The term “Power Supply Size” encompasses two important aspects: the wattage capacity of the power supply and the physical dimensions of the PSU. In this article, we will look at various PSU sizes based on their physical measurements.
Based on the size & shape, the Power Supply has different form factors such as (ATX, SFX, TFX, Flex ATX, etc). Each of these PSUs is different in terms of height, width, and depth.
Below, I have explained the different sizes of these Power Supplies and what Power Supply size will fit inside your PC cabinet. So, keep reading this article till the end.
Power Supply Standard Sizes
To explain to you the standard sizes of the Power Supplies here, I have made a table. In this table, W stands for the width, H stands for the height, and D stands for depth-
| PSU Standard | Sizes |
| ATX PS/2 | 150mm(W) x 86mm(H) x 140mm (D) |
| ATX PS/3 | 150mm(W) x 86mm(H) x 100mm (D) |
| ATX Large | 150mm(W) x 86mm(H) x 180mm (D) |
| ATX- EPS | 150mm(W) x 86mm(H) x 230mm (D) |
| SFX | 125mm(W) x 63.5mm(H) x 100mm (D) |
| TFX | 85mm(W) x 64mm(H) x 175mm (D) |
| LFX | 62mm(W) x 72mm(H) x 210mm (D |
Now, we’ll take a closer look at the actual sizes of these power supplies and see which types of PC cases they work well with.
- ATX PS/2: The size of this PSU is 150mm(W) x 86mm(H) x 140mm(D), and this PSU is compatible with most standard ATX computer cases. Moreover, this PSU is also suitable for mid-tower and full-tower cases with regular dimensions.
- ATX PS/3: The size of this PSU is 150mm(W) x 86mm(H) x 100mm(D), and it is almost similar to ATX PS/2 but shorter in depth. This PSU is compatible with compact mid-tower cases and can often be used in smaller ATX cases with limited space.
- ATX Large: The size of this PSU is 150mm(W) x 86mm(H) x 100mm(D), and it is longer than the previous two PSUs and is compatible with the larger ATX PC Cases.
- ATX- EPS: The size of this PSU is 150mm(W) x 86mm(H) x 230mm(D), and it is the longer PSU compared to the other ATX PSU. These PSUs are mostly compatible with the server PC Cases.
- SFX: The size of this PSU is 125mm(W) x 63.5mm(H) x 100mm(D), and it is a compact size PSU. This PSU is only suitable for mini-ITX or micro-ATX cases with limited component space.
- TFX: The size of this Power Supply is 85mm(W) x 64mm(H) x 175mm(D), and it is designed for slim and low-profile PC cases. This type of PSU is mostly used in small office PCs or home theater PC setups.
- LFX: The size of this PSU is 62mm(W) x 72mm(H) x 210mm(D), and it has an extremely compact size. It is compatible with specialized cases where space is at a premium, such as some compact embedded systems.
ATX Power Supplies Have Different Dimensions
As explained above, there are different ATX PSUs available, and the height and width of these different ATX PSUs are almost the same; the only difference is in their depth.
For instance, the ATX PS/2 & ATX PS/3 have the same height and width (150mm(W) x 86mm(H)), but the depth of the ATX PS/2 PSU is 140mm, and the depth of ATX PS/3 is 100mm.
Besides considering the height and width of the PSU, depth is also crucial. Choosing a PSU with the wrong width might not fit well in your PC case.
However, in the market, mostly you will get two types of Power Supplies ATX and SFX. Here, the ATX refers to the (ATX PS/2), the most common and widely used Power Supply size. This ATX PSU is also known as the standard Power supply size.
What Power Supply Size Do I Need?
What Power Supply size (ATX, SFX, TFX) you need depends on what kind of PC you are trying to build and what kind of PSU your cabinet will support.
There are different types of PC cases, such as (Full Tower, Mid Tower, Mini Tower, Micro ATX, Mini ITX, etc). Each type of PC Case has different spaces for the Power Supply unit.
For your convenience, here I’ve created a table that will assist you in figuring out which type of PSU fits into which type of PC Case-
| PC Case Types | Compatible PSU Types |
| Full Tower | ATX |
| Mid Tower | ATX |
| Mini Tower | ATX, SFX |
| Micro ATX | ATX, SFX |
| Mini ITX | SFX, TFX |
Some Full Tower and Mid-Tower PC Cases include adapters or brackets for the SFX PSUs, and you can put your SFX PSU inside these cases.
Power Supply also needs to be compatible with other PC components; read these articles to know- PSU Compatibility with CPU and PSU Compatibility with GPU.
Additional Tips For Beginner’s PC Builders
If you’re building a PC for the first time, then you might be confused about what PSU size you should pick for your system. Here, I will give you some tips that will help you to select the proper PSU size-
- Check The PC Case Specs: If you have already selected your PC Case, then you need to check the specifications of your cabinet. The specification sheets will clearly mention what size PSU (ATX, SFX, TFX) will be compatible with this case.
- Measure the Available Space: If the specification sheets doesnt tell you what PSU size will be compatible, then measure the available space for the power supply. Pay attention to the width, depth, and height. This will give you an idea of how much room you have to work with.
- Check PSU Dimensions: If you select the Power Supply, then note down its dimensions, including its width, depth, and height. This information is usually available on the PSU manufacturer’s website or on the packaging. This info will help you to find a perfect PC Case.
- Use PCPartsPicker Website: This is likely the best way to check if the PC case and PSU sizes match. Go to PCPartsPicker.com, pick your PC case, then choose a PSU. It will show you if the PSU will work well with the case.
