HVAC Load Calculator Manual J
HVAC Load Calculator Manual J Summary
HVAC Load Calculator Manual J is a free, with in-app purchases iOS app in Tools by Mike Watson. Released in Feb 2026 (6 months ago). It has 31 ratings with a 4.67★ (excellent) average. Based on AppGoblin estimates, it reaches roughly 216 monthly active users and generates around $<10K monthly revenue (100% IAP / 0% ads). Store last updated Aug 1, 2026
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HVAC Load Calculator Manual J SDKs Summary
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4.67★
Ratings: 31
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App Description
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
Unlike expensive desktop software shoehorned onto mobile, we designed this from scratch for techs working in the field. Large buttons you can tap with gloves on. Fast calculations while standing in a basement. Professional reports that win homeowner trust.
THREE LEVELS OF ACCURACY
Simple Mode – 8 inputs
Regional ZIP-code benchmarks and square-footage multipliers. 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) – 15 inputs
Component-level factors: insulation quality, window types, foundation — with a conservative safety buffer. Prevents undersizing while staying accessible for non-engineers. The sweet spot for standard replacement jobs.
Pro Mode – Professional Grade (Detailed Whole-House Block Load) – 16 inputs + pro overrides
Full MJ8 physics: altitude-adjusted density, solar load factors, CLTD daily-range lag, and separated duct analysis. Maximizes equipment life and comfort — often right-sizing by 1+ ton. Best for new construction, high-performance builds, and detailed equipment sizing.
NOW AVAILABLE WORLDWIDE
US Mode – ZIP code lookup backed by a climate database covering nearly 28,000 ZIP codes
International Mode – Enter your city, country, and local design temperatures directly — no ZIP code required. Choose your climate zone and moisture regime, and the calculator handles the rest.
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 r