HVAC Heating & Cooling BTU Calculator

Calculate room cooling & heating BTUs, AC tonnage, ductless mini-split sizing, and CFM airflow.

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HVAC / Room Heating & Cooling BTUs Calculator

Accurately size room air conditioners, ductless mini-splits, heat pumps, and central HVAC systems. Calculates BTU/hr, tonnage, CFM airflow, and annual cooling electrical costs based on climate zone, insulation, ceiling heights, and solar exposure.

1. Climate Zone & Building Envelope

Select your geographic climate zone and building insulation quality.

Measurement Unit

Geographic Climate Zone

Balanced 4 seasons, moderate summer peaks and cold winter periods.

Insulation & Home Age

Standard 2x4 fiberglass batt insulated walls and insulated double-pane glass.

Sunlight & Shading Exposure

Heavily shaded spaces need ~10% less cooling; direct south/west glass needs +10%.

2. Room Dimensions & Internal Heat Sources

Add individual rooms or open floor plan zones with ceiling heights, window solar loads, and appliances.

Rooms / Zones

Define the dimensions and heat loads for each room.

Room Name

Length (feet)

Width (feet)

Ceiling Height (ft)

Regular Occupants

+600 BTU/person over 2

Sunny Windows

+800 BTU/window

Is Kitchen (+4k BTU)

3. System Type, SEER2 Efficiency & Electricity Rate

Estimate annual electrical cooling operational cost based on SEER2 rating and local utility rates.

HVAC System Style

SEER2 Efficiency Rating

Standard: 14-16; High-efficiency Mini-Split: 18-24 SEER2

Electricity Rate ($/kWh)

US average ≈ $0.16/kWh

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