Solid rivet length calculator for aircraft and sheet metal joints. It finds length from grip plus 1.5D, the stock rivet to order, drill size, edge distance, pitch and rivet counts.
Measure the full stack the rivet passes through, then pick the rivet.
Shop Head, Alloy and Load
Rivet Cross-Section
Rivet Length Chart, 1/8 in
| Stock Length | Length in mm | Ideal Grip (1.5D Tail) | Max Grip (1.25D Tail) |
|---|---|---|---|
| 1/4 in (-4) | 6.35 mm | 0.0625 in | 0.0938 in |
| 5/16 in (-5) | 7.94 mm | 0.1250 in | 0.1563 in |
| 3/8 in (-6) | 9.53 mm | 0.1875 in | 0.2188 in |
| 7/16 in (-7) | 11.11 mm | 0.2500 in | 0.2813 in |
| 1/2 in (-8) | 12.70 mm | 0.3125 in | 0.3438 in |
| 9/16 in (-9) | 14.29 mm | 0.3750 in | 0.4063 in |
| 5/8 in (-10) | 15.88 mm | 0.4375 in | 0.4688 in |
| 11/16 in (-11) | 17.46 mm | 0.5000 in | 0.5313 in |
Step-by-Step Math
- Grip G = 0.1400 in, the full stack the shank passes through.
- Allowance = k × D = 1.5 × 0.125 in = 0.1875 in (aircraft bucktail).
- Exact length L = G + k × D = 0.1400 in + 0.1875 in = 0.3275 in.
- Longest stock rivet with a 1.25D to 1.5D tail: 5/16 in (-5) = 0.3125 in; tail = 0.3125 in - 0.1400 in = 0.1725 in = 1.38D.
- PPS 2.01 allows a 1.25D to 1.5D tail (0.1563 in to 0.1875 in); buck to at least 0.165 in wide × 0.05 in high.
- Shear = π/4 × hole² × Fsu = π/4 × (0.1285 in)² × 30,000 psi = 389 lbf per shear plane.
- Result: 0.3275 in Exact Rivet Length.
Solid Rivet Length Calculator Formula: L = G + 1.5D
A solid rivet must be as long as the stack it passes through plus 1.5 times its own diameter. The extra 1.5D is the tail that gets bucked into the shop head, so for a 1/8 in rivet through a 0.140 in stack, L = 0.140 + 1.5 × 0.125 = 0.3275 in.
L is the rivet length, G is the grip (the total thickness of every sheet the shank passes through) and D is the shank diameter. A universal-head rivet is measured from under the head, so the head itself is not part of L.
Rivets come in 1/16 in length steps, so 0.3275 in becomes a 5/16 in rivet: MS20470AD4-5. That leaves a 0.1725 in tail, or 1.38D, which is inside the accepted tail range.
Change the grip to 0.100 in and no stock length fits: 1/4 in leaves 1.20D, too short, and 5/16 in leaves 1.70D, too long. Take the 5/16 in rivet and trim 0.025 in off the tail with a rivet cutter before driving.
Bombardier's solid rivet process spec, PPS 2.01, sets the tail at 1.25 to 1.5 times the shank diameter past the material. A solid rivet length calculator should pick the stock size whose tail lands in that range, and call for trimming when none does; a tail under 1.25D cannot form a full shop head.
Solid Rivet Length Chart by Grip and Diameter
The chart gives the shortest stock length that leaves at least a 1.25D tail, with the actual tail in brackets. A tail above 1.5D means trim to 1.5D before driving.
