Drill Bit Shank Types & Sizing
Tool Drives & Bit Shanks · 7 specs
Direct Answer
Drill bit shanks are standardized under ISO 296, DIN 338, and proprietary power tool systems into Straight Round Shanks, 1/4" Quick-Change Hex Shanks (ISO 1173), SDS-Plus (10 mm / 2-groove), SDS-Max (18 mm / 3-groove), and Morse Taper (MT1–MT5) industrial spindle shanks.
Source: ISO 1173:2001 Assembly tools for screws and nuts — Drive ends / ISO 296 (Morse Tapers) / DIN 338 · Last reviewed Aug 28, 2026
Specs
| Governing Standards | ISO 1173 / ISO 296 / DIN 338 / Bosch SDS Standard |
| Straight Round Shank | Universal smooth cylindrical shank held in 3-jaw keyed or keyless chucks (0.5 mm to 13.0 mm / 1/2") |
| 1/4-Inch Hex Shank (Form E 6.3) | 6.35 mm (1/4") with power ball detent groove (ISO 1173 Form E 6.3) | Prevents bit spin-out in impact drivers |
| SDS-Plus Shank (10 mm) | 10 mm diameter shank with 2 open drive splines + 2 closed ball-locking grooves | Rotary hammers up to 4 kg |
| SDS-Max Shank (18 mm) | 18 mm diameter heavy-duty shank with 3 open splines | Heavy demolition hammers and core drilling (5+ kg) |
| Morse Taper 2 (MT2) | Taper 1:20.020 | Large diameter: 17.780 mm (0.700") | Drill presses, metal lathes, magnetic base drills |
| Morse Taper 3 (MT3) | Taper 1:19.922 | Large diameter: 23.825 mm (0.938") | Industrial radial arm drills |
Global Drill Bit Shank Specification & Compatibility Matrix
| Shank Type | Shank Diameter / Geometry | Retention Mechanism | Maximum Recommended Drilling Size | Primary Chuck System |
|---|---|---|---|---|
| Straight Round | 1.0 mm to 13.0 mm (1/2") cylindrical | Friction clamping via 3 jaws | Wood: 25mm / Steel: 13mm | 3-Jaw Keyed / Keyless Chuck |
| 1/4" Hex (Form E 6.3) | 6.35 mm (0.250") Hexagonal | Ball Detent Spring Collar | Wood: 38mm / Steel: 10mm | Cordless Impact Driver 1/4" Collet |
| SDS-Plus | 10.0 mm (0.394") Grooved | Spring-loaded locking balls in slots | Concrete: 4 mm to 32 mm | Rotary Hammer SDS-Plus Chuck |
| SDS-Max | 18.0 mm (0.709") Splined | 3 sliding splines + locking segments | Concrete: 12 mm to 52 mm (Core 150mm) | Heavy Demolition SDS-Max Chuck |
| Morse Taper (MT2) | 17.78 mm tapered (1:20 taper) | Self-holding friction + Tang drive | Steel: 14 mm to 23 mm | Drill Press / Lathe MT2 Spindle |
| Morse Taper (MT3) | 23.83 mm tapered (1:19.92 taper) | Self-holding friction + Tang drive | Steel: 23 mm to 32 mm | Industrial Radial Drill MT3 Spindle |
How SDS Rotary Hammer Splines Deliver Linear Impact
Unlike standard 3-jaw chucks that clamp tightly onto a drill bit shank, an SDS chuck (Special Direct System) allows the bit to slide back and forth like a piston inside the barrel by 10 to 15 mm. The internal pneumatic striker pounds directly against the hardened back face of the bit without energy loss through chuck jaws.