Heat Load Calc HVAC

About

HVAC Heat Load BTU Calculator helps HVAC technicians, engineers, and contractors calculate accurate cooling and heating loads. Calculate accurate cooling and heating loads using a simplified ACCA Manual J methodology based on room dimensions, insulation levels, window types, and ASHRAE climate zones - the industry standard for professional air conditioning system sizing. LOAD CALCULATION MODES: Cooling Mode - Calculate BTU/h cooling requirement for air conditioning Heating Mode - Calculate BTU/h heating requirement for furnace and heat pump sizing Automatic Tonnage Conversion - Get AC tonnage (0.5 to 5+ tons) from load results CFM Requirement - See required airflow for proper system balance ROOM PARAMETERS: Room Dimensions - Enter length, width, and ceiling height Insulation Levels - Poor, Average, Good, or Excellent with correction factors Window Types - Single Pane, Double Pane, Triple Pane, Low-E glass options Climate Zones - 5 zones from Hot to Cold with design temperatures Occupant Load - Account for sensible heat from building occupants COMPONENT BREAKDOWN: See loads from walls (exterior and interior) Window gain/loss calculations Ceiling and roof heat gain Floor infiltration and air leakage Occupant sensible heat contribution Component-by-component analysis for system design OPTIONAL PRO UPGRADE — $2.99 ONE-TIME IN-APP PURCHASE The following features require a separate one-time in-app purchase. They are not required to use the calculator: • Unlimited saved calculation history • PDF export of results • Dark theme • Ad-free experience WHY HVAC PROS USE THIS CALCULATOR: Faster Manual J estimates than spreadsheets or online calculators Accurate BTU sizing prevents oversized/undersized systems Reduces callbacks from incorrect system selection Quick cooling load checks on service calls ASHRAE-compliant Manual J methodology for commercial work Improves customer confidence with detailed technical reports PERFECT FOR: HVAC design engineers sizing air conditioning systems HVAC field technicians quick-checking load requirements AC contractors preparing accurate equipment bids HVAC apprentices learning Manual J methodology Building maintenance engineers planning replacements Residential and commercial HVAC system sizing Energy auditors estimating cooling needs Based on simplified ACCA Manual J design methodology. Part of HVACTools Suite - the professional HVAC technician app for field calculations, refrigeration diagnostics, and air conditioning system design.