Size calculator

Checkmark’s air conditioner system size calculator.

This is Checkmark’s size calculator to help assess the size of mini-split air conditioner required.

Room size (in metres)


Heat sources
(normally in room)
(active PCs, TVs etc)

Please enter some data above.
Just numbers, not units such as 'm'.

In general, practical minimums of around 7000 BTUs (2 kW) apply to small rooms (40 m3) and 10000 BTUs (3 kW) for medium rooms (52m3).

Note that most mini-splits are more efficient at heating than cooling.

About this calculator

Checkmark’s calculator is based on common metrics:

  • 180 BTUs / m3 per hour
  • 356 BTUs per person per hour
  • 500 BTUs per PC, TV
  • Insulation applies a factor of plus or minus 20% for ‘poor’ and ‘good’.
  • Heat sources reduce the load for heating and increase it for cooling.

This calculator requires JavaScript.
Disclaimer: Calculators don't replace the need to have an assessment by an experienced air conditioning or heat pump professional.

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