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Population in Mongolia compared to Sierra Leone: Trends, Charts, Rankings

Updated on by Georank

The latest officially reported population of Mongolia was 3,568,978 in 2025 vs 8,819,794 people in Sierra Leone in 2025. In 2026, based on the adjusted UN estimation, the current Mongolia's population is 3,630,744 people compared to 9,090,531 in Sierra Leone.

Population statistics:

  • Sierra Leone's population is 2.5 times bigger than Mongolia's.
  • Mongolia is ranked the 132nd most populous country in the world, while Sierra Leone is the 100th.
  • The countries together account for 0.15% of the world: 0.04% for Mongolia vs 0.11% for Sierra Leone.
  • For the last 10 years, Mongolia has had an average growth rate of +1.71% per year vs +2.29% in Sierra Leone.
  • Since 2006, the population of Mongolia has increased from 2.57M people to 3.63M (41.4% growth), while Sierra Leone has grown from 5.62M to 9.09M (61.6% growth).

Mongolia vs Sierra Leone: population by year and forecast

Mongolia
Factual

Projection
Sierra Leone
Factual

Projection
1x
Year Population
Mongolia Sierra Leone
2100 5,630,532 16,107,087
2099 5,624,298 16,121,940
2098 5,616,442 16,135,035
2097 5,607,739 16,149,905
2096 5,598,366 16,160,672
2095 5,587,141 16,169,304
2094 5,575,743 16,168,902
2093 5,563,600 16,173,609
2092 5,550,506 16,170,778
2091 5,537,031 16,163,901
2090 5,522,419 16,154,165
2089 5,507,083 16,142,526
2088 5,491,226 16,128,775
2087 5,475,425 16,112,585
2086 5,459,661 16,085,549
2085 5,442,388 16,064,212
2084 5,424,928 16,040,563
2083 5,406,747 16,006,923
2082 5,388,623 15,970,872
2081 5,369,593 15,930,880
2080 5,349,817 15,892,665
2079 5,329,240 15,850,728
2078 5,307,283 15,801,450
2077 5,286,383 15,750,408
2076 5,264,220 15,695,310
2075 5,241,700 15,635,345
2074 5,218,897 15,580,279
2073 5,195,622 15,512,655
2072 5,172,532 15,442,481
2071 5,149,066 15,370,747
2070 5,124,853 15,293,426
2069 5,101,195 15,212,664
2068 5,077,035 15,124,069
2067 5,052,818 15,028,190
2066 5,027,552 14,931,295
2065 5,002,655 14,833,794
2064 4,978,185 14,736,872
2063 4,953,806 14,638,180
2062 4,929,364 14,525,736
2061 4,904,690 14,420,068
2060 4,878,877 14,307,451
2059 4,852,963 14,194,972
2058 4,826,761 14,077,124
2057 4,799,120 13,957,197
2056 4,771,151 13,832,494
2055 4,742,184 13,702,508
2054 4,711,735 13,576,231
2053 4,679,745 13,440,929
2052 4,646,658 13,299,910
2051 4,612,090 13,152,910
2050 4,576,701 13,006,688
2049 4,539,215 12,863,637
2048 4,500,638 12,712,671
2047 4,460,511 12,566,944
2046 4,419,188 12,411,042
2045 4,376,222 12,254,651
2044 4,333,010 12,088,895
2043 4,289,776 11,928,393
2042 4,245,757 11,767,372
2041 4,201,838 11,599,942
2040 4,158,320 11,428,331
2039 4,115,023 11,259,845
2038 4,072,646 11,097,180
2037 4,030,644 10,928,754
2036 3,989,867 10,757,928
2035 3,950,239 10,582,918
2034 3,911,316 10,411,088
2033 3,873,353 10,238,503
2032 3,836,311 10,059,929
2031 3,800,027 9,881,109
2030 3,763,374 9,705,485
2029 3,726,490 9,529,493
2028 3,688,767 9,358,412
2027 3,650,012 9,177,288
2026 3,610,395 8,998,902
2025 3,568,978 8,819,794
2024 3,524,788 8,642,022
2023 3,481,145 8,460,512
2022 3,433,748 8,276,807
2021 3,383,741 8,094,602
2020 3,327,204 7,912,558
2019 3,267,673 7,731,991
2018 3,208,189 7,554,563
2017 3,148,917 7,379,299
2016 3,088,856 7,205,328
2015 3,026,864 7,037,655
2014 2,963,113 6,876,385
2013 2,899,011 6,714,051
2012 2,839,705 6,551,080
2011 2,786,317 6,387,251
2010 2,738,622 6,222,714
2009 2,691,115 6,055,646
2008 2,643,201 5,894,722
2007 2,601,850 5,749,352
2006 2,567,168 5,624,466
2005 2,536,407 5,501,712
2004 2,508,412 5,355,717
2003 2,480,374 5,177,687
2002 2,449,027 4,971,435
2001 2,417,751 4,692,716
2000 2,388,299 4,423,611
1999 2,356,813 4,318,043
1998 2,323,809 4,295,785
1997 2,291,750 4,253,716
1996 2,259,507 4,199,210
1995 2,224,945 4,179,179
1994 2,189,395 4,173,105
1993 2,165,130 4,157,130
1992 2,167,790 4,166,366
1991 2,165,342 4,246,267
1990 2,098,710 4,196,828
1989 2,124,185 4,034,037
1988 2,076,322 3,934,517
1987 2,022,800 3,829,718
1986 1,970,965 3,728,380
1985 1,921,514 3,638,438
1984 1,874,349 3,558,758
1983 1,829,092 3,481,646
1982 1,785,364 3,408,183
1981 1,742,857 3,338,940
1980 1,701,335 3,272,089
1979 1,660,659 3,207,499
1978 1,619,468 3,145,517
1977 1,576,245 3,085,354
1976 1,531,945 3,028,820
1975 1,488,296 2,974,657
1974 1,446,050 2,920,459
1973 1,405,502 2,866,955
1972 1,366,821 2,814,388
1971 1,330,071 2,763,222
1970 1,295,272 2,712,286
1969 1,262,284 2,661,365
1968 1,229,930 2,611,532
1967 1,196,996 2,562,384
1966 1,163,754 2,514,638
1965 1,131,177 2,468,666
1964 1,100,234 2,424,390
1963 1,071,362 2,382,258
1962 1,041,444 2,342,242
1961 1,009,284 2,304,227
1960 977,595 2,268,356

