Tools & Calculators
What size HVAC do you need?
Contractors sell oversized systems because it feels safe — but a too-big unit short-cycles (switches on and off too often), leaves your home clammy, and wears out early. Start here for an honest ballpark by square footage and climate, then see the certified units that fit. The exact answer is a Manual J load calculation — we explain why below, and it matters.
How it's computed. Cooling ≈ square footage × a per-sq-ft factor for your climate zone; heating ≈ square footage × a (larger) cold-climate factor, adjusted for insulation and ceiling height. We then round cooling to the nearest half-ton and show a range, because a rule of thumb is a range. What it can't see — your windows and their orientation, actual air-sealing, duct leakage, shading, and how many people live there — is exactly what a Manual J load calculation measures, and it's the only defensible way to size equipment (ACCA Manual J; ENERGY STAR, energy.gov). Use this to sanity-check a contractor's number — if their proposal is a ton bigger than this with no load calc to back it, ask why. Full method in our methodology.
What that size costs installed → Will a heat pump keep up in the cold? →