SDS-Plus vs SDS-Max: Technical Comparison & Compatibility Matrix
SDS (Slotted Drive System) bits power millions of rotary hammers and percussion drills worldwide. But “SDS” isn’t one standard—it’s a family of systems. SDS-Plus and SDS-Max are the two most common variants in UK workshops, and they are completely incompatible with each other.
This guide explains the technical differences, helps you identify which system your drill uses, and shows you exactly which bits fit which tools. We’ll also cover the less common variants (original SDS, SDS-Quick, and SDS-Top) so you understand the full picture.
SDS-Plus: The Entry-Level Percussion Standard
Physical Specifications
Shank diameter: 10mm
Groove design: 2 open + 2 closed grooves
Length: Variable (bits typically 75–350mm total length)
Bearing length: 15–25mm (guides the shank in the chuck)
SDS-Plus was the original SDS standard, released by Bosch in the 1970s. The “Plus” designation came later, when SDS-Max was introduced, but the two terms are used interchangeably today. The 10mm shank with its distinctive groove pattern allows the chuck to grip the bit and transmit hammer force efficiently while minimising runout.
Typical Applications & Power Ranges
SDS-Plus is the workhorse of UK construction and DIY:
- Entry-level: Consumer rotary hammers (400–800W). Ideal for occasional masonry drilling and light percussion work.
- Mid-range: Professional SDS-Plus hammers (500–1000W). Heavy-duty masonry, concrete drilling, and controlled chiselling work.
- Cordless: 18V and 20V SDS-Plus hammers from Makita, DeWalt, Milwaukee. Popular for site work where mains power isn’t available.
Typical Bit Sizes for SDS-Plus
SDS-Plus bits range from very small to moderately large:
- Masonry bits: 4–30mm diameter (most common: 6–16mm)
- Concrete bits: 4–32mm diameter
- Flat chisels: 20–60mm width
- Pointed chisels: Narrow taper (for controlled chasing)
The largest practical SDS-Plus masonry bit is around 30–32mm. Beyond that, rotary hammer manufacturers recommend SDS-Max due to torque and bearing stress concerns.
SDS-Max: The Heavy-Duty Professional Standard
Physical Specifications
Shank diameter: 18mm
Groove design: 3 open + 2 closed grooves
Length: Variable (bits typically 150–500mm total length)
Bearing length: 20–35mm
SDS-Max was introduced in the 1980s for heavy-duty applications. The larger 18mm shank and additional open groove allow the chuck to transmit significantly more hammer force and torque. This system dominates in professional drilling shops, construction sites, and industrial settings where power and precision matter most.
Typical Applications & Power Ranges
- Professional rotary hammers: 1200–2500W. Sustained heavy drilling, demolition, and fast chasing.
- Breaker hammers: 1500–4000W. Breaking concrete, controlled demolition, large-area chasing.
- Cordless industrial: 18V MX FUEL (Milwaukee) and 54V systems. Site-based heavy work.
Detailed Compatibility Matrix
| Chuck System | Shank Size | Compatible Bits | Incompatible With | Typical Tools |
|---|---|---|---|---|
| SDS-Plus | 10mm | SDS-Plus bits, Original SDS bits | SDS-Max, SDS-Quick | Consumer & mid-range rotary hammers, cordless 18V/20V |
| SDS-Max | 18mm | SDS-Max bits only | SDS-Plus, SDS-Quick | Professional rotary hammers 1200W+, breaker hammers |
| Original SDS | 10mm | SDS-Plus bits, Original SDS bits | SDS-Max, SDS-Quick | Bosch rotary hammers (1970s–1990s) |
| SDS-Quick | 10mm | SDS-Quick bits only | SDS-Plus, SDS-Max | Bosch Uneo cordless drills (proprietary) |
How to Identify Your Drill’s SDS System
Check your drill’s user manual or spec sheet. Alternatively, examine a bit that fits: 10mm shank with 2 open grooves = SDS-Plus; 18mm shank with 3 open grooves = SDS-Max. Use digital callipers if unsure, or look up your drill model number on the manufacturer’s website.
SDS-Plus vs SDS-Max: Which Should You Choose?
Choose SDS-Plus if you: drill occasional masonry, need a lighter tool (2–3kg), work mainly in soft brickwork, want lower cost (tools start under £80), or prefer cordless convenience.
Choose SDS-Max if you: do heavy-duty professional work, regularly drill holes larger than 25mm in reinforced concrete, need speed for high-volume jobs, or can afford the higher cost (£300+).
Recommended SDS-Plus Bit Sets (Amazon UK)
Makita P-90185 SDS-Plus Bit Set — Comprehensive starter with 4–10mm bits. Professional-grade quality. Around £25–35.
DeWalt DT60125 SDS-Plus Masonry Bits — Heavy-duty set: 5, 6, 8mm. Reliable in tough materials. £15–20.
Bosch SDS-Plus Bit Assortment — 4, 6, 8, 10mm bits from the SDS inventors. £18–28.
Recommended SDS-Max Bit Sets (Amazon UK)
Makita P-16814 SDS-Max Bit Set — Professional: 16–32mm plus chisel. £35–50.
Milwaukee Shockwave SDS-Max — 20, 25, 32mm impact rated. £30–40.
Common Mistakes
Assuming “SDS” means any bits fit: SDS is a family, not a single standard. Always check the suffix (Plus or Max).
Using adapters instead of correct bits: An SDS-Max to SDS-Plus adapter creates dangerous runout. Buy the correct bits.
Buying very cheap generic bits: Budget bits wear out quickly in hard masonry. Invest in established brands.
Return to the Drill Bit Compatibility Hub for more guides, or explore our material-specific reference.