We usually choose an air conditioner based on BTU and room size. However, when we’re trying to estimate energy costs, it’s very useful to know how many watts our particular air conditioner use.
How many watts does an air conditioner use?
Air conditioner wattage is not the easiest information to come by.
Not knowing how many watts does a 5,000 BTU air conditioner use is actually pretty normal. As far as lowering the air temperature is concerned, you only need to know that it has 5,000 BTU and is correctly sized for your room/space. Most homeowners don’t actually know their air conditioner wattage.
An average 5,000 BTU air conditioner uses 500W of energy running at full capacity. Below we also specify an estimate of how many watts does a window, portable, and mini-split AC use. We are talking about air conditioner power rating in watts.
You can estimate how many watts does an air conditioner with known capacity (BTU) use pretty well with this AC wattage calculator:
There are 3 ways how to check how many watts does your air conditioner use:
- Check the specification sheet for Watts. You’ll find the power or wattage (in Watts) in the same section as amperage (in Ampers) and voltage (in Volts).
- Check the specification sheet for Ampers and Volts. The power is simply calculated by multiplying the number of Ampers with the number of Volts (something like 10A * 120V = 1,200W).
- Use BTU and EER rating to calculate how much power does your air conditioner use. You can divide the BTU by EER rating (something like 5,000 BTU / 10 EER = 500W).
Below you find a table of how many watts do different air conditioners – from 5,000 BTU to 18,000 BTU – use.
A rule of thumb to estimate how many watts of energy different air conditioners use is to take the BTU number and divide it by 10. That’s how you can easily estimate that 5,000 BTU AC units use 500W of energy.
How Much Power Do Air Conditioners Use?
The relationship between BTU and the power (in watts) of an air conditioner is determined by the energy-efficiency EER rating. A good EER rating, for example, is 10. That means that 500W will give us 5,000 BTU of cooling effect. If an air conditioner had a higher EER rating (12, for example), the 500W would give us 6,000 BTU of cooling effect.
In the table above, we’ll assume that the EER rating of all AC units is between 8 and 12. That’s why you’ll see a range for the wattage of air conditioners with the same BTU number:
|How many watts does a 5000 BTU AC use?||417 – 625 W|
|How many watts does a 6000 BTU AC use? (1/2 ton)||500 – 750 W|
|How many watts does an 8000 BTU AC use?||667 – 1000 W|
|How many watts does a 10000 BTU AC use?||833 – 1250 W|
|How many watts does a 12000 BTU AC use? (1 ton AC wattage)||1000 – 1500 W|
|How many watts does a 15000 BTU AC use?||1250 – 1875 W|
|How many watts does an 18000 BTU AC use? (1.5 ton AC wattage)||1500 – 2250 W|
Example 1: What is 1 ton AC wattage? A 1-ton air conditioner (12,000 BTU) with a 10 EER rating has a 1,200 wattage.
Example 2: What is 1.5 ton AC wattage? A 1-ton air conditioner (18,000 BTU) with a 10 EER rating has a 1,800 wattage.
You can pretty much figure out what is any AC wattage using EER. Here is the AC wattage formula based on EER rating:
AC Wattage = AC Capacity (in BTU) / EER Rating
Let’s say you want to figure out the AC wattage of a 2-ton unit with a 12 EER rating. Here is the wattage calculation:
2 ton AC Wattage = 24,000 BTU / 12 = 2,000 W
That means that a 2-ton AC has a 2,000W wattage.
As you can see from the table above, a 12,000 BTU air conditioner can use 1500W (8 EER rating) or 1000W (12 EER rating). In short, having a high energy efficiency air conditioner with a high EER rating pays off. We have gathered the most energy-efficient portable AC units here.
How Many Watts Does A Window AC Use? (500 – 2,500W)
In general, the EER rating of window AC units ranges from 8 EER (energy inefficient) to 12 EER (energy efficient).
Based on these two factors – cooling output (BTUs) and energy rating (EER) – we can calculate how many watts does a window AC use. For that, we use this EER equation:
EER Rating = BTU Output / Max. Wattage
Let’s express ‘Max. Wattage’ in this way:
Max. Wattage = BTU Output / EER Rating
If we presume that an average EER rating of a window AC unit is 10, we can easily calculate window AC wattage with a certain BTU cooling output. Window AC wattage ranges from 500 watts to 2,500 watts.
