Window, portable and RV air conditioners use 625 watts to 3,000 watts depending on their size in BTU/hour.

A 12,000 BTU window AC uses 1,250 to 1,500 watts.

A 14,000 BTU portable AC uses 1,400 to 1,750 watts.

An RV AC uses 1,350 to 1,800 watts depending on its size and efficiency.

This page includes:

**A conversion calculator**you can use to determine how many watts your AC uses. And if you want, you can divide watts by 1000 to know the kW, or kilowatts.**An air conditioner power consumption chart**for quick reference when you want to convert BTU to watts.**A chart showing what size generator is needed**to run a window, portable or RV air conditioner.

Content Navigation

## How Much Energy Does an AC Use?

Many of us use a small window AC or portable air conditioner to create a cool room in our home. Or you might use an AC and heating window unit – a heat pump – or a mini split system.

We all want to know: How much electricity do they consume? And how much is that costing to run the AC?

Other readers are concerned about power outages or running an AC off the grid, for example while camping in an RV, and want to confirm what is the right size generator to run an AC.

We need to know: What size generator do I need to run an AC of ____ BTUs?

The answers are here!

## Calculator – Convert BTU to Watts

This Pick HVAC conversion calculator has a built in formula for dividing the unit’s BTU/hr rating by the efficiency in EER to show the watts used by the AC.

It is pretty simple. Input the BTU rating and the EER efficiency rating. The number of watts the unit uses will automatically show.

The BTU and EER information should be found right on your air conditioner – usually on a sticker or metal label that includes the Model #, Serial #, Volts and more.

**BTU to Watts Calculator**

**How much electricity does a window AC use?**

Input the information into the calculator to get the results.

**Example 1: **Let’s say you have a 12,000 BTU AC with 8 EER. When you enter that information, you’ll find that the window AC uses 1500 watts to run. Starting watts are slightly higher.

**Watts to kW conversion factor: **If your energy bill shows the cost per kilowatt, or kW, simply divide the number of watts the AC uses by 1,000 to determine kilowatts. This is because 1,000 watts = 1 kilowatt, or kW.

## Table – How Many Watts Does an AC Use?

The air conditioner power consumption chart shows common sizes for a portable air conditioner, mini split AC, RV AC (13,500 BTU is most common) and a large or small window AC.

### How many watts does a 5,000 - 24,000 BTU air conditioner use

Air Conditioner Capacity (BTU) | Power (Watts) |
---|---|

5,000 BTU | 625 Watts |

6,000 BTU | 750 Watts |

8,000 BTU | 1,000 Watts |

9,000 BTU | 1,125 Watts |

10,000 BTU | 1,250 Watts |

12,000 BTU | 1,500 Watts |

13,000 BTU | 1,625 Watts |

14,000 BTU | 1,750 Watts |

15,000 BTU | 1,875 Watts |

18,000 BTU | 2,250 Watts |

24,000 BTU | 3,000 Watts |

** Based on 8 EER*

If your AC has a higher EER, it will use fewer watts. Use the Calculator above for precision results.

**How much electricity does a portable ac use?**

Most portable ACs are 14,000 BTU. Using the chart, find 14,000 in the left-hand BTU column. Scan to the right, to the Power (Watts) column, and you’ll see that a 14,000 BTU AC uses 1,750 watts.

The table is based on an 8 EER AC. If your air conditioner has a different energy efficiency, use the BTU to Watts Conversion Calculator above for precise results.

**How much does it cost to run an AC?**

Use the calculator or the table to determine how many watts your unit uses per hour. Consider how many hours you run the AC, and multiply the watts times the number of hours to get total watts used.

Then divide that number by 1,000 to get the number of kilowatts, or kW, you use. Finally, check your energy bill to see the cost of electricity per kilowatt hour to determine how expensive it is to operate your AC.

**What’s a good size for a low wattage air conditioner?**

A room AC between 5,000 and 10,000 BTUs uses less power than most hair dryers, so those are good choices for a low wattage AC.

## Table – What Size Generator to Run an AC?

That’s an important question to have answered if you have an RV air conditioner or want to install an AC in a location off the grid. Many homeowners in warm, stormy climates also want to know what size generator is needed to run a window or portable AC in a power outage.

### What Size Generator To Run A Window, Portable Or Rv Air Conditioner?

Air Conditioner Capacity (BTU) | Generator Size (Watts) |
---|---|

5,000 BTU | 2,000 Watts |

7,000 BTU | 2,100 Watts |

8,000 BTU | 2,200 Watts |

10,000 BTU | 2,500 Watts |

12,000 BTU | 2,800 Watts |

13,500 BTU | 3,000 Watts |

14,000 BTU | 3,100 Watts |

15,000 BTU | 3,500 Watts |

## FAQs

**What size generator to run 13,500 btu RV air conditioner?**

Find the answer using the table. Locate 13,500 in the AC Capacity (BTU) Column. Scanning to the right, you see that you’ll need 3,000 watts to run a 13,500 BTU AC – a 3,000 watt generator is the minimum requirement. Generators in that range provide more power to give an AC the starting watts it needs to get going.

**How big of a generator do I need to run a 5000 btu air conditioner?**

Using the table, you’ll see that a 5,000 BTU AC needs 2,000 watts of power.

Looking at it the other way, will a 2000 watt generator run a 5000 btu air conditioner? The answer is yes, but you might need a larger generator to provide the necessary starting watts. If you have concerns about whether a 2,000 watt generator has enough power for your needs, choose one with 3,000 watts. The extra cost will be minimal, and you’ll have all the juice you need with some to spare.

**Will a 3000 watt generator run a RV air conditioner?**

Most camper air conditioners are 13,500 or 15,000 BTU. A 3,000 watt generator will produce enough watts to run a 13,500 BTU AC. Generators are rated by their maximum watt production, called surge watts or starting watts.

**Tip: **You will be assured of reliable cooling with a 3,500 watt generator to power a 15,000 BTU RV air conditioner. It will have sufficient capacity to start and run the AC.