Size your HVAC system before contractors quote you
Enter four details, get a BTU load estimate in seconds — then compare real quotes instead of guessing.
HVAC Load Calculator
Typically within ±10% of Manual J for most single-family homes.
Your load estimate
Your cooling load is ready below. Email unlocks heating load, recommended size, and the oversizing check.
The number above is your real free estimate — email unlocks the locked rows.
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See heating + cooling loads, recommended equipment size, and the oversizing warning — free.
Your full sizing report
The Contractor-Ready Load Report Pack
Walk into quotes like an engineer. Full printable report, contractor comparison sheet, and negotiation scripts.
- Detailed printable load report (PDF, all inputs adjustable)
- 3-quote comparison spreadsheet with fair-price ranges by zone
- Questions-to-ask cheat sheet that exposes oversizers
- Rebates & tax-credit finder for your state
HVAC load questions
How accurate is this estimate?
For most single-family homes it lands within ±10% of a full ACCA Manual J. Unusual layouts, vaulted ceilings, or heavy glazing can push it further off — a contractor should always verify on-site before you buy.
Why does oversizing matter?
An oversized system short-cycles: it cools fast but leaves the air humid and wears itself out early. Correctly sized equipment runs longer, dehumidifies better, and lasts longer.
What inputs matter most?
Square footage and climate zone dominate, then insulation quality and window count. Sun exposure shifts the load a notch for south- and west-facing glass.
What is a "ton" of cooling?
12,000 BTU/h. A typical 2,000 sqft home in a mixed climate needs about 2.5–3 tons — but never buy by rule of thumb alone.