Before buying an air conditioner, you have to make the AC tonnage calculation. Not sizing an AC unit properly can cause $100s in wasted unit or electricity costs.

According to the DOE, “…an air conditioner generally needs 20 BTU for each square foot of living space.” We need to convert BTU to tonnage. 1 ton equals to 12,000 BTU. That means that, on average, we will need **0.0016 tons per square foot**.

To properly get the tonnage of the AC you need, you can use the AC tonnage calculator here:

For example, a standard 1,500 sq ft house would need a 2.5-ton air conditioner. To help us out here is a quick table showing how many tons (and BTU) air conditioners we need for certain square footage:

## Tonnage Table

Area (Square Feet): | BTU | Tonnage |
---|---|---|

600 sq ft | 12,000 BTU | 1 Ton |

900 sq ft | 18,000 BTU | 1.5 Tons |

1,200 sq ft | 24,000 BTU | 2 Tons |

1,500 sq ft | 30,000 BTU | 2.5 Tons |

1,800 sq ft | 36,000 BTU | 3 Tons |

2,100 sq ft | 42,000 BTU | 3.5 Tons |

2,400 sq ft | 48,000 BTU | 4 Tons |

2,700 sq ft | 54,000 BTU | 4.5 Tons |

3,000 sq ft | 60,000 BTU | 5 Tons |

3,300 sq ft | 66,000 BTU | 5.5 Tons |

3,600 sq ft | 72,000 BTU | 6 Tons |

In short, you can use 0.0016 tonnage per sq ft.