HVACSize

Manual J. Without the laptop.

HVACSize runs a residential HVAC load calculation right from your phone — no account, no subscription, works offline. Built for HVAC professionals who need accurate equipment sizing in the field, not rough guesses.

THREE MODES — PICK YOUR PRECISION

Simple — ZIP code + square footage. Ballpark sizing in 60 seconds. Moderate — Whole-house block load with construction details. ~5 minutes. Pro — Full ACCA Manual J 8th Edition methodology, the standard the industry runs on. ~15 minutes.

Switch modes anytime. Your data carries over.

RESULTS YOU CAN TRUST

Separate cooling and heating loads with full component breakdown AC tonnage and furnace BTU output sized to your actual load Manual S guidance for equipment selection Climate design conditions from ACCA/ASHRAE data Imperial or SI units — BTU/kW, ft²/m², °F/°C

BUILT FOR THE JOB SITE

Fully offline — no signal needed on site Save and manage unlimited projects Attach site photos to each calculation Export a branded PDF report with your company name, logo, technician, and legal disclaimer International support — use a ZIP code or pick any country and city

YOUR DATA STAYS YOURS

No account required, ever Nothing leaves your device Export all project data as JSON at any time

Stop oversizing. Stop undersizing. Right-size equipment — and back it up with a calculation.