Rivet Nut Size Chart & Grip Range Guide
A practical rivet nut size chart: M3–M12 body and hole diameters, grip range against sheet thickness, and how to stop rivet nuts spinning out. Written for hardware distributors and B2B buyers.
Rivet Nut Size Chart & Grip Range Guide
Most failed rivet nuts are not a tool problem — they are a size problem. This is the thread / hole / grip reference we use when quoting rivet nut inserts for distributors, and the setting rules that keep inserts from spinning out.
By Alisa Xu, Product Manager, Ningbo Torchmark Hardware Co., Ltd. · LinkedIn · Reviewed against TORCHMARK production and sample data
A rivet nut — also called a nut insert, rivnut or blind nut — is set into a pre-drilled hole in thin sheet metal and collapses from the back as you tighten the tool, clamping the sheet between the nut head and a formed bulge. The thread it leaves behind lets a bolt be fitted from one accessible side and, unlike a self-tapping screw, be removed and refitted many times. That is why rivet nuts are standard in automotive repair, HVAC ducting, electrical enclosures, trailers and appliance panels.
The catch is that three numbers have to line up: the thread size (which sets the bolt), the hole / body diameter (which sets the drill) and the grip range (which must match the panel thickness). Get any one wrong and the insert is loose before it is even loaded. This guide gives the reference table and the setting rules for the metric range our factory supplies.
The rivet nut size chart (metric)
Use this table to pick the insert and the drill. The hole diameter should sit just above the nut body — roughly +0.1 to +0.3 mm — so the insert enters freely but does not rattle in the hole.
Thread | Nut body Ø (mm) | Drill / hole Ø (mm)* | Typical grip range (mm) | Typical use |
|---|---|---|---|---|
M3 | 4.8–5.0 | 5.0 | 0.5–3.0 | Light panels, electronics, trim |
M4 | 5.9–6.1 | 6.0 | 0.5–4.0 | Cabinets, small housings |
M5 | 6.8–7.0 | 7.0 | 0.5–4.5 | General sheet metal |
M6 | 8.8–9.0 | 9.0 | 0.5–5.0 | Automotive, HVAC brackets |
M8 | 10.8–11.0 | 11.0 | 1.0–6.0 | Structural panels, trailers |
M10 | 12.8–13.0 | 13.0 | 1.0–6.5 | Heavy brackets, equipment |
M12 | 14.8–15.0 | 15.0–16.0 | 1.5–7.0 | High-load fixing points |
* Figures are typical for standard carbon-steel and stainless rivet nuts. Body diameter, hole size and grip range vary with head style (flat, small, countersunk) and shank style (round, knurled, hex), and between manufacturers' tooling. Treat this as a reference and confirm the exact values on the quotation for the grade you buy.
A long-handle manual tool like the TORCHMARK LR-HR-09 gives the leverage to set steel and stainless inserts cleanly — dimensions are 37 cm closed, 50 cm open span.
How to read the grip range against your panel
The grip range is the range of total material thickness the insert can clamp. It is not the same as the hole depth, and it is not the same as the bolt length. Measure the panel or stack of panels the fastener passes through, then choose the insert whose grip range contains that number:
- Panel thicker than the grip range — the insert cannot collapse far enough. It sits proud, the thread is short and the joint fails early. Step up to a longer insert, or specify a variant with a wider grip range.
- Panel thinner than the grip range — the insert collapses on itself before it grips. Fit a spacer washer, or choose a closed-end / short-grip variant.
- Panel right at the edge of the range — test on an offcut first. Tooling tolerance means the nominal figure is a guide, not a guarantee.
The same logic applies to blind rivets (pop rivets): their grip range, not their diameter, decides whether the rivet clamps the joint or hangs loose. A 4.8 mm rivet still has several grip variants.
Metric or inch threads — what to stock
Metric coarse is the default for most of Europe, Asia and much of HVAC and industrial equipment. Inch UNC / UNF threads remain common in North American automotive and appliance work — #6-32, #8-32, #10-24, #10-32, 1/4"-20, 5/16"-18, 3/8"-16. A distributor serving both markets needs both, and the tool's mandrels must match: a metric mandrel will not set an inch insert. This is the single reason we configure the LR-HR-09 kit per order rather than shipping one fixed mandrel set.
Choosing the rivet nut material
Material | Grade | Best for | Sourcing note |
|---|---|---|---|
Carbon steel, zinc-plated | General fastening grade | General sheet metal, cabinets, value assemblies | Highest volume, lowest cost line |
Stainless A2 (304) | 304 | Outdoor, damp, general corrosion | Needs the long-handle tool for clean setting |
Stainless A4 (316) | 316 | Marine, chemical, food equipment | Highest corrosion resistance |
Aluminium | — | Light load, soft or thin panels | Easiest to set; avoid high-torque joints |
Two practical rules we pass on to every buyer: stainless inserts need noticeably more setting force (the installation torque runs roughly a third higher than aluminium), which is why the long-handle tool matters; and soft or thin panels call for a slightly smaller hole, while a steel panel wants a slightly larger one, because the base material's own give changes how the bulge forms.
