furnace btu calculator, will help you determine what size of furnace you need for any room area, insulation type, or outdoor temperature. Use the online tool to estimate the btu and tonnage of furnace for houses from 500 to 3,000 sq ft. · this furnace size calculator uses your house size, climate (see the map below) and other important information to tell you what size furnace your home needs to keep it warm without wasting energy. What size furnace do i need? · in this guide, we’ll walk you through the key factors used in furnace sizing and how to estimate the correct btu output for your home. · choosing the right furnace size doesn’t have to be complicated. The size of a furnace refers to its heating output, measured in btus (british thermal units) per hour. See an estimate of what size furnace you need. Wide selection in stock and ready to ship with quick & free delivery. · if youre wondering, what size furnace do i need ? use this guide to help with your research. Call our us heating and cooling experts today! What does “ furnace size ” mean? Mark callahan explains how to determine the perfect btu rating for your home using real-world data and pro-level tips.