Read across from your total grip to your rivet diameter; lengths are in sixteenths of an inch, which is also the dash number after the diameter in the part number.
| Total grip (in) | 3/32 in rivet (-3) | 1/8 in rivet (-4) | 5/32 in rivet (-5) | 3/16 in rivet (-6) |
|---|---|---|---|---|
| 0.040 | 3/16 (1.57D) | 1/4 (1.68D) | 1/4 (1.34D) | 5/16 (1.45D) |
| 0.064 | 3/16 (1.32D) | 1/4 (1.49D) | 5/16 (1.59D) | 5/16 (1.33D) |
| 0.080 | 1/4 (1.81D) | 1/4 (1.36D) | 5/16 (1.49D) | 3/8 (1.57D) |
| 0.100 | 1/4 (1.60D) | 5/16 (1.70D) | 5/16 (1.36D) | 3/8 (1.47D) |
| 0.125 | 1/4 (1.33D) | 5/16 (1.50D) | 3/8 (1.60D) | 3/8 (1.33D) |
| 0.160 | 5/16 (1.63D) | 3/8 (1.72D) | 3/8 (1.38D) | 7/16 (1.48D) |
| 0.190 | 5/16 (1.31D) | 3/8 (1.48D) | 7/16 (1.58D) | 7/16 (1.32D) |
The 1.25D to 1.5D window is only 0.25D wide, narrower than one 1/16 in length step on any rivet up to 3/16 in. That is why 11 of the 28 cells above need trimming, and why a solid rivet length calculator on small rivets reaches for the cutter so often.
Feed a solid rivet length calculator the measured grip, not the sum of nominal sheet sizes. Primer, sealant and a slightly bowed skin all add thickness, and a 0.040 in and a 0.032 in sheet that measure 0.075 in together need the length for 0.075 in, not 0.072 in.
How to Read a Rivet Part Number and Measure a Rivet
An aircraft rivet part number gives head style, alloy, diameter and length in one code. In MS20470AD4-5, MS20470 is the universal head, AD is 2117-T4 aluminum, 4 is the diameter in 32nds (4/32 = 1/8 in) and 5 is the length in 16ths (5/16 in).
Countersunk rivets such as MS20426 are measured overall, from the top of the head to the end of the shank, because the head sits inside the countersink and counts toward the grip. The same L = G + 1.5D formula works when G includes the full thickness of the countersunk sheet.
Set the countersink so the head sits flush, using the Countersink Depth Calculator for the 100° angle these rivets use. A head that sits proud or below the skin changes the grip the rivet sees.
What does mm mean on a rivet?
A metric rivet size gives diameter and then length, both in millimeters. A 3.2 × 12 mm rivet has a 3.2 mm shank and is 12 mm long; 3.2 mm is the metric equivalent of a 1/8 in rivet, which is why that size is so common on blind rivet packs.
The same formula runs in millimeters. A 3 mm solid rivet through two 2 mm sheets needs 4 + 1.5 × 3 = 8.5 mm, so a solid rivet length calculator in metric picks the nearest stock length that still leaves a 1.25D tail.
How to Calculate Rivet Diameter From Sheet Thickness
A rivet's diameter should be about 3 times the thickness of the thickest sheet in the joint. A thinner rivet shears before the sheet carries its share of load, and a much fatter one wastes weight and can bulge thin skin when it is bucked.
For a 0.040 in sheet riveted to a 0.032 in sheet, 3 × 0.040 = 0.120 in, so the next standard size up, 1/8 in, is the diameter to give a solid rivet length calculator. Size the diameter first, then work out the length, since the tail allowance depends on D.
| Thickest sheet (in) | 3 × thickness (in) | Standard rivet | Dash number |
|---|---|---|---|
| 0.016 | 0.048 | 1/16 in | -2 |
| 0.020 | 0.060 | 1/16 in | -2 |
| 0.025 | 0.075 | 3/32 in | -3 |
| 0.032 | 0.096 | 1/8 in | -4 |
| 0.040 | 0.120 | 1/8 in | -4 |
| 0.050 | 0.150 | 5/32 in | -5 |
| 0.063 | 0.189 | 3/16 in | -6 |
0.032 in is a borderline case: 3 × 0.032 = 0.096 in sits just above a 3/32 in rivet (0.094 in), so the rule rounds up to 1/8 in. Standard solid rivet sizes in inches run 1/16, 3/32, 1/8, 5/32, 3/16 and 1/4 in; common metric solid rivets run 2, 2.5, 3, 4, 5, 6 and 8 mm.
