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If you've ever shopped for a rotary hammer drill or demolition hammer you've seen the terms SDS-Plus and SDS-Max. Both are SDS (Slotted Drive System) chuck formats — but they're designed for very different applications. Here's exactly what the difference is and which one you need.
What Is SDS?
SDS stands for Slotted Drive System (originally from the German Steck-Dreh-Sitzt — insert, twist, lock). Unlike a standard keyless chuck that grips a round shank with friction, SDS chucks use a locking mechanism that engages slots in the bit shank. This allows the bit to slide back and forth (for the hammer action) while remaining locked against rotation.
The result is more efficient energy transfer to the material — more impact power reaches the bit rather than being absorbed fighting the chuck.
SDS-Plus
SDS-Plus is the standard for rotary hammer drills used in light to medium construction work. The shank diameter is 10mm and bits are available in a huge range of sizes and types.
SDS-Plus is used for:
Typical SDS-Plus tools:
SDS-Max
SDS-Max uses a larger 18mm shank diameter — accepting bigger, heavier chisels and core bits. It's the professional standard for demolition hammers and heavy-duty breaking work where SDS-Plus simply isn't powerful enough.
SDS-Max is used for:
Typical SDS-Max tools:
Key Differences at a Glance:
| Feature | SDS-Plus | SDS-Max |
|---|---|---|
| Shank diameter | 10mm | 18mm |
| Impact energy | Up to ~8 joules | 20-80+ joules |
| Max drilling | Up to ~40mm | 40mm+ core drilling |
| Weight | Lighter | Heavier |
| Best for | Drilling & light chiselling | Heavy breaking & demolition |
| Cost | Lower | Higher |
| Bit availability | Very wide range | Professional range |
Can I Use SDS-Plus Bits in an SDS-Max Tool?
No — the shanks are completely different sizes and are not interchangeable. Always match your bits and chisels to the chuck format of your tool.
Which Do You Need?
Choose SDS-Plus if:
Choose SDS-Max if:



