HVAC Load Calc: Manual J
Heating & cooling calculator
About
Estimate a home's heating and cooling loads with a simplified block calculation. Input house details like area, insulation, and windows to see load breakdowns and check equipment against your quotes. Save, sync, and share detailed reports via PDF.
What's New in HVAC Load Calc
1.2.3
October 26, 2026
This update changes only how the app is listed on the App Store. Nothing in the app itself has changed.
Subscriptions & In-App Purchases
HVAC Load Pro
Manual J load calcs, saved jobs, PDF reports
Events
Test a furnace, AC or heat pump against the load
Oct 14, 2026 — Nov 13, 2026
Developer apps
FAQ
What is HVAC Load Calc?
HVAC Load Calc is a utility app designed to estimate a home's heating and cooling loads using a simplified block calculation method. It helps users input house details, see load breakdowns, and check equipment against their quotes.
How does HVAC Load Calc calculate loads?
The calculation uses textbook ASHRAE heat transfer principles for envelope conduction, infiltration, and solar/internal gains. It also incorporates duct losses and blower door results for a comprehensive estimate.
What information can I input into HVAC Load Calc?
You can input floor area, ceiling height, stories, ZIP code for weather data, design temperatures, insulation values, window details, air tightness, duct information, and occupant numbers.
Can HVAC Load Calc be used for certified Manual J calculations?
No, HVAC Load Calc provides a simplified whole-house block calculation for initial estimates. For certified room-by-room Manual J calculations, a separate, more detailed calculation is required.
How does HVAC Load Calc handle subscriptions and trials?
New subscribers receive a free 7-day trial. After the trial, a subscription is required to access all features of HVAC Load Calc.
What devices does HVAC Load Calc support?
HVAC Load Calc is available on iPhone and iPad devices. On iPad, it offers a split-screen view for the form and report.
How often is HVAC Load Calc updated?
The app was last updated on October 15, 2026, with version 1.2.2. This indicates a recent update, suggesting ongoing development and support.
Does HVAC Load Calc have ads?
No, HVAC Load Calc does not contain advertisements. The app is ad-free, focusing on providing a clean user experience for its calculations.
