HVAC Load Calculator Manual J

The Manual J HVAC Load Calculator is the one HVAC contractors actually want to use.

Stop overpaying for clunky, over-engineered calculators designed for engineers. HVAC Load Calculator brings professional Manual J calculations to your iPhone or iPad — clean, modern, offline-ready, and built for the field.

BUILT FOR HVAC PROFESSIONALS
Designed from scratch for techs in the field: large buttons you can tap with gloves on, fast calculations in the basement, and professional reports that win homeowner trust.

THREE LEVELS OF ACCURACY
Simple Mode
Sized from your ZIP code's design conditions and the home's floor area. Get an estimate in under 60 seconds with zero measurements. Perfect for quick quotes and initial sales conversations.

Moderate Mode – Standard Accuracy (Whole-House Block Load)
Component-level factors: insulation quality, window types, foundation. The sweet spot for standard replacement jobs.

Pro Mode – Professional Grade (Detailed Whole-House Block Load)
Full MJ8 detail: per-direction window solar, measured airtightness, window ratings, overhang shading, and duct analysis. Maximizes equipment life and comfort — often right-sizing by 1+ ton. Best for new construction, high-performance builds, and detailed equipment sizing.

MEASURE ROOMS WITH LiDAR — NEW
On LiDAR-equipped iPhone and iPad Pro models (iOS 16+), walk each room and the app measures it for you — floor area, ceiling heights, windows, and exterior walls flow straight into your load calculation. Review each room, adjust with a tap, apply. Your PDF now includes a Room Measurements chapter with a sketch of each scanned room.

NOW AVAILABLE IN US AND CANADA
US Mode – ZIP code lookup backed by a climate database covering nearly 28,000 ZIP codes
Metric Units – Toggle between Imperial and SI (kW, m², m³/h) throughout the app and PDF reports

WORKS IN THE FIELD
Offline-First – No signal in the basement? No problem. Everything runs locally on your device.
Auto-Save Projects – Every calculation saves automatically. Never lose your work.
iCloud Sync – Start a job on your iPhone, finish it on your iPad. Projects sync automatically across your devices.
Professional PDF Reports – Generate and share detailed load reports from your phone or tablet. Add client name, site address, and job number — every report is stamped with a revision number and date, so everyone knows it's