Screwdriver bits are the removable tips that fit into bit drivers, power drills, and impact drivers. They all use a standard ¼″ (6.35 mm) hex shank, making them interchangeable across tools from any manufacturer.
Insert Bits vs Power Bits
Insert bits are 25 mm (1″) long and fit into bit holders or compact drivers. Power bits are 50 mm (2″) or longer and fit directly into drill chucks or impact drivers without a holder. For deep-set screws or working at arm's length, power bits give better reach.
Bit Types and What They Fit
| Bit Type | Designation | Fits | Common Sizes |
|---|---|---|---|
| Phillips | PH | Phillips cross-head screws | PH1, PH2, PH3 |
| Pozidriv | PZ | Pozidriv screws (tick-marked cross) | PZ1, PZ2, PZ3 |
| Flat / Slotted | SL | Slotted screws | 4 mm, 5.5 mm, 6.5 mm |
| Torx | T | Six-point star screws | T10, T15, T20, T25, T30 |
| Security Torx | T-H | Pin-in-centre Torx screws | T8H, T10H, T15H, T20H |
| Hex (Allen) | H | Hexagonal socket screws | 3 mm, 4 mm, 5 mm, 6 mm |
| Square (Robertson) | R | Square recess screws | R1, R2, R3 |
| Torx Plus | IP | Torx Plus high-torque screws | IP10, IP15, IP20, IP25 |
What types of screwdriver bit sets are there
Screwdriver bits and bit sets are the hardened tips that go in a bit holder, drill or impact driver, sold as a case of sizes rather than one at a time. Sets are grouped by the job they cover, and the case usually tells you which you are looking at.
- General purpose sets: 25 mm insert bits in PH, PZ, slotted, Torx and hex, with a magnetic holder. The 30 to 60 piece case most trades carry
- Power bit sets: 50 mm and longer bits that fit a drill chuck or impact driver directly, for driving screws at arm's length
- Impact rated sets: torsion zone bits for impact drivers, usually PH2, PZ2 and Torx T20 to T30 in bulk because those are what wear out
- Security bit sets: pin-in-Torx, spanner, tri-wing, pentalobe and one-way bits for tamper-resistant screws on consoles, appliances and public fixtures
- Precision sets: 4 mm shank micro bits from PH000 to T6 for phones, laptops and electronics, with a fine-control handle
- Trade specific sets: Torx Plus and E-Torx for automotive, square drive for decking and cabinetry, hex and Torx for machinery
Bit Materials
- S2 tool steel - the industry standard for quality bits. Hardened to HRC 58–62 for durability and resistance to rounding
- Chrome vanadium (CRV) - good all-round steel, slightly softer than S2 but more flexible (less brittle)
- High-speed steel (HSS) - more heat-resistant, used for some specialty and industrial bits
- Soft alloy / unmarked - cheap bits that round out quickly. Avoid for anything beyond occasional use
Impact-Rated Bits
Standard bits shatter under the repeated concussive blows of an impact driver. Impact-rated bits (often marked "impact" or torsion) are made from slightly softer, more flexible steel with a torsion zone that absorbs shock. If you use an impact driver, always use impact-rated bits - standard bits will snap.
A magnetic bit holder is worth more than a magnetic bit. It magnetises any bit you insert, and you only need one holder instead of paying extra for magnetic versions of every bit size.
