Rivet Nut Drill Bit and Hole Size Chart

Drilling the correct hole size is the most important step in a rivet nut installation. An undersized hole prevents the rivet nut from seating — it will jam during install or set crooked. An oversized hole reduces the grip of the knurled flange and lets the rivet nut spin under torque. This chart covers the recommended drill bit diameter for every RivetKing IKF and ISR rivet nut size we stock, plus the matching Triumph drill bit SKU we carry in stock. Bookmark this page for quick reference on your next project.

IKF Series Rivet Nut Drill Bit Chart — Inch Sizes

The RivetKing IKF series is the standard knurled-body, low-profile-head rivet nut for use when you know your panel thickness. The hole must be drilled to the diameter shown below with a tolerance of +0.006" / -0.000" — the closest fractional or letter-size drill bit is listed for each thread size.

Tolerance note: The hole sizes above are nominal. RivetKing’s published tolerance is +0.006" on the high side, so a slightly larger drill (within tolerance) is acceptable. Drilling under nominal causes the rivet nut to bind during installation.

IKF Series Rivet Nut Drill Bit Chart — Metric Sizes

Metric IKF rivet nuts are sized to standard ISO metric thread specs. The closest standard drill bit (fractional, letter, or metric) is listed below. Tolerance on metric hole sizes is +0.15mm / -0.00mm.

ISR Series (Swaging) Rivet Nut Drill Bit Chart

The RivetKing ISR series is the swaging-style rivet nut for blind-hole installations and applications where the panel thickness is unknown or variable. Hole size for ISR varies slightly by sheet thickness — the value below is the recommended drill for the most common sheet thickness range (0.030"-0.090"). Thicker sheets may require a slightly larger hole — consult the RivetKing catalog for the full thickness/hole matrix.

ISR sizing note: Unlike fixed-grip IKF rivet nuts, the ISR series has unlimited maximum grip and is designed for use in any sheet over 0.030" thick. Because of the swaging action, hole size has a slightly wider acceptable tolerance than IKF.

Drill Bit Selection by Workpiece Material

The rivet nut hole size is determined by the rivet nut you’re installing. The type of drill bit you should use is determined by the material you’re drilling into. Here’s how to choose:

Mild Steel Sheet Metal (the most common case)

• HSS (high-speed steel) twist drills work well for occasional installs — the Triumph T1HD+ / T2HD+ / T3HD+ / MM1HD HSS series is the right starting point.
• For higher volume or harder steel, step up to HSS-Co (cobalt) for longer life.
• Use cutting fluid or oil to extend bit life and produce a cleaner hole.

Stainless Steel Sheet

• HSS-Co (cobalt) is required — standard HSS will dull quickly and work-harden the stainless, making subsequent holes worse.
• Use slow speed and steady feed pressure. Stainless punishes intermittent contact.
• Cutting fluid is essential, not optional.

Aluminum and Non-Ferrous

• Standard HSS works fine and cuts faster than in steel.
• Watch for chip welding — aluminum sticks to the flutes if speed is too high or the bit is dull. Use a wax lubricant if cutting a lot of aluminum.

Production Volume / Repetitive Drilling

• Solid carbide or carbide-tipped drill bits offer dramatically longer life on production runs — cost more per bit, much less per hole.
• Match your drill press / CNC RPM to the bit manufacturer’s recommendation for maximum life.

Very Thin Gauge Sheet (under 0.040")

• A step drill bit produces a cleaner round hole in thin sheet than a twist drill, which can grab and tear the sheet.
• Step bits are sized in increments — pick one that includes the rivet nut hole diameter you need.

Key Terms & Rivet Nut Drilling Tips

Definitions

• Hole size (or drill diameter): The diameter of the round hole drilled through the panel. The rivet nut body slides through this hole during installation.
• Grip range: The range of panel thicknesses a given rivet nut size will accommodate. IKF series has fixed grip ranges; ISR series has unlimited maximum grip.
• Tolerance: The allowable variation in hole size. RivetKing’s published tolerance for IKF is +0.006" / -0.000" (drill slightly oversize is OK, undersize is not).
• Knurled body: The grooved or ridged body of the rivet nut. The knurls bite into the hole wall during installation to prevent rotation under torque.
• Spin-out: When the rivet nut rotates inside the hole during installation or when a bolt is tightened. Caused by an oversized hole, smooth hole walls, or insufficient knurl engagement.
• Step drill bit: A stepped, conical drill bit that drills multiple sizes in one bit. Useful for thin sheet metal where a twist drill might tear the material.

