Best .370 Drill Bit Options: Sizes, Alternatives, and Buying Tips
No listed product is an exact 0.370-inch drill bit. The closest drill-bit option is a 9.5 mm bit, measuring about 0.374 inch; the listed 0.370-inch tool is a chucking reamer, not a drill bit. For a true 0.370-inch hole, choose a bit explicitly marked 0.370 inch, or use an appropriately sized drill followed by a reamer when the application requires a more controlled finish.
| Product | Best for | Size or type |
|---|---|---|
| uxcell M2 HSS | Closest listed drill-bit size | 0.374 inch |
| Meccion M35 cobalt | Heat-resistant metal drilling | 37/64 inch |
| Drill America reduced shank | Using a larger bit in a 1/2-inch chuck | 37/64 inch |
| M35 cobalt split-point bit | Hard metals and accurate starting | 37/64 inch |
| Drill America reamer | Finishing a predrilled hole | 0.370 inch |
uxcell 9.5 mm M2 HSS Drill Bits
Best for: Buyers who need a drill bit close to 0.370 inch and can accept a slightly larger 0.374-inch hole. This two-piece set uses M2 high-speed steel and has a 135-degree split point, features suited to drilling metal and helping the bit start with less walking.
The listed cutting-edge and shank diameters are both 9.5 mm, or 0.374 inch. The bits have an 81 mm cutting-edge length and 125 mm overall length. Black nitride and gold titanium coatings are described as helping with lubrication and corrosion resistance, while the spiral flutes carry chips away.
Limitation: At 0.374 inch, this is not an exact 0.370-inch drill bit. Avoid it when the finished hole must be precisely 0.370 inch without further machining.
Meccion 37/64-Inch M35 Cobalt Bit
Best for: Metalworking buyers who need a cobalt bit for demanding materials rather than a near-0.370-inch diameter. Its 5% cobalt M35 high-speed steel construction is specified for cast iron, stainless steel, hard metal, copper, and similar materials. A 135-degree pilot-point tip is intended to reduce walking.
The product is listed as 37/64 inch, which equals approximately 0.578 inch. That is substantially larger than 0.370 inch. Its heat-treated construction and stated hardness up to HRC 67 make it a relevant option when material and heat resistance matter more than matching the requested diameter.
Limitation: Do not substitute this bit for a 0.370-inch bit; it creates a much larger hole.
Drill America 37/64-Inch Reduced-Shank Bit
Best for: Users who need a 37/64-inch cutting diameter but have a drill chuck that accepts a 1/2-inch shank. This contractor-grade bit is made from M1 high-speed steel and has a 3-flat, 1/2-inch shank. The 135-degree split point is designed to self-center and reduce walking.
It is listed for drilling materials in the iron and steel families, including aluminum, iron, and steel. The reduced shank addresses chuck capacity; it does not reduce the hole diameter. The cutting diameter remains 37/64 inch, approximately 0.578 inch.
Limitation: This bit is not close to 0.370 inch in cutting size. Choose it only when the larger diameter is intentional.
37/64-Inch M35 Cobalt Split-Point Bit
Best for: Buyers drilling stainless steel, cast iron, hardened metal, copper, or non-ferrous alloys who need a larger hole. This bit uses 5% cobalt HSS, with a stated hardness up to HRC 67. Its 135-degree split point is intended to make immediate contact and reduce wandering; the round shank supports concentric drilling.
The manufacturer describes the material as heat resistant for extended high-temperature applications and states up to five times the life of standard HSS bits. Its size is 37/64 inch, or about 0.578 inch, so it should be compared with other larger cobalt bits—not with a true 0.370-inch bit.
Limitation: Its diameter is far larger than the requested size. The listed performance claims are product specifications, not independent test results.
Drill America 0.370-Inch Chucking Reamer
Best for: Buyers whose priority is a 0.370-inch finished hole and who understand that a reamer is a finishing tool, not a standard twist drill. This straight-shank chucking reamer is made from high-speed steel. Its uncoated surface and round shank are specified for general-purpose use with a variety of toolholding systems.
A reamer is generally used to refine a hole that has already been drilled, rather than to create a hole from solid material. This makes the product relevant to the requested final diameter, but it does not replace a 0.370-inch drill bit when drilling directly is required.
Limitation: The listing identifies this as a reamer, not a drill bit, and does not provide enough detail here to determine the required starting-hole size for a particular job.
Buying Guide: How to Choose a .370 Drill Bit
Do you need a 0.370-inch hole or a 0.370-inch drill?
These are different requirements. A drill bit cuts a hole; a reamer typically refines a predrilled hole. If the job calls for a 0.370-inch finished diameter, confirm whether the plan specifies a drill, a reamer, or a drilling-and-reaming sequence. The listed reamer is exactly 0.370 inch, while the closest listed drill bit is 0.374 inch.
How close is 9.5 mm to .370 inch?
9.5 mm converts to approximately 0.374 inch, about 0.004 inch larger than 0.370 inch. That difference may matter in fitted parts or other dimension-sensitive work. Check the required tolerance before choosing the uxcell bit.
Should you choose HSS or cobalt?
M2 and M1 high-speed steel options are listed for general metal drilling, while the M35 cobalt bits are specified for heat-resistant drilling in tougher metals. Material choice does not compensate for a wrong diameter: the three 37/64-inch bits are about 0.578 inch across regardless of their steel type.
What else should you check?
- Cutting diameter: Verify the decimal or fractional size, not just the shank size.
- Chuck capacity: The Drill America reduced-shank model has a 1/2-inch shank and a larger cutting diameter.
- Point geometry: A 135-degree split point is listed on several options to help reduce walking.
- Material and process: Match the bit material to the workpiece, and follow the toolmaker’s guidance for drilling and finishing.
Frequently Asked Questions
Is 37/64 inch the same as .370 inch?
No. 37/64 inch is approximately 0.578 inch, which is much larger than 0.370 inch.
Is a 9.5 mm drill bit .370 inch?
No. A 9.5 mm bit is approximately 0.374 inch, so it is about 0.004 inch larger than 0.370 inch.
Which listed product is exactly .370 inch?
The Drill America DWR product is listed as a 0.370-inch chucking reamer. It is not identified as a drill bit.
Can a .370-inch reamer drill a hole from solid material?
The listing describes a chucking reamer, a finishing tool. It does not establish that the tool is intended to drill from solid material; check the tool’s instructions and the job requirements.
What should I buy for an exact .370-inch drilled hole?
Look for a drill bit explicitly labeled 0.370 inch and verify its stated diameter and application. None of the listed drill bits is that exact size.