Bucked Shop Head Size and When a Rivet Is Too Long
A well-formed shop head is about 1.5D wide and 0.5D high. For a 1/8 in rivet that is 0.188 in wide and 0.063 in high, and the 1.5D tail from the length formula is sized to supply just enough metal for it.
A solid rivet length calculator that leaves a 1.70D tail supplies more metal, so the head comes out wider or taller unless the tail is trimmed.
| Rivet | Target width, 1.5D (in) | Target height, 0.5D (in) | Minimum width (in) | Minimum height (in) |
|---|---|---|---|---|
| 3/32 in (-3) | 0.141 | 0.047 | 0.122 | 0.038 |
| 1/8 in (-4) | 0.188 | 0.063 | 0.165 | 0.050 |
| 5/32 in (-5) | 0.234 | 0.078 | 0.203 | 0.062 |
| 3/16 in (-6) | 0.281 | 0.094 | 0.245 | 0.075 |
| 1/4 in (-8) | 0.375 | 0.125 | 0.325 | 0.100 |
The minimum columns are Bombardier PPS 2.01 Table 14 values for aluminum rivets other than 7050. They work out to about 1.3D wide and 0.4D high, which is why a shop head under 1.3D wide gets drilled out and replaced.
Can a rivet be too long?
Yes. Extra tail tends to bend over or clinch sideways under the bucking bar instead of upsetting straight, leaving a lopsided head. A tail of 2D or more on a 1/8 in rivet is long enough that trimming it before driving is the better choice.
A long grip causes the same trouble from the other side. When the stack is much thicker than the rivet is wide, the shank can bend inside the hole rather than swell to fill it, so thick stacks call for a larger rivet or a bolt, sized with the Bolt Length Calculator.
What Drill Size for Rivets
Drill the hole a few thousandths over the rivet's shank so it slides in but fills the hole when bucked; the same hole size sets the shear area a solid rivet length calculator uses for strength. A 1/8 in rivet takes a #30 drill (0.1285 in); a 3/16 in rivet takes a #11 (0.191 in).
| Rivet | Shank (in) | Drill | Drill size (in) | PPS 2.01 hole range (in) |
|---|---|---|---|---|
| 1/16 in (-2) | 0.0625 | #51 | 0.0670 | 0.066-0.071 |
| 3/32 in (-3) | 0.0938 | #40 | 0.0980 | 0.098-0.102 |
| 1/8 in (-4) | 0.1250 | #30 | 0.1285 | 0.128-0.133 |
| 5/32 in (-5) | 0.1563 | #21 | 0.1590 | 0.159-0.166 |
| 3/16 in (-6) | 0.1875 | #11 | 0.1910 | 0.190-0.196 |
| 1/4 in (-8) | 0.2500 | F | 0.2570 | 0.253-0.263 |
| 5/16 in (-10) | 0.3125 | O | 0.3160 | 0.317-0.323 |
| 3/8 in (-12) | 0.3750 | V | 0.3770 | 0.378-0.387 |
A rivet smaller than its hole does not belong there. A loose rivet cannot fill the hole, and the joint loses shear strength; when a hole is oversize after drilling out a bad rivet, the fix is the next rivet size up with its own drill.
The Clearance Hole Calculator covers bolt and screw holes, which use a looser fit than rivets. Rivet holes stay tight because the driven rivet must fill them completely.
Rivet Edge Distance and Pitch Formula
Keep each rivet center at least 2D from the sheet edge and at least 3D from the next rivet in the row. For a 1/8 in rivet that is 0.250 in from the edge and 0.375 in between rivets.
| Rivet | Min edge distance, 2D (in) | Edge distance, 2.5D (in) | Min pitch, 3D (in) | Pitch, 4D (in) |
|---|---|---|---|---|
| 3/32 in | 0.188 | 0.234 | 0.281 | 0.375 |
| 1/8 in | 0.250 | 0.313 | 0.375 | 0.500 |
| 5/32 in | 0.313 | 0.391 | 0.469 | 0.625 |
| 3/16 in | 0.375 | 0.469 | 0.563 | 0.750 |
| 1/4 in | 0.500 | 0.625 | 0.750 | 1.000 |
Closer than 2D to the edge, the rivet can tear out of the sheet; closer than 3D to its neighbor, the row of holes weakens the sheet like a perforated stamp. Countersunk rivets need more edge distance, because the countersink removes material near the edge.
