| Rank | Country | Suffrage |
| Southern Ocean | void |
188 | Spain | 18 years of age; universal |
| Spratly Islands | void |
189 | Sri Lanka | 18 years of age; universal |
222 | Sudan | 17 years of age; universal |
190 | Suriname | 18 years of age; universal |
| Svalbard | void |
191 | Swaziland | 18 years of age |
192 | Sweden | 18 years of age; universal |
193 | Switzerland | 18 years of age; universal |
194 | Syria | 18 years of age; universal |
19 | Taiwan | 20 years of age; universal |
195 | Tajikistan | 18 years of age; universal |
196 | Tanzania | 18 years of age; universal |
197 | Thailand | 18 years of age; universal and compulsory |
223 | Timor-Leste | 17 years of age; universal |
198 | Togo | 18 years of age; universal |
12 | Tokelau | 21 years of age; universal |
13 | Tonga | 21 years of age; universal |
199 | Trinidad and Tobago | 18 years of age; universal |
200 | Tunisia | 18 years of age; universal except for active government security forces (including the police and the military), people with mental disabilities, people who have served more than three months in prison (criminal cases only), and people given a suspended sentence of more than six months |
201 | Turkey | 18 years of age; universal |