Tonga
| Codes | ||
|---|---|---|
| Code | Value | Notes |
| Alpha-2 | TO | Alpha-2 code from ISO 3166-1 |
| Alpha-3 | TON | Alpha-3 code from ISO 3166-1 |
| Numeric | 776 | Numeric code from ISO 3166-1 |
| ITU | TON | Codes assigned by the International Telecommunications Union |
| FIPS | TN | Codes from the U.S. standard FIPS PUB 10-4 |
| IOC | TGA | Codes assigned by the International Olympics Committee |
| FIFA | TGA | Codes assigned by the Fédération Internationale de Football Association |
| DS | Distinguishing signs of vehicles in international traffic | |
| WMO | TO | Country abbreviations used in weather reports from the World Meteorological Organization |
| GAUL | 245 | Global Administrative Unit Layers from the Food and Agriculture Organization |
| MARC | to | MAchine-Readable Cataloging codes from the Library of Congress |
| DIAL | 676 | Country code from ITU-T recommendation E.164 (international dialing code) |
| TLD | .to | Country code Top Level Domain |