Which PS2 BIOS to Use
Match the BIOS to your game's region. If you play US or English games, use the USA (NTSC-U) BIOS. If you only ever keep one file, make it the USA one.
The PS2 was region locked in hardware. The BIOS region tells your emulator how to run each game. Pick the wrong region and a game can crash, show a black screen, or run at the wrong speed. So the choice is simpler than most guides make it sound. You match, and you move on.
Pick your BIOS by region first
Region is the one thing that decides compatibility. Model and version matter far less.
PS2 games ship under two broadcast standards. NTSC runs at 60 Hz and covers North America and Japan. PAL runs at 50 Hz and covers Europe, the UK, and Australia. That single difference is why a mismatched BIOS causes speed and timing problems. Here is the model to use for each region.
USA BIOS (NTSC-U)
Best single choice for US, Canadian, and most English games. Use SCPH-39001 (fat) or SCPH-70012 (slim). Both run at 60 Hz and cover the large majority of the library. If your games are mostly English, this is the file you want. You can grab it on our PS2 BIOS USA page.
Japan BIOS (NTSC-J)
Needed for Japan-only and region-locked Japanese titles. Use SCPH-10000 or SCPH-18000. One note that matters: SCPH-10000 was the first PS2 BIOS ever made and has weaker support for later games. So SCPH-18000 is the safer Japanese pick unless you play very early Japanese releases.
Europe and Australia BIOS (PAL)
Use this for UK, European, and Australian games. Use SCPH-50003 (fat) or a slim PAL unit such as SCPH-70004 or SCPH-90004. PAL runs at 50 Hz, and many PAL games run about 17 percent slower than their US versions. If a game exists in both regions, the US version usually plays better.
China BIOS (NTSC-C)
Only for China-region titles. Use the SCPH-70000 China variant. Most players never need this one, so skip it unless you own specific Chinese-region games.
How to find your game's region
Check the game's serial code. The prefix tells you the region at a glance, and it decides which BIOS you match.
Every PS2 game has a serial like SLUS-20946. The letters at the front are the giveaway. SLUS and SCUS mean USA (NTSC-U). SLES and SCES mean Europe (PAL). SLPS, SLPM, and SCPS mean Japan (NTSC-J). You will find this serial on the disc, on the case spine, or inside an ISO's file details. Once you know the region, use the matching BIOS from the sections above. If the serial is hard to read, the case usually prints the region too, such as a PAL mark or an NTSC U/C label.
Fat or slim: does it matter?
For emulation, barely. Region match matters far more than fat versus slim.
Slim consoles (SCPH-70000 and above) use a later hardware revision than the fat models. Both run cleanly in emulators. Choose your region first, then use whichever model you have for that region. Do not spend time hunting a specific chassis.
Do version numbers matter?
Not the way most guides claim. For emulation, region decides whether a game runs. A higher version number is not automatically better.
You will often see a firmware version label attached to a model. These labels are inconsistent across sources, and the gap between them is small for most players. So pick your BIOS by region and model, not by chasing a version. If an early title misbehaves, try a different model from the same region before you worry about a version at all.
Which PS2 BIOS to use for PCSX2
Use the USA BIOS (SCPH-39001 or SCPH-70012) as your default on desktop. Switch to the matching region only if your game is Japanese or PAL.
PCSX2 lets you keep several BIOS files in one folder and pick the one you want. Once you have the file, our install guide shows exactly where it goes on Windows, macOS, and Linux. You can also see the desktop-specific details on the PS2 BIOS for PCSX2 page.
Which PS2 BIOS to use on Android
Same rule. The USA BIOS works for most libraries on NetherSX2, AetherSX2, and PCSX2's Android build.
One thing to know: AetherSX2 is no longer updated, and NetherSX2 is the maintained fork today. Both read the same BIOS file, so your region choice does not change. The full Android walkthrough is on the PS2 BIOS for Android page. If you use Play! instead, you need no BIOS at all, because Play! has one built in. Our best PS2 emulator guide covers which apps need a BIOS and which do not.
Can you use one BIOS for everything?
Often yes, especially for a single-region library. A USA BIOS runs most games without trouble.
Region-locked titles are the exception. They need a matching regional BIOS to boot correctly. The easy fix is to keep several BIOS files in the same bios folder and switch between them in your emulator settings, with no reinstall. If your library spans regions, keep all of them on hand.
Signs you picked the wrong region
The usual signs are a black screen on boot, sound that plays too fast or too slow, or a game that refuses to save.
A region mismatch confuses the video timing, so you get a black screen or the wrong speed. Some region-locked titles will not boot at all. If you see any of these, switch to the BIOS that matches the game's region and load it again. If the trouble stays after you match the region, it is usually a different problem, and our BIOS errors and fixes page covers the rest.
Make sure your BIOS file is the right one
A correct BIOS file matches a known-good checksum. If it does not match, it is incomplete or has been tampered with.
Check the file's SHA-256 or MD5 against a known-good value before you trust it. Our PS2 BIOS files explained page shows how, and every file we host is matched this way. The only method that is legal everywhere is dumping the BIOS from a console you own, which our dump guide walks through step by step.
Quick reference
| Your situation | Use this BIOS |
|---|---|
| US or English games | USA (NTSC-U), SCPH-39001 or SCPH-70012 |
| Not sure, want the widest compatibility | USA (NTSC-U), the safest default |
| Japanese exclusives | Japan (NTSC-J), SCPH-18000 |
| UK, European, or Australian games | PAL, SCPH-50003 or a slim PAL unit |
| China-region games | NTSC-C, SCPH-70000 China variant |
| Mixed-region library | Keep all regions and switch as needed |
Ready to set it up? Download the region you need on the PS2 BIOS download hub, then follow the step-by-step install guide. If a game still will not boot, our BIOS not found fix page sorts out the common causes.