Are All Power Supplies the Same Size? Power Supply Sizing Guide

Are all power supplies the same size? Welcome to Bravo Electro's comprehensive guide on power supply sizing. This is a question that many people ask when they are in the market for a new power supply. The truth is that power supplies come in different shapes and sizes, and it's important to choose the right one for your needs.

In this blog post, we'll dive deep into the question "what size power supply do I need?" and provide you with a power supply size guide to help you choose the right one. Let's begin.

Are All Power Supplies the Same Size?

Are all power supplies the same size? As stated above, power supplies come in different shapes and sizes. Power supply size guides are based on wattage ratings which indicate the amount of electrical power they can provide. Typically, power supplies range from 1W all the way up to 30,000W. The size of each power supply will correlate to its wattage rating, with higher wattage ratings requiring larger power supplies.

And the actual size itself is measured in a number of different ways, such as the physical footprint (the area it takes up), the height and length of the device, and the number of cables that come with it. 

For example, a phone power supply usually has a lower wattage rating, so it will be smaller in physical size and have fewer cables. On the other hand, high-performance gaming PC power supplies will have a much higher wattage rating and be larger in size, with more cables.

In addition to this, some power supplies are modular and can be built to fit your specific device needs. But what does modular mean on power supply? Modular power supplies are designed with removable cables that can be configured depending on your computer's needs. This allows for greater flexibility and customization of the power. This is usually done with higher-end gaming PCs that require more specialized parts and components.

Why Proper Power Supply Sizing is so Important

Now that you know the answer to "are all power supplies the same size?", let's talk about why it is so important to get the right size power supply.

What Happens if My Power Supply is Too Big?

If your power supply is too big, you may have some immediate benefits when it comes to the performance and longevity of your system. However, this can also lead to potential hazards due to the extra power being unused. Additionally, having a power supply that draws more than necessary can put a strain on your other internal components; creating excess heat and noise.

You should ensure that you are only using the wattage recommended for your device according to its manual or specifications outlined by the manufacturer in order to avoid any of these potential issues. 

Having an oversized PSU can also create additional stress on important components such as cooling systems and cables which could decrease their overall life expectancy as well.

Taking into account each component’s power consumption rating will help you pick the best-sized PSU for your system before facing any unwanted consequences from an overly large power supply.

What if My Power Supply Size is Too Small?

If your power supply size is too small, this can cause serious damage to your device components. A power supply that is not rated for the wattage needed by your computer will be unable to provide adequate power for all the components, which may leave some without enough voltage or amperage, resulting in irreparable damage.

Furthermore, using an inadequate power supply may also cause overheating of components and ultimately catastrophic failure if your system attempts to draw more watts than what the PSU can support. This could potentially damage other components as well. 

Bad power supply symptoms in this case could consist of low performance, odd behavior, or unexplained shutdowns. Therefore, it is important to make sure that you purchase a power supply with a suitable output that matches or exceeds the demands of all your current hardware.

So, What Size Power Supply Do I Need? Step-by-Step Power Supply Size Guide

Making sure your device has the right-sized power supply is important for keeping it running smoothly. To answer "what size power supply do I need?", read on for our guide to help you make the best choice.


Add up the wattage of all the components you will need to get a sense of the total power needed. It's a good idea to factor in an additional 20% cushion in case there are any sudden power needs. 

You can find out the wattage of each component from its manual or specifications. And when it comes to AC vs DC power supply, it's important to make sure the PSU can support both if necessary. Since house electrical AC or DC power is usually the same, you'll need to check with your manufacturer. Learn more through our guide that explains what is an AC DC power supply

Power Supply Voltage

Take into account the efficiency of the power supply when making your choice. Efficiency refers to the percentage of energy a power supply can convert into useful power. Higher efficiency means less wasted energy and cheaper electric bills. Aim for a minimum of 80 Plus Bronze certifications.


When it comes to power supplies, there is the option of a modular design. Modular power supplies make it easy to use only the cables you need, reducing cable mess and improving the airflow in your PC case. You can choose from fully modular, semi-modular, or non-modular power supplies. Fully modular ones offer more flexibility but usually come at a higher cost.

Other Factors to Consider Beyond Power Supply Sizing

While the above steps are important for getting the correct power supply size, there are lesser-known factors that are just as important to consider. You don't want to worry about having to troubleshoot power supply down the line.

Future Upgrades

When choosing a power supply, factor in any potential upgrades or additional components you may add in the future. A power supply with a higher wattage can handle whatever upgrades you may have and prevent you from needing to upgrade your power supply down the line. This could ultimately save you money and time.

Form Factor

When it comes to power supplies, you'll want to make sure the form factor is compatible with your case. Generally, standard ATX power supplies are supported in most cases. However, some may require a smaller form factor such as SFX or SFX-L. Be sure to check the specifications of your case before making a decision.

UL Listed vs UL Recognized

When you're shopping for a power supply, make sure it is UL listed or at least UL recognized. This will help ensure the safety of your power supply and guarantee that the product meets industry standards. Under Underwriters Laboratories, UL listed means the power supply has passed all safety tests, whereas UL recognized means it only meets minimum requirements.

Brand Reputation

When it comes to power supplies, choosing one from a reputable brand is key. Brands such as Meanwell, Cincon, Digital Power, and IPD have an established history of creating reliable and durable products that won't let you down. Bravo Electro only partners with the best of the best brands. How long power supplies last often has to do with the brand. 

Type of Power Supplies

When selecting a power supply, consider the type of power supply that is right for your application. Here are the three available.

  • Enclosed power supplies: Enclosed power supplies are the most popular type of power supply and offer protection from dust and other external factors. They come in various form factors, such as ATX, SFX, and TFX, making them suitable for a wide range of applications.
  • Open frame power supplies: Open frame power supplies are similar to enclosed power supplies but lack the casing that provides protection from external elements. The internal components of open frame power supplies are mounted onto a metal frame.
  • DIN rail power supplies: DIN rail power supplies are specifically designed to be mounted on a DIN rail, which is an industrial standard for mounting components. 

Want Help With Power Supply Sizing? Our Electrical Engineers are Here to Guide You Through the Process!

Selecting the right power supply for your application can be difficult, which is why Bravo Electro offers assistance from our highly trained electrical engineers. We are here to help you make the best choice in terms of power supply sizing, ensuring that you get the perfect product for your needs.

If you're looking for a 12 volt DC power supply, 24 volt DC power supply, or 48 volt DC power supply, our electrical engineers can help. They will expertly assess the wattage and amperage that are right for your application and consider efficiency, future upgrades, and more when making their recommendation. 

By taking into account all of these factors, our electrical engineers can help ensure that you select a power supply with the best performance specs now and in the future.

Wrapping Up Our Power Supply Size Guide

Ultimately, your power supply is the key to optimal performance and efficiency for your electronic equipment. Choosing the right one is clearly essential.

So who makes the best power supplies? At Bravo Electro, we have a comprehensive selection of power supplies, such as an AC DC power supply, to meet the varied needs of our customers. 

Our team of electrical engineers is knowledgeable and experienced. They can provide you with invaluable advice and assistance to help you pick the perfect power supply for your particular application.

So what's next? Check out our guides that explain what LED driver you need and how to choose AC DC converter.

Or better yet, contact us today and let us help you choose the right power supply!