Calculators
- HVAC Load CalculatorWhole-house and room-by-room cooling and heating load calculator using square footage, climate zone, insulation, and occupancy.
- HVAC Tonnage CalculatorConvert cooling load (BTU/hr) or square footage to AC tonnage and recommended unit size.
- BTU CalculatorEstimate the BTU/hr needed to cool or heat a space based on size, climate, sun exposure, and ceiling height.
- CFM / Airflow CalculatorCalculate required CFM by tonnage, by ACH (air changes per hour), or from room volume and load.
- HVAC Duct Sizing CalculatorRecommended round and rectangular duct dimensions for a target CFM and friction loss.
- Complete HVAC System SizingEnd-to-end sizing: cooling load, heating load, tonnage, CFM, and duct size in one calculator.
- Heating Load CalculatorCalculate heating BTU/hr from indoor/outdoor design temperatures, envelope U-values, and infiltration.
- Manual J Calculator (Simplified)Simplified Manual J style room-by-room load calculator with sensible, latent, and total loads.
- Commercial HVAC Load CalculatorCommercial HVAC load with occupancy loads, equipment heat gain, lighting, ASHRAE 62.1 ventilation, and zone-by-zone distribution.
- Heat Pump Sizing CalculatorFind the right heat pump size in BTU and tons, with balance point and cold-climate capacity adjustments.
- AC Size CalculatorFind the right central AC size in tons and BTU/hr based on square footage, climate, and insulation.
- Furnace Size CalculatorCalculate required furnace BTU/hr by home size, climate zone, and insulation, including AFUE input sizing.
Guides
- What Is HVAC Load Calculation?A plain-English explanation of what an HVAC load calculation is and why it decides the size of every system.
- How to Calculate HVAC Load, Step by StepThe exact steps, inputs, and formulas to calculate heating and cooling load for a home.
- How to Measure Your Home for HVAC SizingA measuring checklist that gets you accurate inputs before you run a load calculation.
- HVAC Load Calculation Example: A Worked WalkthroughFollow a complete load calculation for a real home, number by number, to a final tonnage.
- The HVAC Load Calculation Formula, ExplainedThe core load formulas — sensible, latent, conduction, and infiltration — with what each term means.