3/8-Inch vs. 1/2-Inch Chuck: Which Drill Size Do You Need?
The chuck is the clamp at the front of a drill that grips the bit. Its size, usually 3/8" or 1/2", is the thickest bit shank it can hold. It says nothing about the size of hole you can drill, because many bits for bigger holes have a narrower shank. To see what else changes with the chuck, we read Milwaukee's own pages tonight for two M12 drill/drivers that run on the same batteries. We haven't tested either one hands-on, so there are no ratings here.
| Drill | Maker-listed specs | Price |
|---|---|---|
| Milwaukee M12 Subcompact Brushless 3/8" Drill/Driver Kit (3401-22) | 3/8" all-metal chuck; 12V; brushless; 350 in-lbs max torque; 0-1,550 RPM; 2 speeds; 12 clutch settings; 5.4" long; 1.58 lb without battery; Milwaukee says the kit includes two M12 batteries, a charger and a contractor bag | Check current price |
| Milwaukee M12 FUEL 1/2" Drill Driver (3403) | 1/2" all-metal ratcheting keyless chuck; 12V; POWERSTATE brushless; 400 in-lbs max torque; 0-1,550 RPM; 2 speeds; 12 clutch settings; 5.95" long; 2.1 lb without battery | Check current price |
One caution: tonight the 3403-22 kit link opened a page titled "M12 FUEL 1/2" Drill Driver Bare Tool," and its spec list mixed kit and tool-only fields. So we've only listed the tool's own specs above, not what comes in the box. Check the listing you buy to see whether batteries and a charger are included (see bare tool vs. kit).
What the numbers tell you
On paper, these two are close. Both list the same top speed, two speeds and 12 clutch settings. The 1/2" model lists 50 more in-lbs of torque (400 vs. 350) and a FUEL motor. In return it's about half an inch longer and about half a pound heavier without a battery, going by Milwaukee's figures. The bigger chuck mostly buys you the ability to grip thicker bit shanks.
Which one to buy
A 3/8" chuck is enough if your jobs are pilot holes, hanging shelves and curtain rods, assembling furniture and driving screws. Ordinary twist bits up to 3/8" and bits with 1/4" hex shanks fit it, and the smaller drill is easier to handle overhead and in tight spots.
Get a 1/2" chuck if you expect to use bits with shanks thicker than 3/8", such as some large twist bits, mixing paddles or bigger hole-saw arbors. The shank size is printed on the bit's package, so check it before you buy the drill. If you need to drill into masonry, look at a hammer drill instead (see hammer drill vs. drill/driver).
Both of these run on M12 batteries, so whichever you pick, stay on one platform. See 12V vs. 18V/20V, brushed vs. brushless and best drill for homeowners.
Sources: https://www.milwaukeetool.com/products/details/m12-subcompact-brushless-3-8-drill-driver-kit/3401-22, https://www.milwaukeetool.com/products/details/m12-fuel-1-2-drill-driver-kit/3403-22. Specs checked on the manufacturer pages on Oct 31, 2026.