A size 4 rivet refers to a rivet with a diameter of 4/32 inch (1/8 inch).
Rivet sizes are usually given in 32nds of an inch for diameter.
So, size 4 indicates the thickness of the rivet shank used for joining materials.

What is a size 4 rivet?

A size 4 rivet refers to a rivet whose diameter is 4/32 inch, following the standard rivet sizing system used especially in aviation and sheet metal work.

Meaning of “Size 4 Rivet”

Rivet sizes are usually expressed in 32nds of an inch (for diameter)
So, a size 4 rivet means:

👉 In metric:

≈ 3.18 mm diameter

Rivet Size Format

Rivets are often written like:

4-6 rivet

This means:

4 → diameter = 4/32 inch (1/8 inch)
6 → length = 6/16 inch (3/8 inch)

Key Dimensions of Size 4 Rivet

Diameter: 1/8 inch (3.18 mm)
Typical lengths: Vary (e.g., 4-4, 4-6, 4-8, etc.)
Head types: Snap head, countersunk head, etc.

Why Size Matters

The diameter of a rivet (like size 4) is chosen based on:

Thickness of materials being joined
Required strength
Load conditions

👉 A common rule:

Rivet diameter ≈ 3 × thickness of the sheet

Applications of Size 4 Rivets

Aircraft sheet metal structures
Light structural joints
Automotive panels
General fabrication work

Summary

A size 4 rivet is not a “type”, but a dimension classification—it simply tells you the thickness (diameter) of the rivet, which directly affects its strength and load-bearing capacity.