How to Choose the Right Rivet Size
Quick answer: Choosing the right rivet requires matching two dimensions: cap diameter (proportionate to the leather weight and aesthetically appropriate for the application) and post length (which must match the combined thickness of the layers being joined). Assemble the actual leather layers and test nearby post lengths on matching offcuts before setting the finished piece. Test on scrap leather before setting on the final piece — rivets cannot be undone without damaging the leather.
Rivets come in different cap diameters and post lengths, and choosing the right combination for the leather and application matters more than it might seem. The wrong post length produces a poorly set rivet that either will not set at all or sits untidily in the leather. The wrong cap size can look out of proportion or leave the leather around the hole unsupported. This guide explains how to think about rivet sizing.
The two dimensions that matter
Every rivet has two dimensions to consider: cap diameter (the size of the visible top) and post length (the shank that passes through the leather and is set on the back side).
Cap diameter is primarily an aesthetic and practical choice. A larger cap sits over a wider area of leather and is proportionate to heavier, thicker work. A smaller cap is appropriate for lighter leather and finer applications. The hole punched for the rivet must be sized to match the post — not the cap — so cap diameter does not directly affect hole size.
Post length must match the combined thickness of the leather being joined. The post needs to pass through all layers of leather fully, and enough post should emerge on the back side to set cleanly. Too short and there is insufficient material to set properly; the rivet will be loose or fail to secure. Too long and the excess post needs to be managed during setting, which can produce an untidy back, and the cap may not seat flush against the leather surface.
Measuring for the right post length
Assemble the leather layers exactly as they will sit in the finished piece, including any lining, skiving and adhesive. Test the available post lengths on offcuts from that construction. Leather compresses during setting, so a simple fixed allowance does not predict the result reliably.
A post that is too short will not engage securely. A post that is too long can bend, set loosely or leave the fitting distorted. Choose the length that produces a clean, firm set in the actual compressed leather rather than automatically adding 1–2mm.
Post diameter and hole sizing
The post must fit the punched hole cleanly — the post should slide through without excessive play but without requiring force. A post that is loose in the hole can rotate or sit off-centre before setting. A post that has to be forced risks distorting the leather around the hole.
Punch the hole with a drive punch sized to match the post diameter. Most drive punch sets include the common diameters needed for standard rivet posts. If in doubt, test the fit of the post in a hole punched in scrap leather from the same piece before committing to the final hole on the workpiece.
Single cap vs double cap
Single cap rivets have a decorative cap on the face side and a plain, flared finish on the back. They are used where the back of the piece is not visible.
Double cap rivets have a decorative cap on both sides. Both the face and the back have a clean, finished appearance, which suits pieces where both sides are visible — bag straps, luggage tags, loop attachments, and similar applications.
Using the right setter
Every rivet type and size has a corresponding setter — a tool that fits the cap profile and is used to drive and shape the rivet during setting. Using a setter that does not match the cap diameter or profile will damage the cap surface or produce an off-centre, untidy set.
Keep the cap setter for the specific rivets you are working with. Do not use a setter designed for a different size or style of rivet, even if it appears similar.
Testing on scrap
Before setting any rivet on a finished piece, set one in scrap leather of the same combined thickness. This confirms that the post length is correct, that the hole size is right, and that the setter is producing a clean result. Rivets cannot be undone without damaging the leather — testing first costs thirty seconds and prevents a permanent mistake.
Frequently asked questions
How do I know what size rivet to use for leather?
Two dimensions matter: cap diameter and post length. Cap diameter is primarily a practical and design choice. Post length must suit the complete leather construction after compression. Assemble the real layers, including lining, skiving and adhesive, then test the nearby post lengths on matching offcuts. Do not rely on a universal 1–2mm allowance.
What is the difference between single cap and double cap rivets?
Single cap rivets have a decorative domed cap on the face side and a plain, folded finish on the back. Double cap rivets have a decorative cap on both the face and the back. Use double cap rivets where both sides of the leather are visible — on bag straps, luggage tags, and loop attachments. Use single cap where the back of the piece will not be seen.
How long should rivet posts be?
Long enough to engage and set securely without excess post bending or leaving the fitting loose. Because leather compresses and rivet constructions vary, test the nearby sizes on matching offcuts. Do not rely on a universal 1–2mm allowance.
How do you set leather rivets correctly?
Use a hole punch sized to match the post diameter, pass the post through cleanly, place the cap setter over the cap, and strike with a mallet firmly. The post material spreads or folds on the back side to lock the rivet. Always use the setter designed for the specific rivet size — a mismatched setter will damage the cap face or produce an off-centre set.