For example, a 14,000 BTU window air conditioner with a 10 EER rating draws:
Max. Wattage = 14,000 BTU / 10 EER = 1,400 Watts
Such a window air conditioner uses 1,400 watts. Based on 10 EER rating, we have calculated the wattages of both small and big window air conditioners with 5,000 BTU to 25,000 BTU cooling outputs:
|Window AC Unit Capacity (in BTU):||Power Draw (in Watts):|
|5,000 BTU||500 watts|
|6,000 BTU||600 watts|
|7,000 BTU||700 watts|
|8,000 BTU||800 watts|
|9,000 BTU||900 watts|
|10,000 BTU||1,000 watts|
|11,000 BTU||1,100 watts|
|12,000 BTU||1,200 watts|
|13,000 BTU||1,300 watts|
|14,000 BTU||1,400 watts|
|15,000 BTU||1,500 watts|
|16,000 BTU||1,600 watts|
|17,000 BTU||1,700 watts|
|18,000 BTU||1,800 watts|
|19,000 BTU||1,900 watts|
|20,000 BTU||2,000 watts|
|21,000 BTU||2,100 watts|
|22,000 BTU||2,200 watts|
|23,000 BTU||2,300 watts|
|24,000 BTU||2,400 watts|
|25,000 BTU||2,500 watts|
These are rough estimates of how many watts do window air conditioners use.
We can use the same principle to calculate how many watts do portable and mini-split air conditioners use:
How Many Watts Does A Portable AC Use? (940 – 1,650W)
Portable air conditioners use, on average, more watts than window AC units. That is because the average EER rating of a portable AC unit is 8.5; portable units will need, on average, about 15% more watts for the same output. This means that portable AC wattage ranges between 940 watts and 1,650 watts.
The cooling output of the portable air conditioners ranges from 8,000 BTU to 14,000 BTU.
Here is a table of how many watts do portable air conditioners use:
|Portable AC Unit Capacity (in BTU):||Power Draw (in Watts):|
|8,000 BTU||940 watts|
|9,000 BTU||1,060 watts|
|10,000 BTU||1,180 watts|
|11,000 BTU||1,300 watts|
|12,000 BTU||1,410 watts|
|13,000 BTU||1,530 watts|
|14,000 BTU||1,650 watts|
These are estimates of how many watts do portable air conditioners draw.
How Many Watts Do Mini Split Air Conditioners Use? (500 – 2,500W)
Mini-split air conditioners are more energy-efficient than the window and portable AC units and thus draw fewer watts and amps for the same cooling output. On average, the EER rating of mini-split AC units is about 12.
Mini-split AC units can be very small (9,000 BTU), mid-range (24,000 BTU), and we also have the big multi-zone units with up to 60,000 BTU (5-tons) of cooling output.
To answer how many watts does your mini split AC unit use, you can consult this table (with presumed 12 EER rating for all units):
|Mini-Split AC Unit Capacity (in BTU):||Power Draw (in Watts):|
|9,000 BTU (0.75 tons)||750 watts|
|12,000 BTU (1 ton)||1,000 watts|
|18,000 BTU (1.5 tons)||1,500 watts|
|24,000 BTU (2 tons)||2,000 watts|
|30,000 BTU (2.5 tons)||2,500 watts|
|36,000 BTU (3 tons)||3,000 watts|
|42,000 BTU (3.5 tons)||3,500 watts|
|48,000 BTU (4 tons)||4,000 watts|
|54,000 BTU (4.5 tons)||4,500 watts|
|60,000 BTU (5 tons)||5,000 watts|
Note about RV air conditioners and wattage: How many watts do RV air conditioners draw? An average 15,000 BTU RV air conditioner will require about 1,500 watts to run. However, it will need about 3,000 watts or even 3,500 watts start-up wattage.
When you figure out how many watts does an air conditioner draws, you can calculate how much it costs to run such an AC. That is, if you have a continuous source of electricity, which brings us to the next chapter:
Best Generators For Air Conditioners
If you don’t have a source of electricity readily available, you’ll most probably need a generator to create about:
- 500 W for 5,000 BTU AC unit. Here is a calculation of what size generator you need for a 5000 BTU air conditioner.
- 1,000 W for 10,000 BTU AC unit.
- 1,500 W for 15,000 BTU AC unit.
For bigger air conditioners (1-6 ton), you can check the calculation of what size generator do you need for a 5-ton air conditioner here.
We’ve received many questions about which generators are best for a certain capacity of an air conditioner. Here are some of the generators you can use:
- Jackery Portable Power Station Explorer 500W for small 5,000 BTU units.
- Jackery Portable Power Station Explorer 1000W for medium 10,000 BTU units.
- Honda EU2200i 2200W for larger 15,000 BTU to 20,000 BTU units.
All these generations will cover the basic wattage needed to power your air conditioner.
Cost Of Running A 1,000 W Air Conditioner (Estimate)
High wattage air conditioners cost more to run. For example, a 1000W AC unit spends 1 kilowatt-hour of electricity per hour. 1500W unit, for comparison, spends 1.5 kWh of electricity per hour.
Given that an average price of 1 kWh in the US is $0.1319, you can save quite a bit if you invest in an above-average energy-efficient air conditioner.
The average cost of running a 1000W air conditioner is thus $0.1319 per hour. That translates to about $1 for air conditioning if you run such a unit for 8 hours a day.
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