Drill bit sizes
You can see drill bit sizes and dimensions of all TTP HARD cobalt bits below.
First chart is for Imperial drill bits and second is for metric sizes.
Why Trust These Drill Bit Sizes?
All sizing shown here is based on real product specs from our SGS-tested cobalt drill bits. With over 20 years of experience supplying metal drill bits, we’ve helped thousands of professionals find the exact size and performance they need.
- ✔ M35 cobalt drill bits – 5% cobalt through the body
- ✔ SGS-certified hardness for consistent performance
- ✔ Trusted by mechanics, farmers, engineers & repair crews
Whether you’re working with stainless steel, cast iron, or HARDOX450, these size charts match the exact cobalt bits we ship daily from our U.S. warehouse.
For further reading check out our article which will guide you in choosing the ideal drill bit sizes for aluminium
Not Sure What Size or Set You Need?
Here’s how professionals choose their drill bits:
- Drilling hard metals? Go cobalt. Our M35 bits handle stainless steel, HARDOX450, and tough alloys.
- Need full coverage? Choose a 21-piece or 29-piece set (Imperial), or 19-piece or 25-piece set (Metric).
- Just replacing a broken bit? Scroll up and click the exact size you need — we ship all individual sizes direct.
💡 Tip: Always use a cutting paste when drilling metal. It protects your bits and helps you drill cleaner, faster holes.
Choosing the right size matters, but using the correct drill bits for metal is equally important
Click on Imperial size below for more information (1/16″ to 1/2″)
Also 21 & 29 Piece drill sets
Cover all bases and get either the small 21 piece drill bit set or the complete 29 piece drill set.
Frequently Asked Questions
Are your drill bits suitable for stainless steel?
Yes — all TTP HARD bits are made from 5% M35 cobalt and can drill stainless steel, HARDOX450, cast iron, and other hard metals. We recommend using a low drill speed and our CUT-IT paste for best results.
Can I buy individual drill bit sizes?
Absolutely. You can order any size from 1/16″ to 1/2″ (imperial) or 1mm to 13mm (metric) directly on this page. Each size links to a dedicated product page with full specs and pricing.
What’s the difference between the 21-piece and 29-piece sets?
The 21-piece set includes bits from 1/16” to 3/8” in 1/64” increments. The 29-piece set adds every size up to 1/2”, making it a complete professional kit for any workshop or mobile job.
Do I need to use a cutting paste?
Yes — for drilling into any metal, a cutting paste like CUT-IT is essential. It reduces friction and heat, extends the life of your drill bits, and helps you create cleaner holes. Right now, you can get a full-size CUT-IT for just $10 with any drill bit set.
What makes your cobalt bits different?
Our M35 cobalt drill bits contain 5% cobalt through the entire body (not just a coating). They’ve been SGS-tested for hardness and are trusted by mechanics, engineers, farmers, and heavy machinery operators worldwide.
Looking for more information on Cobalt Drill Bits?
Why not invest in a full Metric Kit, either the small 19 piece set or our larger 25 piece set which has 1mm up to 13mm.
We now ship our cobalt drill bits to Australia direct from our UK warehouse
Remember to always use a metal cutting paste when drilling metal
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