Riveting is a set of proportions. Once the thickness of the material is known, the diameter of the rivet, the length of the shank, the size of the hole, how far the hole sits from the edge and how far the rivets sit from each other all follow from published multiples of that thickness and of the rivet diameter. This rivet size calculator works all of them from the thicknesses you enter, and lets you change every multiplier to match the specification you are actually building to.
Arb Digital publishes free calculators for people who make things. The default multipliers on this page are the general figures published by the FAA in Advisory Circular 43.13-1B, and they are stated as defaults rather than as an authority. A drawing, a process specification or a fastener manufacturer's data sheet overrides them every time, and on any structural or airworthiness-significant joint it is that document, not this page, that governs.
What This Rivet Size Calculator Does
Enter the two sheet thicknesses and any extra grip from doublers or sealant, and the calculator picks a rivet diameter from the thickness rule, then works out everything downstream of it. The rivet length is the grip plus the shank allowance that gets upset into the formed head, rounded up to the next sixteenth of an inch, which is how solid rivets are actually stocked. The hole diameter adds the clearance you specify. Edge distance and pitch come from the multipliers.
It also reports the minimum dimensions the formed head should reach — a diameter of one and a half times the shank and a height of half the shank, in the standard proportions — because a driven rivet is inspected on the shop head rather than on the manufactured one. And it counts how many rivets a row of your joint length holds once the edge distances at each end are taken out.
What it does not do is design a joint. How many rivets a load needs, whether the rivet fails in shear before the sheet fails in bearing, and whether the joint tears through the net section are strength questions requiring allowables for the specific rivet alloy and the specific sheet alloy, applied with the correct safety factors. This page publishes none of those allowables, because a strength figure typed from memory is worse than no figure at all.
How to Use It
- Enter the thickness of both sheets. The diameter rule uses the thicker one; the grip uses the sum of both plus any extra.
- Adjust the diameter rule if your specification uses a different multiple, or enter a manual diameter to size everything around a rivet you already have.
- Set the edge distance and pitch multipliers from your drawing or specification. The defaults are general figures, not requirements.
- Set the hole clearance. For solid rivets it is small; for blind rivets, use the hole size the fastener manufacturer specifies rather than a clearance rule.
- Enter a joint length to get the number of rivets that fit in a row at the pitch you have chosen.
The Formula and How It Is Calculated
Diameter. D = k × tmax, with k defaulting to 3 and tmax the thicker of the two sheets. The result is then matched to the nearest standard rivet diameter at or above it, from the common inch series of 3/32, 1/8, 5/32, 3/16, 1/4 and 5/16.
Length. The grip is the total thickness of everything being joined. Rivet length = grip + h × D, where h defaults to 1.5 for the shank that becomes the formed head. The figure is rounded up to the next sixteenth of an inch when working in inches, because that is how rivets are supplied.
Hole, edge and pitch. Hole diameter = D + clearance. Minimum edge distance = e × D. Pitch along a row = p × D. Transverse pitch between rows = g × the rivet pitch.
Worked example with the defaults: sheets of 0.040 in and 0.032 in. The thicker is 0.040, so 3 × 0.040 = 0.120 in, which rounds up to a 1/8 in rivet. The grip is 0.072 in, so the length needed is 0.072 + 1.5 × 0.125 = 0.2595 in, rounded up to 5/16 in. The hole is 0.125 + 0.003 = 0.128 in. Edge distance is 2.5 × 0.125 = 0.3125 in and pitch is 4 × 0.125 = 0.500 in, giving a transverse pitch of 0.375 in. A 12 in row, less an edge distance at each end, holds 23 rivets at that pitch.
Why Edge Distance Is the Rule People Break
Edge distance is the single dimension that most often decides whether a riveted joint holds or unzips, and it is the one most often shortened to make a part fit. Set a rivet too close to the edge and the material between the hole and the edge shears out as a plug under load — a failure that happens well below the rivet's own shear strength and gives no warning. It also makes the joint far more sensitive to a hole that is drilled slightly off position.
Going the other way is not free either. Too much edge distance leaves an unsupported flange that can buckle or peel away between rivets, and on a skin it invites the sheet to lift. The published guidance gives a working band rather than a minimum for that reason, and the sensible practice is to land in the middle of it rather than at either end.
The same logic applies to pitch. Too tight and the holes weaken the net section of the sheet more than the extra rivets add — a row of holes at close pitch is a perforated line. Too loose and the sheet buckles or gapes between fasteners, which on a pressurised or sealed joint means a leak. Our clearance hole calculator covers the equivalent hole sizing question for threaded fasteners, and the bolt circle calculator gives coordinates when the pattern is circular rather than a row.
