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Sizing Calculator

Select the Right Capacity

This handy sizing calculator will help you select the right system on an efficient room-by-room basis. Always take in to account your climate, insulation, excessive glass and other relevant factors. Rooms with conditioned space above them require less cooling than rooms upstairs that have attic space above them. Always adjust for poor insulation, excessive or drafty windows, etc.


adjustment map
Choose Adjustment Factor:
Room Length:
Room Width:


For rooms below a conditioned space, apply an additional .7 factor to your final Btu outcome.

For example, if your Btu requirement via this calculator is 18,000 Btu's: 18,000 Btu's x .7 factor = 12,600 Btu's required. When in doubt, it is okay to go up a size or two. Unlike standard non-variable systems, The Mitsubishi INVERTER technology allows the system to adjust to the actual room requirements in both heating and cooling.

The Mitsubishi system will provide as little as 30% of its rated capacity when the demand is low so oversizing is no longer an issue. With standard central air conditioning and heating systems, you must carefully match the air delivery with the room requirements.

Ordinary central air conditioning systems are normally sized based on an outdoor temperature of 93 degrees fairenheit. When the outdoor temperature exceeds 93 degrees, the system struggles to keep up. When the temperature is significantly lower, the system can short-cycle, meaning it cools quickly without the proper run time for thorough dehumidification. Either way, this is a significant short-coming of non-variable-capacity central systems.

The advanced INVERTER-driven compressor at the heart of the Mitsubishi ductless air conditioners and heaters provides variable capacity control for the compressor, slowing the system to adjust to the specific room-by-room demands of the interior space as needed – not the hard start and stop of a traditional system in most homes. Call our Personal Advisors toll-free at 1-855-634-5588 with questions

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