How it works
How the systems line up
All three systems describe the same mouth from the same starting point — the midline — but count in different directions. FDI splits the mouth into quadrants 1 (upper right), 2 (upper left), 3 (lower left), and 4 (lower right), then numbers teeth 1–8 from the central incisor to the third molar. Universal ignores quadrants and simply counts 1–32 around the arches. Palmer keeps the quadrant idea but draws it as a corner bracket against the tooth number — 8┐ for the upper right, ┌8 for the upper left, └8 for the lower left, and 8┘ for the lower right — the corner symbols you will see on older charts and orthodontic records.
Reading the answer
The converter also spells out the tooth in words — jaw, side, and tooth type — which is the safest way to double-check a referral letter or a chart entry before treatment begins.
Worked example
FDI 36: quadrant 3 (lower left), tooth 6 (first molar). In Universal numbering the lower left first molar is 19, and in Palmer it is LL6 — written with its corner bracket as └6. So FDI 36 = Universal 19 = Palmer LL6, the lower left first molar.
Universal 8 is the upper right central incisor: FDI 11, Palmer UR1.
Frequently asked questions
What are the three tooth numbering systems?
FDI notation (ISO 3950) uses two digits: quadrant 1-4 plus tooth 1-8 from the midline. The Universal system (used by the ADA in the US) numbers permanent teeth 1-32 starting at the upper right third molar. Palmer notation combines a quadrant bracket symbol with a number 1-8 from the midline, and is still common in orthodontics and UK charting.
How do I type Palmer notation on a keyboard?
Type the quadrant letters followed by the tooth number: UR, UL, LL, or LR and then 1-8. For example, LL6 is the lower left first molar — FDI 36, Universal 19.
Does this converter cover baby (primary) teeth?
Not yet — it covers the 32 permanent teeth. Primary teeth use letters in the Universal system (A-T) and quadrant numbers 5-8 in FDI; those follow the same quadrant logic if you need to work them out by hand.
Which upper tooth is Universal number 1?
Universal 1 is the upper right third molar (wisdom tooth) — FDI 18, Palmer UR8. Numbering then runs across the upper arch to 16 (upper left third molar), drops to 17 (lower left third molar), and finishes at 32 (lower right third molar).
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