What this calculator does
Bolton tooth-size ratio works out compares upper and lower tooth widths to flag a size mismatch before orthodontic treatment. Enter your own figures above and the answer updates as you type: nothing is fixed in the code, so the result reflects exactly the numbers you supply.
The formula this calculator evaluates is printed under the tool and explained below, so you can check the working by hand or reuse it in a spreadsheet.
The formula
The inputs explained
| Field | What to enter |
|---|---|
| Mandibular anterior width sum (6 teeth) (mm) | A number, measured in mm. Starts at 36.8. |
| Maxillary anterior width sum (6 teeth) (mm) | A number, measured in mm. Starts at 47.7. |
| Mandibular total width sum (12 teeth) (mm) | A number, measured in mm. Starts at 104.9. |
| Maxillary total width sum (12 teeth) (mm) | A number, measured in mm. Starts at 114.9. |
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How the answer changes with mandibular anterior width sum (6 teeth)
Every other input is held at the calculator’s starting values while mandibular anterior width sum (6 teeth) varies. Select any row to load that scenario into the calculator.
| Mandibular anterior width sum (6 teeth) (mm) | Anterior ratio | Overall ratio | Standard means (Bolton, 1958) |
|---|---|---|---|
| 18.4 | 38.6% | 91.3% | Anterior 77.2% · Overall 91.3% |
| 27.6 | 57.9% | 91.3% | Anterior 77.2% · Overall 91.3% |
| 36.8 | 77.1% | 91.3% | Anterior 77.2% · Overall 91.3% |
| 55.2 | 115.7% | 91.3% | Anterior 77.2% · Overall 91.3% |
| 73.6 | 154.3% | 91.3% | Anterior 77.2% · Overall 91.3% |
| 110 | 230.6% | 91.3% | Anterior 77.2% · Overall 91.3% |