What is the diameter of the inner bullseye on a standard dartboard?

The diameter of the inner bullseye on a standard dartboard is 12.7 millimetres.

The inner bull, commonly called the bullseye, is the small central scoring area. In standard steel-tip darts it scores 50 points, while the surrounding outer bull scores 25 points. Together they form the board’s two concentric bull sections.

The bull is much smaller than the treble and double rings, so hitting it consistently requires precision. The inner bull’s compact size is also why measurements are normally given in millimetres rather than centimetres.

A common mistake is to quote the diameter of the outer bull or the radius of the inner bull instead. The 12.7-millimetre figure is the diameter of the inner scoring circle, not the entire central area.