What Size Drill Bit for 2” NPT Tap?

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The 2” NPT tap is a common tap mainly used for cleaning or re-threading damaged or jammed pipe threads. 2” NPT taps are generally made of steel and are usually heavier than most taps. If you want to know the size drill bit for a 2” NPT tap, read further.

What Size Drill Bit for a 2” NPT Tap?

A 2” NPT Tap needs a size drill bit of 2 7/32 inches or 2.2188 inches in decimals. NPT taps are also called pipe taps, and don’t confuse them with NPTF taps and tapered taps like the 5-40 tap.

Drill bits, screws and other tools mixed together in a plastic container

NPT taps can be carbon steel, HSS, or Interrupted thread NPT taps. Carbon steel NPT taps are generally used for cleaning or re-threading damaged or jammed pipe threads like the 1 1/2″ NPT tap with a size drill bit of 1 47/64″. High-speed NPT pipes are for making new threads and for re-threading also.

If you plan to use NPT threads, do know they require a sealer like Teflon tape or pipe compound.

Tips for Using Large Drill Bits

Monitor Your Progress When Drilling

As you are drilling, check your work to see if there are any adjustments you need to do. If there are lugs or jams, remove it and clean them up. You can use the bit to clear the hole from debris.

Make it a habit to pull out the drill bit every now and then and blow it off. This is important when you are drilling wood. Any flakes or chips of wood can get stuck in the bit.

The flakes and chips can make your drill bit heat up faster. This may be unnoticed by you. When your drill bit gets hot, it will function effectively less.

Don’t Use Excessive Force

Large drill bits naturally make people think that you have to use more power. However, that is not the case. It’s better to focus on precision instead of power. When drilling, you must hold the drill vertically at all times for consistency.

Cordless drill with screws placed on the table

You want to hold a 90-degree angle while you let the bit drill for you. A slight bend could cause the hole to be unaligned, and the exit hole will not be where you want it to be.

It’s wise to not use excessive force that can affect your accuracy and stability when holding the drill.

X Marks the Spot

When you’re drilling a pilot hole, it’s recommended to tape an X over the spot. You can use painter’s tape to mark it. The tape helps reinforce the wood or other surface to prevent cracking.

Cracking often happens with large drill bits since I’m handling big drilling projects. Reinforcing the surface isn’t bad when drilling since you don’t want cracks forming within your workpiece.

Aside from reinforcing with tape, you can also avoid cracking by drilling at the right depth. Drilling too much may cause cracking, so you must measure how deep you are drilling.


2” NPT taps need a large drill bit size of 2 7/32 inches and can be used for various materials. They’re mostly used for threading various materials. If you’re gonna use them, make sure to have a sealer for the threads.