Free dental reference tool

FDI to Universal tooth number converter

The FDI two-digit system (ISO 3950) is the international standard; the Universal system is used across the United States. Choose an FDI number below and this tool highlights the tooth and shows its Universal number and Palmer designation. For example, FDI 26 is Universal 14 — the upper left first molar.

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Select any tooth to convert its number.

Full conversion table

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Upper right

Universal	FDI	Palmer
8	11	1
7	12	2
6	13	3
5	14	4
4	15	5
3	16	6
2	17	7
1	18	8

Upper left

Universal	FDI	Palmer
9	21	1
10	22	2
11	23	3
12	24	4
13	25	5
14	26	6
15	27	7
16	28	8

Lower left

Universal	FDI	Palmer
24	31	1
23	32	2
22	33	3
21	34	4
20	35	5
19	36	6
18	37	7
17	38	8

Lower right

Universal	FDI	Palmer
25	41	1
26	42	2
27	43	3
28	44	4
29	45	5
30	46	6
31	47	7
32	48	8

How FDI numbers map to Universal numbers

In FDI notation the first digit is the quadrant — 1 upper right, 2 upper left, 3 lower left, 4 lower right for permanent teeth (5–8 for primary teeth) — and the second digit is the position from the midline, 1 for the central incisor out to 8 for the third molar. The Universal system instead numbers permanent teeth 1–32 in a single sweep. Because the two systems count in different directions, converting by hand is error-prone; this tool does the mapping for every permanent and primary tooth.

Need the full picture across all three systems? Open the full tooth numbering chart.