Security Screwdriver Sizes for NES, SNES, N64 and Game Boy

Quick answer

Nintendo's cartridge-based systems — NES, SNES, N64 and the original Game Boy line — use 3.8mm game bits, so a single 3.8mm security screwdriver opens almost all of them. The Game Boy Advance, DS family and Wii use tri-wing screws, which need a separate tri-wing driver. Buy the 3.8mm first if you're working on cartridges or a Game Boy; add tri-wing only when you move to GBA-era hardware.

Why Nintendo used security screws in the first place

Nintendo didn't pick these screws to frustrate hobbyists — they were designed to keep consumers out of hardware that could be damaged by static or incorrect reassembly. The 3.8mm game bit is a six-lobed design that a standard Phillips or flathead can't grip, and the tri-wing uses three offset slots that strip easily if you force a small flathead into them. That's the practical reason to own the correct bit: a stripped security screw is far harder to remove than a seized Phillips screw, and on cartridge shells the plastic around the screw post cracks before the screw gives way.

Which bit opens which Nintendo system

The 3.8mm game bit covers the widest range of retro Nintendo hardware. It opens NES, SNES and N64 cartridge shells, the original Game Boy, Game Boy Color and Game Boy Pocket cartridge and console housings, and the screws on many N64 and SNES console cases. The tri-wing bit is the one you need for Game Boy Advance, GBA SP, DS Lite, DSi and Wii shells, plus the battery covers on some GBA and DS models. A few later systems mix both — for example, a GBA cartridge uses a tri-wing screw, while the console itself may use Phillips screws inside once you're past the shell.

• 3.8mm game bit: NES, SNES, N64, Game Boy, Game Boy Color, Game Boy Pocket cartridges and shells
• Tri-wing: Game Boy Advance, GBA SP, DS, DSi, Wii, and some battery covers
• Phillips #00 and #000: internal screws once the security shell is off
• Flathead: rarely needed on Nintendo hardware, but useful for prying clips gently

What to do when a screw won't budge

If the bit slips instead of biting, stop before you round the screw head. The two most common causes are a bit that's slightly too small and downward pressure that isn't firm enough. Press straight down with steady force and turn slowly — security screws need axial pressure to engage, not speed. On older cartridges, a previous owner may have already stripped the screw; in that case, a rubber band between the bit and screw head can add grip, or you can carefully notch the head with a rotary tool as a last resort. Never use a power driver on a security screw; the torque is too easy to overapply.

Do you need a full bit set or just one driver?

If you only plan to replace save batteries in Game Boy cartridges or open a single SNES, one 3.8mm driver is enough and costs less than a multi-bit kit. A full set makes sense if you're repairing across generations — GBA, DS and Wii all need tri-wing, and you'll want Phillips #00 and #000 for the internals. The tradeoff is that cheap multi-bit kits often have loose tolerances, and a wobbly 3.8mm bit is the fastest way to strip a game bit. A dedicated driver with a machined tip holds up better over repeated cartridge openings.

Size chart at a glance

Use this as a quick reference before you buy or start a repair. If a system isn't listed, it likely uses standard Phillips screws inside, but confirm before forcing anything.

• NES cartridge and console: 3.8mm game bit
• SNES cartridge and console: 3.8mm game bit
• N64 cartridge and console: 3.8mm game bit
• Game Boy, Game Boy Color, Game Boy Pocket: 3.8mm game bit
• Game Boy Advance and GBA SP: tri-wing
• Nintendo DS and DSi: tri-wing
• Wii console: tri-wing

Reader questions we hear most

Will a 3.8mm bit open a Game Boy Advance?

No. The GBA and GBA SP use tri-wing screws on the shell. You need a tri-wing driver for those, not a game bit. The 3.8mm bit stops at the Game Boy Color and earlier. Check the screw head shape before buying — six lobes means game bit, three slots means tri-wing.

Can I use a flathead screwdriver instead?

You can sometimes turn a tri-wing with a very small flathead, but it's a gamble. The blade tends to cam out and chew the screw head, and a stripped tri-wing is difficult to remove without drilling. On game bits, a flathead almost never works because the recess is too shallow. Buy the correct bit; it costs less than replacing a stripped shell.

Is 3.8mm the same as 4.5mm game bit?

No. 3.8mm is the size for NES, SNES, N64 and Game Boy hardware. 4.5mm game bits are used on some other consoles and are too large for Nintendo's cartridge screws — forcing one will damage the screw recess. Match the bit to the system; don't assume all game bits are interchangeable.

Do I need a torque screwdriver?

Not for these repairs. Security screws on retro Nintendo hardware are small and the plastic is old, so hand pressure and a slow turn are safer. A powered driver applies too much torque and is the fastest way to crack a cartridge post. Use a manual driver and let the bit do the work.

Tools that match these sizes

• 3.8mm Security Screwdriver NES SNES N64 and Game Boy: Opens cartridges using security screws for the NES, SNES, N64 and Game Boy games, and is useful for replacing save batteries in Game Boy titles such as Pokemon Yellow, Blue and Red. This is the single driver that covers the entire 3.8mm game bit range, so it handles most retro Nintendo cartridge work without a multi-bit kit.
• SNES Console Cleaner - Super Nintendo Cleaning Cartridge by 1UPcard™: A console cleaner cartridge that cleans and polishes the pin connector inside an N64, intended for use before inserting games when the connector is dirty, grimy or corroded. Once you've opened a console with the 3.8mm driver, a dirty pin connector is the next common cause of games not reading — cleaning it is a maintenance step, not a repair.
• Game Boy Color TFT LCD Backlight Kit - Cloud Game Store: A Game Boy Color backlight kit with a transflective display that works in direct light, requires no shell modification for regular GBC shells, and includes a shielding sticker and brightness adjustment without soldering wires. If you're already opening a Game Boy Color to replace a battery or clean it, this kit is a practical upgrade to do in the same session since no shell cutting is needed.