Calculate an Air Conditioner Circuit Breaker and Convert Cubic Feet to Tons for Air Conditioning

Because air conditioners only advertise the type of voltage and wattage they require, you might run into some confusion when thinking about what kind of strength your circuit breaker should have. Since circuit breakers measure their capacity in amps, you must do a bit of math before coming to a suitable conclusion. Getting an undersized circuit breaker will cause your air conditioner to trip the breaker every time it demands too much current from it.

How to Calculate an Air Conditioner Circuit Breaker

Check your air conditioners wattage in its specification sheet. Write down the maximum wattage it uses. If it doesnt mention wattage, check the SEER rating of your air conditioner and the cooling BTU number.

Make sure you use the input BTU and not the output BTU, if both are listed. Divide the input BTU of your air conditioner by the SEER rating to get the amount of watts it requires, and write that down. Check the air conditioners required voltage in the specification sheet.

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If you dont see a voltage requirement, check the plug on the air conditioner. If you see a normal household plug on it with three straight prongs, assume 120 V of power requirement. If you see a plug with two diagonal prongs and one straight prong under it, assume 240 V of power requirement.

Divide the wattage number from Step 1 by the voltage number from Step This gives you the amount of amps you need your circuit breaker to resist.

How to Convert Cubic Feet to Tons for Air Conditioning

Check to make sure the cubic foot measurement of your room or home is correct. Find the length, width and height of a room, and multiply those numbers together. For more than one room, find the measurements of each room and multiply the numbers individually.

Add the cubic feet measurements from each room together to find the number for your entire home. Multiply your cubic foot measurement by 1,027 to convert to British thermal units. For example, a 50-cubic foot room multiplied by 1,027 equals 51,350 British thermal units.

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Divide your British thermal units number by 12,000 to convert to tons. For example, a room that requires 513,500 British thermal units per hour to cool would require a 4. 3 ton air conditioning system.


There is a direct relationship between the volume of a room measured in cubic feet and the tonnage size of an air conditioner unit that should be used with that room. Finding the cubic feet of a room is as simple as multiplying its length, width and height. Converting that number over to the appropriate amount of tons for AC installation can then be accomplished with — what else — more simple math.

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