Drilling Tips for Rivet Nut Installations

• Match the drill exactly to the rivet nut. Eyeballing or substituting a nearby fractional drill is the #1 cause of rivet nut failure. The chart above shows the best match for every size we stock.
• Drill perpendicular to the panel. An angled hole prevents the flange from seating flat and reduces grip.
• Deburr the hole on both sides. A deburring tool or a larger drill bit held by hand removes the burr ring on the back side of the panel. Burrs prevent the rivet nut body from collapsing properly.
• Test fit before setting. Drop the rivet nut into the hole — the knurled flange should sit flat and the body should slide through with light interference. If the rivet nut binds before the flange touches the panel, the hole is too small or the panel has burrs. If the rivet nut is loose enough to wobble, the hole is too large.
• Use a sharp drill bit. A dull bit produces an oversized, out-of-round hole. The knurls won’t engage and the rivet nut will spin under torque. Replace bits when they stop cutting cleanly.
• For stainless rivet nuts in stainless panels: use HSS-Co cobalt bits, slow speed, and continuous cutting fluid. This is the most demanding rivet nut application.

Frequently Asked Questions

What happens if my hole is slightly too small?

The rivet nut body won’t fit cleanly through the hole during installation. You’ll feel resistance trying to seat the flange against the panel. Force can deform the rivet nut body or strip the threads on your installation tool mandrel. If you’re close (within a few thousandths) you can sometimes ream the hole — but it’s safer to drill fresh with the correct size bit.

What happens if my hole is too large?

The knurled flange can’t bite into the hole wall, so the rivet nut spins when you try to tighten a bolt into it. The whole point of the knurl is to grip — an oversized hole defeats it. If the hole is just slightly oversized you can sometimes save the install with a drop of threadlocker on the rivet nut body before setting. For significantly oversized holes, move to a larger rivet nut size or patch the panel.

Do I need a different drill bit for stainless rivet nuts vs steel rivet nuts?

No. The drill bit is for the panel you’re drilling, not the rivet nut. The drill bit diameter is determined by the rivet nut size. The drill bit material (HSS vs cobalt) is determined by what the panel is made of. A 1/4-20 stainless rivet nut going into a mild steel panel uses the same drill bit (25/64" HSS) as a 1/4-20 zinc-plated steel rivet nut going into the same panel.

Can I use a step drill bit for rivet nut holes?

Yes, for thin sheet metal a step drill produces a cleaner round hole than a twist drill and is less likely to grab or tear the panel. Just make sure the step you stop at matches the exact rivet nut hole size needed. Step drills are ideal for thin gauge sheet (under 0.040") where a twist drill might cause the sheet to rotate or tear.

My rivet nut is spinning when I try to tighten a bolt — what went wrong?

Three common causes: (1) the hole was drilled oversize, (2) the hole has a smooth (over-polished) wall and the knurls aren’t biting, or (3) the rivet nut wasn’t fully set during installation, leaving the body uncollapsed. The first two are unfixable post-install — you need to drill fresh and use a new rivet nut, or step up to a larger size. The third can be fixed by re-setting the rivet nut with a proper installation tool.

Why does the IKF series have multiple grip ranges per size?

Each IKF size is offered in short grip and long grip versions to match different sheet thicknesses. Short grip (0.027"-0.165" for 1/4-20, etc.) is for typical sheet metal. Long grip (0.165"-0.260", etc.) is for thicker panels or stacks. Picking the wrong grip range — either too short or too long — prevents the rivet nut from setting properly. See our Rivet Nut Selection Guide for the full grip-range chart.

Related Resources

• Rivet Nut Selection Guide — choosing between IKF and ISR series, materials, and grip ranges
• Rivet Nut Tool Selection Guide — hand, pneumatic, and cordless rivet nut tool comparison
• How to Install a Rivet Nut — step-by-step installation guide with common pitfalls
• Shop Rivet Nuts (IKF & ISR)
• Shop Drill Bits (Triumph T1HD+ & T9FHD)
• Shop All Rivets & Inserts