Tooth numbering converter

FDI notation, standardised as ISO 3950, uses two digits. The first is the quadrant — 1 upper right, 2 upper left, 3 lower left, 4 lower right for permanent teeth, and 5 to 8 in the same order for primary teeth. The second digit counts outward from the midline, 1 to 8. So 16 is the upper right first molar. It is the system used across Europe, Turkey and most of the world.

The Universal system, used mainly in the United States, numbers permanent teeth 1 to 32 in one continuous sweep: 1 is the upper right third molar, 16 the upper left third molar, 17 the lower left third molar, and 32 the lower right third molar. Primary teeth use letters A to T on the same path.

Palmer notation gives the tooth its position number, 1 to 8, together with a bracket showing which quadrant it belongs to as you face the patient. Upper right teeth take a bracket opening to the upper left, and so on around the mouth. Primary teeth use letters A to E instead of numbers. It is still common in orthodontics and in the UK.

Because the systems overlap numerically. In FDI, 16 is the upper right first molar. In Universal, 16 is the upper left third molar. That is why this converter asks which system your number is in rather than guessing — a wrong guess would give you the wrong tooth.

Primary dentition has 20 teeth rather than 32, with no premolars. FDI uses quadrants 5 to 8 with positions 1 to 5, Universal uses letters A to T, and Palmer uses letters A to E with the same quadrant brackets. Switch the toggle above to work in primary numbering.