ManualJ Lite

Simplified Manual J HVAC load calculation — get cooling and heating BTU estimates for any climate zone.

ManualJ Lite is a fast, offline HVAC load calculator based on the Manual J simplified method. Enter your building details and instantly get cooling and heating load estimates for proper equipment sizing.

WHAT IT CALCULATES:

Cooling Load:

• Sensible and latent cooling loads (BTU/h)
• Total cooling capacity required
• AC tonnage recommendation
• Load breakdown by component

Heating Load:

• Total heating BTU/h
• Heat loss through walls, windows, roof
• Infiltration losses
• Recommended furnace capacity

BUILDING INPUTS:

• 7 IECC climate zones (Zone 1 through Zone 7)
• Floor area in square feet
• Insulation quality (Poor, Average, Good, Excellent)
• Window type (Single, Double, Low-E Double, Triple)
• Number of stories and orientation

KEY FEATURES:

• Simplified Manual J calculation method
• Cooling and heating mode toggle
• Component-level load breakdown percentages
• Instant results as you adjust inputs
• Clean, easy-to-read results layout
• Works completely offline
• No account or login required

BUILT FOR HVAC TECHS:

Whether you are an HVAC technician, contractor, or homeowner planning a system upgrade, ManualJ Lite gives you quick load estimates for equipment sizing. Select your climate zone, enter building specs, and get BTU and tonnage results in seconds.

Covers all 7 IECC climate zones with appropriate design temperatures for accurate residential load calculations.