Switch between cooling load, heating load, water heating, BTU conversions, multi-room planning, and appliance heat gain.
Uses a rule-of-thumb method with adjustments for sun, insulation, people, windows, and extra heat sources.
Required Cooling
Recommended AC Size
Summary
This heating estimate uses a BTU per square foot rule-of-thumb adjusted for climate, insulation, ceiling height, and temperature rise.
Required Heating
Estimated Furnace/Heater Size
Summary
Minutes
BTU/hr is based on 1 gallon of water needing about 8.33 BTU to rise 1°F. Temperature rise is converted from °C to °F.
Total Energy (BTU)
Required BTU/hr
Equivalent kW
Converts between BTU/hr, kW, and refrigeration tons using 1 kW ≈ 3412.14 BTU/hr and 1 ton = 12000 BTU/hr.
BTU/hr
kW
Tons
Enter up to 5 rooms. Leave area at 0 to ignore a room.
Total Cooling BTU
Recommended Total AC Size
Per-Room Summary
People and electrical devices add internal heat gain. This tool estimates total BTU/hr added to the cooling load.
Total Heat Gain (BTU/hr)
Equivalent Cooling Capacity
Breakdown
BTU Calculator – Cooling, Heating And Energy Explained
This BTU Calculator helps you estimate how much cooling or heating capacity you need, how much energy is required
to heat water, and how different appliances add to your overall cooling load. It also provides quick conversions
between BTU/hr, kW, and refrigeration tons.
Cooling Load
The cooling tab uses room size in combination with sun exposure, insulation, climate, occupancy, and windows to
approximate the required BTU/hr. The result is converted into tons of refrigeration to help you size an air
conditioner or multi-split system.
Heating Load And Water Heating
The heating tab uses a rule-of-thumb BTU per square foot method adjusted for climate severity, insulation quality,
ceiling height, and desired temperature rise. The water heating tab uses the heat capacity of water to calculate
total BTU and BTU/hr required to reach a target temperature within a chosen time.
Conversions, Multi-Room Planning And Appliances
The conversion tab quickly switches between BTU/hr, kW, and tons. The multi-room planner aggregates cooling needs
for up to five rooms. The appliance load tab estimates internal gains from people, lighting, electronics, and
other devices so you can fine-tune your cooling capacity.
