What Size Drill Bit for a 3/4” NPT Tap?

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The ¾”  NPT tap is a common tap mainly used to cut pipes’ internal threads.¾” NPT taps are generally made of steel and are usually heavier than most taps If you want to know what size drill bit for a ¾” NPT tap is, read further.

What Size Drill Bit for a 3/4” NPT Tap?

A ¾” NPT Tap needs a size drill bit of 59/64 inches or 0.9219 inches in decimals. NPT taps are also called pipe taps, and don’t confuse them with NPTF taps and tapered taps like the ⅞- 9 tap.

Gold drill bits placed upright on its box

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 ½” NPT tap. 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

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.

Avoid Jamming Your Drill

One common thing when using large drill bits is jamming. It’s a common mistake amateur drillers make since they usually apply more pressure when drilling, which leads to jamming. You should learn how to avoid jamming your drill.

Man using a drill to fasten a screw in a wooden panel

When you jam your drill, you might have to replace the tip, and your drill’s lifespan will shorten. You want to avoid spending more than you should when it’s avoidable. One thing you can do is not apply too much pressure when drilling.

Also, feel the drill and spot when you think it is slowing down. Pull it out when you think it’s slowing down and let it cool for a while, cleaning off any debris stuck in the drill.

Keep A Spare Set of Drill Bits

You never know when your drill bit dulls or breaks. So having spare sets help replace them immediately. Another benefit of using two sets of drill bits is you can alternate them, so you have a sharp one at the ready. 

Some professional drillers even use them at the same time. They use the new set of drills to drill a hole. The premise is that it keeps the sharper set for longer. After starting the hole, they switch to the old and sharpened set to finish the drilling making it less prone to dulling. 


¾” NPT taps need a large drill bit size of 59/64 inches and can be used for a wide range of materials. They’re mostly used for cleaning and re-threading. If you’re gonna use them, make sure to have a sealer for the threads.