Head and shank styles — where they matter
- Flat head — the general-purpose default; sits on the panel face.
- Small / low-profile head — minimal protrusion where clearance is tight.
- Countersunk head — flush fit into a countersunk hole for a flat surface.
- Round shank — relies on friction; fine for light duty.
- Knurled shank — the knurl bites into the panel and resists rotation under torque. The right choice where a bolt will be repeatedly removed and refitted.
- Hex / square shank — the strongest anti-rotation option; needs the matching shaped hole.
The four failures we see, and their fixes
- Insert spins when the bolt is tightened. Oversized hole or an insert that was never set fully. A hole more than about 0.2 mm oversize can cut anti-torque resistance by around 20%. Fix: correct drill size, full set, and a knurled or hex shank for high-torque joints.
- Panel bulges or cracks. Too much setting stroke, or too large a hole combined with a thin panel. Fix: reduce the stroke, check the grip range and support the panel during setting.
- Insert sits proud / thread is short. Grip range too small for the panel. Fix: longer insert or a wider-grip variant.
- Thread cross-threaded or damaged on the first bolt. Bolt forced into a slightly mis-set insert. Fix: set fully and squarely, and start the bolt by hand before applying torque.
Setting a rivet nut cleanly — the six steps
- Drill the correct hole for the nut body; deburr both faces.
- Check the panel thickness against the insert grip range.
- Thread the insert onto the correct mandrel; set the tool stroke per the insert size.
- Insert the nut into the hole and hold the tool square to the panel.
- Squeeze the handles through the full stroke — do not stop halfway.
- Reverse the tool to release; confirm the insert is flush, square and cannot be turned by hand.
Stocking checklist for distributors
- Cover the thread ladder, not one size. Stock M3–M12 (and the inch equivalents for North America) so any panel your trade encounters can be served.
- Carry both materials. Zinc-plated steel as the volume line, A2/A4 stainless for the corrosion-critical end.
- Match the tool to the threads. A kit with interchangeable mandrels avoids dead stock and lets one box serve the whole ladder.
- Keep blind rivets alongside. Where a rivet nut gun is impractical (light ducting, louvres), a pop rivet of the matching grip range finishes the job.
Sourcing rivet nut tools and inserts for resale? Send the thread sizes, panel thickness and material you sell most. We confirm the mandrel set, insert grade and grip range, and quote the tool and fasteners together in one shipment.Request a quote
Frequently asked questions
What size hole do I drill for an M6 rivet nut?
A standard M6 rivet nut has a body diameter of about 8.8–9.0 mm and calls for a drill hole of around 9.0 mm — just above the body so the insert enters freely without being loose. Confirm against the exact grade and head style you buy.
How do I choose the right grip range?
Match it to the total panel thickness: M3 about 0.5–3.0 mm, M4 0.5–4.0 mm, M5 0.5–4.5 mm, M6 0.5–5.0 mm, M8 1.0–6.0 mm, M10 1.0–6.5 mm, M12 1.5–7.0 mm. Too thick and the insert cannot collapse; too thin and it collapses before gripping.
Why does my rivet nut spin when I tighten the bolt?
An oversized hole or an insert that was not set fully, so it never gripped the sheet. A hole more than about 0.2 mm oversize can cut anti-torque by around 20%. Use the correct drill size, set fully, and choose a knurled or hex shank for high-torque joints.
Can one tool set both steel and stainless rivet nuts?
Yes, if it has enough leverage. Stainless installs at roughly a third more torque than aluminium, so a long-handle tool such as the 14-inch LR-HR-09 sets aluminium, steel and stainless from one unit — a compact tool often cannot.
Metric or inch rivet nuts — which should I stock?
Metric coarse for most of Europe, Asia and industrial equipment; inch UNC/UNF for much North American automotive and appliance work. Serving both markets means stocking both thread families and matching mandrels.
Related reading
See the full tool and fastener range on our hand rivet nut tools & fasteners page — the 14-inch LR-HR-09 kit, rivet nut inserts, TR-RIV blind rivets and TR-STS threaded stud bolts.
Also in the TORCHMARK riveting and fastening series: our rivet nut gun buying guide for hardware distributors, and for the wider range see the PVC/PPR pipe tools and hydraulic crimping tools.
Explore the full TORCHMARK tool range Flaring, drain cleaning, riveting, lubrication, crimping and pipe tools — product pages and B2B buying guides in one place.Go to Tools Hub →