Standard outlets can handle quite a lot of watts before catching on fire. Of course, nobody really likes to watch an outlet catching on fire. That’s why we are going to check how much wattage can a wall outlet handle.
Below, we will illustrate how to calculate the max wattage for all receptacles. Standard outlets can handle anywhere from 1,320W to 5,150W (110V 15A to 220V 30A). We are going to show 3 examples, namely how many watts can a 15 amp, 20 amp, and 30 amp breaker handle. This plays a key role in determining how many watts can a standard outlet handle.
Note: To make things easier, you will also find an Outlet Wattage Calculator; you simply insert circuit size and voltage to get the max. outlet wattage. At the end, you will also find a summarized Outlet Wattage Chart detailing how many watts can 15A, 20A, and 30A circuit outlets handle on 110-volt, 115-volt, 120-volt, 220-volt, 230-volt, and 240-volt voltages.
Let’s first start by looking at the only two factors that determine how many watts can one outlet handle. These are:
- Breaker size (+ NEC 80% rule). In the US, standard residential breaker sizes are 15 amps, 20 amps, and 30 amps. This tells us how many amps can an outlet draw. We have to be careful, however. We can load a breaker to 80% of its amp rating (Example: We can put only 12 amps on a 15A circuit). This is known as the National Electric Code 80% rule or NEC 80% rule for short (explained in the NEC Article 210.21(B)(2)). It is a basic safety measure, preventing your receptacle from catching fire.
- Voltage. In standard outlets, we usually have 110V or 120V voltage. Further on, we also make calculations on how many wats can a 115V, 230V, and 240V outlets handle.
To calculate max. wattage for any outlet, we use this basic electric power equation:
Outlet Wattage = Max. Allowable Amps × Voltage
We get the ‘Max. Allowable Amps’ from breaker size. It’s vital we account for NEC 80% rule here. The ‘Voltage’ is pretty self-explanatory.
Here’s a quick example before we proceed: How many watts can a 110V outlet handle on a 15 amp breaker?
Well, a 15 amp breaker has a 15A amp rating. After applying NEC 80% rule, we see that putting an outlet on such a breaker can draw at most 12 amps (since 80% of 15A is 12A). We also know that the voltage is 110V. Here is what this calculation looks like:
110V 15A Outlet Wattage = 12 Amps × 110 V = 1,320 Watts
Let’s first show you how to calculate the wattage for any receptacle by hand. We will proceed to the calculator that does this calculation automatically and a summarized table where you can just check the breaker size and voltage, and get the wattage of your outlet:
How Many Watts Can A 15 Amp, 20 Amp, And 30 Amp Breaker Handle? (3 Examples)
In that equation above, we obviously know the voltage. What we don’t know is the maximum allowable amps for an outlet. We have to calculate that based on the breaker size and by applying the NEC 80% rule.
Let’s take a 20 amp breaker as an example. If we can determine how many amps can such a breaker provide to the outlet, we can (by also known the voltage) calculate how many watts can an outlet on a 20 amp circuit handle.
We know that we have 20A rated amps since this is a 20 amp breaker. Here is how we apply the NEC 80% rule:
Max. Allowable Amps (20A) = 20 Amps × 0.8 = 16 Amps
This means an outlet on a 20 amp breaker can draw 16 amps (or less). To calculate the wattage of such an outlet, we now only multiply the 16 amps by the voltage.
Here are the calculated max. wattages of 110V outlets on 15A, 20A, and 30A residential circuits:
- On 15A 110V, we have max. allowable outlet amps of 12A. Therefore a 110V outlet on 15A can provide 1,320 watts of power.
- On 20A 110V, we have max. allowable outlet amps of 16A. Therefore a 110V outlet on 15A can provide 1,760 watts of power.
- On 30A 110V, we have max. allowable outlet amps of 24A. Therefore a 110V outlet on 15A can provide 2,640 watts of power.
For comparison, if we were using 220V voltage, the max. receptacle wattages would be 2,640W, 3,520W, and 5,280W, respectively for 15A, 20A, and 30A circuits.
You will find all these 110V outlet, 120V outlet, and 220V outlet wattages in the chart below.
Using this calculator you can determine the outlet wattage by yourself:
Outlet Wattage Calculator
Just insert the breaker size and voltage, and the calculator will automatically calculate how many watts such an outlet can handle:
This calculator is quite easy to use.
Let’s say you have a 15A standard breaker and 115V voltage. How much power can such an outlet put out? Just slide the upper slider to ’15’ and the lower slider to ‘115’ and you get that such a 115V outlet can produce 1,380 watts.
To make things even simpler, you can consult the following chart that tells you how many watts can standard outlets handle:
Outlet Wattage Chart
|Voltage (Volts):||Breaker Size (Amps):||Outlet Wattage (Watts):|
|110 Volts||15 Amps||1320 Watts|
|110 Volts||20 Amps||1760 Watts|
|110 Volts||30 Amps||2640 Watts|
|115 Volts||15 Amps||1380 Watts|
|115 Volts||20 Amps||1840 Watts|
|115 Volts||30 Amps||2760 Watts|
|120 Volts||15 Amps||1440 Watts|
|120 Volts||20 Amps||1920 Watts|
|120 Volts||30 Amps||2880 Watts|
|220 Volts||15 Amps||2640 Watts|
|220 Volts||20 Amps||3520 Watts|
|220 Volts||30 Amps||5280 Watts|
|230 Volts||15 Amps||2760 Watts|
|230 Volts||20 Amps||3680 Watts|
|230 Volts||30 Amps||5520 Watts|
|240 Volts||15 Amps||2880 Watts|
|240 Volts||20 Amps||3840 Watts|
|240 Volts||30 Amps||5760 Watts|
With this chart, you can simply look at what voltage you have and how many amps breaker you have, and get the outlet wattage.
Hopefully, the manual calculation, calculator, and this chart illustrate well how to go about determining how many watts you can get from a single receptacle. If you have any questions, you can use the comments below and we’ll try to help you out.