Tonga
| Year | Electoral system family | Electoral system for national legislature | Number of tiers | Legislative size (directly elected) | Legislative size (voting members) | Electoral system for the president |
|---|---|---|---|---|---|---|
| 2021 | Plurality/Majority | FPTP | 1 | 17 | 26 | Not applicable |
| 2017 | Plurality/Majority | FPTP | 1 | 17 | 26 | Not applicable |
| 2014 | Plurality/Majority | FPTP | 1 | 17 | 26 | Not applicable |
| 2010 | Plurality/Majority | FPTP | 1 | 17 | 26 | Not applicable |
| 2008 | Plurality/Majority | BV | 1 | 9 | 30 | Not applicable |
| 2005 | Plurality/Majority | BV | 1 | 9 | 30 | Not applicable |
| 1999 | Plurality/Majority | BV | 1 | 9 | 30 | Not applicable |
| 1996 | Plurality/Majority | BV | 1 | 9 | 30 | Not applicable |
| 1993 | Plurality/Majority | BV | 1 | 9 | 30 | Not applicable |
