What is the difference between 4 mm and 6.35 mm screwdriver bits?

The main difference is the shank size, torque capacity, and intended application.

4 mm bits: mainly used for precision screwdrivers and electronics repair

6.35 mm / 1/4-inch bits: mainly used for general-purpose screwdrivers, ratchet tools, electric screwdrivers, and higher-torque applications

The key differences are:

Shank size: 4 mm bits have a smaller hex shank; 6.35 mm bits use the standard 1/4-inch hex shank

Application: 4 mm bits are better for phones, laptops, cameras, watches, and other small electronics

Torque capacity: 6.35 mm bits are stronger and better suited for furniture, appliances, machinery, automotive work, and general assembly

Tool size: 4 mm bits work with slimmer precision handles, while 6.35 mm bits require larger holders

Access: 4 mm bits are easier to use in narrow or recessed spaces

Compatibility: 6.35 mm bits have wider compatibility with standard bit holders, ratchet screwdrivers, drills, and power tools

Bit profiles: both sizes can be produced in Phillips, Slotted, Torx, Hex, Security Torx, and other profiles, but specialty electronics profiles are more common in 4 mm sets

For precision repair, 4 mm is usually the better choice. For general repair or higher-torque work, 6.35 mm / 1/4-inch bits are more suitable.

ToolQeen screwdriver sets can be configured with both H4 and H6.35 bits, including different lengths, S2 or CR-V materials, hardness levels, bit combinations, handles, cases, and private-label packaging for OEM and wholesale projects.