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Rivet Size Calculator

Use this rivet size calculator to determine the recommended pop or blind rivet size for your specified application.

Clear
Rivet diameter, by the 3T rule0.189 inthree times the thickness — the aircraft convention
By Unwin’s rule0.0697 in1.4 × √thickness in mm — the boilermaker’s rule
Total grip length0.063 inthe stack being joined
Rivet length needed0.3443 ingrip plus 1.5 diameters to form the shop head
Minimum edge distance0.375 intwo diameters
Minimum pitch0.5625 inthree diameters between rivets
Drill size0.1913 inabout 2% over the rivet, so it enters but fills
Shear area per rivet0.02761 in²
Single-shear capacity at 25 ksi690 lbtypical for annealed aluminium rivets

The formula

countersink depth = (Dcs − Dhole) ÷ (2 tan(angle ÷ 2))

Four hole problems, one page

A countersink’s depth follows from simple trigonometry: the cone narrows from the countersink diameter to the hole diameter, and how fast depends on the half angle. Note that 82° is the imperial standard for flat-head screws while metric uses 90° — mixing them leaves the head either proud or sunk.

True position is the one people get wrong most often. GD&T expresses it as a diameter, so the deviation is twice the radial error: being 0.003 out in x and 0.004 in y is a 0.005 radial error but a 0.010 true position deviation.

The clearance and rivet figures are conventions rather than laws, but they are the conventions drawings assume: 1.5 diameters to an edge, 3 diameters between fasteners.