Olgii's 2026 population is now estimated at 47,523. In 1979, the population of Olgii was 18,700. Olgii has grown by 1,677 in the last year, which represents a 3.66% annual change. These population values and projections come from Mongolia city census/estimate series 1979-2021 via CityPopulation official attribution, NSO Mongolia PxWeb resident population by soum/district (direct) and World Population Review Internal Projections .
| City | 2026 Pop. ↓ | Growth |
|---|---|---|
| Ulaanbaatar | 1,682,636 | 2.79% |
| Erdenet | 112,520 | 1.95% |
| Bayankhongor | 93,276 | 0.72% |
| Darkhan | 93,028 | 1.21% |
| Choibalsan | 52,102 | 2.01% |
| Moron | 51,749 | 4.05% |
| Olgii | 47,523 | 3.66% |
| Nalaikh | 40,146 | 0.62% |
| Arvaikheer | 39,257 | 2.55% |
| Khovd | 38,738 | 3.91% |
| Dalanzadgad | 36,525 | 4.83% |
| Ulaangom | 35,557 | 1.56% |
| Sainshand | 32,063 | 3.19% |
| Baganuur | 29,892 | 0.31% |
| Ondorkhaan | 25,944 | 1.47% |
| Baruun-Urt | 25,458 | 5.12% |
| Sukhbaatar | 22,124 | -0.26% |
| Tsetserleg | 22,086 | 1.13% |
| Altai | 19,205 | 1.86% |
| Zuunmod | 18,872 | 1.74% |
| Zamyn-Uud | 18,401 | -0.64% |
| Uliastai | 17,526 | 1.11% |
| Mandalgovi | 16,713 | 5.09% |
| Choir | 13,098 | 3.87% |
| Zuunkharaa | 6,520 | 1.51% |
| Khatgal | 4,780 | 5.12% |
| Bagakhangai | 4,439 | -0.09% |
| Bugant | 3,993 | 4.15% |
| Bulgan | 3,057 | 1.66% |
| Berkh | 2,914 | 4.15% |
| Khyalganat | 2,679 | -2.08% |
| Nomgon | 2,090 | 1.01% |
| Dulaankhaan | 2,068 | 2.78% |
| Orkhontuul | 1,987 | 1.38% |
| Tsagaannuur | 1,872 | 2.41% |
| Gurvanbayan | 1,086 | 2.36% |
| Guulin | 742 | 0.54% |
| Bayantooroi | 719 | -1.64% |
| Kherlenbayan-Ulaan | 503 | -0.98% |