Rivet Length Is Where the Job Goes Wrong
Diameter is usually chosen correctly and length usually is not. Too short a rivet leaves a formed head that does not reach the required diameter, so it has too little bearing area on the sheet and will pull through. Too long and the shank buckles sideways as it is driven, producing a bent rivet inside the hole and a head that is wide but shallow.
Because the tolerance is narrow, the standard practice is to check the driven head rather than trust the calculation: the formed head should reach about one and a half diameters across and half a diameter high. This calculator reports both figures so you have something to gauge against. If the head is short, the rivet was short. If it is wide and flat, the rivet was long or was over-driven.
Grip range is also why blind rivets are specified differently. A blind rivet is sold for a stated grip range rather than a single length, and using one outside that range gives an incorrectly formed blind head that cannot be inspected because it is on the far side. For those, the manufacturer's grip table and hole size replace everything on this page.
What Decides Whether the Joint Is Strong Enough
Geometry gets you a valid rivet pattern; it does not get you a joint that carries load. A riveted joint has several independent failure modes and the design has to check all of them: shear across the rivet, bearing of the rivet against the hole wall in the sheet, tension across the net section between holes, and shear-out of the material between the hole and the free edge. Which one governs depends on the ratio of rivet diameter to sheet thickness, and it changes as those two are varied.
Each of those checks needs allowable stresses for the specific rivet alloy and the specific sheet alloy and temper, applied with the safety factors the governing specification requires. Those numbers live in the structural design manual or specification for the work, and on aircraft structure they carry airworthiness consequences. Our shear stress calculator and factor of safety calculator handle the general arithmetic once you have the allowables, and the bolt torque calculator covers the equivalent question for a bolted joint.
The general practices this page's defaults come from are published free by the FAA as AC 43.13-1B, Acceptable Methods, Techniques, and Practices — Aircraft Inspection and Repair, whose chapter on metal structure covers rivet selection, spacing and inspection in detail. Aerospace fastener dimensional standards are published through SAE International, and the broader industrial fastener standards are developed through ANSI-accredited committees. Work to the document your job is governed by.
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SEO Services Web Design ServicesCommon Mistakes to Avoid
- Sizing the rivet from the thinner sheet. The diameter rule uses the thickest sheet in the stack; the grip uses the total of everything being joined.
- Shortening edge distance to make a part fit. Material between the hole and the edge shears out as a plug well below the rivet's own strength, and it fails without warning.
- Using a clearance rule for a blind rivet. Blind rivets have a specified hole size and a specified grip range from the manufacturer, and neither is a multiple of the shank.
- Judging a driven rivet by the manufactured head. The formed head is what shows whether the length and the driving were right, and it should reach about 1.5 diameters across and half a diameter high.
- Treating a valid spacing pattern as a strong joint. Shear, bearing, net-section tension and shear-out all have to be checked with real allowables before a joint is a design.
Related Free Tools From Arb Digital
Size holes for threaded fasteners with the clearance hole calculator, work bolted joints with the bolt torque calculator, lay out circular patterns with the bolt circle calculator, develop sheet metal blanks with the bend allowance calculator, and work punching loads with the punch force calculator. Browse the full free online tools hub, or contact us if a calculator you need is missing.
Frequently Asked Questions
A common general rule is a diameter of about three times the thickness of the thickest sheet being joined, rounded up to the next standard rivet size. That is a starting point published as general practice, not a requirement — your drawing or specification governs.
Long enough for the total grip plus roughly one and a half diameters of shank to form the shop head, rounded up to the next sixteenth of an inch. Too short and the formed head is undersized; too long and the shank buckles as it is driven.
General practice puts it at no less than twice the rivet diameter, with around two and a half diameters typical. Closer than that and the material between the hole and the edge can shear out as a plug well below the rivet's own strength.
Pitch along a row is commonly four to six diameters, with three usually treated as a minimum. Too tight and the line of holes weakens the sheet more than the extra rivets help; too loose and the sheet can buckle or gape between fasteners.
For a solid rivet, the nominal diameter plus a small clearance, which this page takes as an input. For a blind rivet, use the hole size the manufacturer specifies for that fastener rather than applying a clearance rule.
By the formed head, not the manufactured one. In the standard proportions it should reach about one and a half diameters across and half a diameter high. A short head means a short rivet; a wide flat head means a long or over-driven one.
That is a strength calculation, not a spacing one, and this page does not answer it. It requires allowable shear and bearing stresses for the specific rivet and sheet alloys, checks on net-section tension and shear-out, and the safety factors your specification requires.
This page applies published general proportions to inputs you supply, for planning and education only. The default multipliers are general practice figures and are not a specification. It publishes no strength allowables and it designs no joint. Fastener selection, spacing and joint strength must follow the governing drawing, process specification or structural design manual, and on aircraft or other regulated structure the work must be carried out and approved by appropriately certified personnel.