Edge distance and pitch are measured from hole centers, so a solid rivet length calculator's diameter feeds the layout too. Mark a rivet circle on a round part with the Bolt Circle Calculator, then check the pitch against 3D.
How to Calculate the Number of Rivets Required
Divide the joint load, times a safety factor, by the shear strength of one rivet. A driven rivet fills its hole, so its shear area is the area of the drilled hole, not the nominal shank.
P is the load, SF the safety factor, dh the hole diameter and Fsu the rivet alloy's ultimate shear strength. A 1/8 in AD rivet in a #30 hole carries π/4 × 0.1285² × 30,000 = 389 lbf, so 1,000 lbf at 1.5 needs 1,500 ÷ 389 = 3.9, or 4 rivets.
| Rivet (hole) | AD, 2117-T4, 30 ksi (lbf) | D, 2017-T4, 38 ksi (lbf) | DD, 2024-T4, 41 ksi (lbf) | B, 5056, 28 ksi (lbf) | Monel, 49 ksi (lbf) |
|---|---|---|---|---|---|
| 3/32 in (0.098) | 226 | 287 | 309 | 211 | 370 |
| 1/8 in (0.1285) | 389 | 493 | 532 | 363 | 635 |
| 5/32 in (0.159) | 596 | 755 | 814 | 556 | 973 |
| 3/16 in (0.191) | 860 | 1,089 | 1,175 | 802 | 1,404 |
| 1/4 in (0.257) | 1,556 | 1,971 | 2,127 | 1,452 | 2,542 |
A solid rivet length calculator reports these values as single shear, one plane cut between two sheets. A rivet that joins three sheets, with the load in the middle sheet, is in double shear and carries twice the load, which is why double-shear joints need half the rivets.
Rivet shear is only one way a joint fails. The sheet can also tear between holes or crush at the hole, so thin sheet often limits a joint before the rivets do; a fatigue-loaded or flight-critical joint needs an engineer's check, not just a rivet count.
What safety factor should I use for structural rivets?
Use the factor your design code or drawing specifies. Aircraft structure is designed to ultimate loads that already include a 1.5 factor on limit load, so 1.5 is a common default in a solid rivet length calculator, but a hoist, trailer or machine guard may call for more.
Solid, Blind and Semi-Tubular Rivets
The three main types of rivets are solid, blind and semi-tubular. Solid rivets are bucked from both sides and are the strongest; blind or pop rivets are set from one side; semi-tubular rivets have a hollow tip that rolls over with less force.
Blind rivets are not sized with L = G + 1.5D, so a solid rivet length calculator does not apply to them.
Each blind rivet has a grip range printed by its maker, so a 3.2 × 12 mm pop rivet's grip range comes from the maker's chart, and a pop rivet length calculator simply matches your stack to that range.
How to do a solid rivet
Drill the hole to size, deburr both sides, insert the rivet, then hold a bucking bar flat on the tail while a rivet gun drives the factory head. Stop when the shop head reaches about 1.5D wide and 0.5D high, and check it against the minimums above.
Rivet heads carry alloy marks: a plain head is A, a dimple is AD, a raised dot is D and a raised double dash is DD. Check the mark against the drawing before driving, since the alloy sets the rivet's shear strength in the table above.
What Is a Solid Rivet Length Calculator?
A solid rivet length calculator finds the length of a solid rivet from the grip and shank diameter using L = G + 1.5D, then matches it to a stock length. It also gives the drill size, edge distance, pitch and rivet count that go with that rivet.
When should you use the rivet length calculator?
Use it before ordering or pulling rivets from a bin, whenever the grip changes along a joint. A skin that steps from 0.040 in to 0.064 in under a doubler needs two lengths, and picking one length for both leaves either short tails or long ones.