Data sources: United Nations | World Population Prospects (2026–2100, retrieved 2026-07-08); World Bank | Health (1960–2025, retrieved 2026-07-08).

GeoRank.org/population/mongolia/sierra-leone | CC BY

From 2006 to 2016, the population of Mongolia increased by 521,688 people (a 20.3% growth), while Sierra Leone gained 1,580,862 people (a 28.1% growth).

For the next 10 years, from 2016 to 2026, Mongolia gained 541,888 people (a 17.5% growth), while Sierra Leone's population increased by 1,885,203 people (a 26.2% growth).

Mongolia was ranked 137th most populous country in 2006 and is 132nd in 2026. Sierra Leone was ranked 105th in 2006 and ranked 100th now.

The UN's World Population Prospects forecasts that in 24 years (in 2050) Mongolia's population will grow by 26.1% to 4,576,701 people with a rank change from 132nd to 130th. The population of Sierra Leone will increase by 43.1% to 13,006,688 people and rank change from 100th to 91st.

Mongolia is projected to reach its peak in 2100 at 5.63M people compared to the peak of 16.2M people in 2093 for Sierra Leone.

Population growth rate by year

Mongolia
Factual

Projection
Sierra Leone
Factual

Projection
1x
Year Growth rate
Mongolia Sierra Leone
2100 0.11% -0.09%
2099 0.14% -0.08%
2098 0.16% -0.09%
2097 0.17% -0.07%
2096 0.2% -0.05%
2095 0.2% 0.002%
2094 0.22% -0.03%
2093 0.24% 0.02%
2092 0.24% 0.04%
2091 0.26% 0.06%
2090 0.28% 0.07%
2089 0.29% 0.09%
2088 0.29% 0.1%
2087 0.29% 0.17%
2086 0.32% 0.13%
2085 0.32% 0.15%
2084 0.34% 0.21%
2083 0.34% 0.23%
2082 0.35% 0.25%
2081 0.37% 0.24%
2080 0.39% 0.26%
2079 0.41% 0.31%
2078 0.4% 0.32%
2077 0.42% 0.35%
2076 0.43% 0.38%
2075 0.44% 0.35%
2074 0.45% 0.44%
2073 0.45% 0.45%
2072 0.46% 0.47%
2071 0.47% 0.51%
2070 0.46% 0.53%
2069 0.48% 0.59%
2068 0.48% 0.64%
2067 0.5% 0.65%
2066 0.5% 0.66%
2065 0.49% 0.66%
2064 0.49% 0.67%
2063 0.5% 0.77%
2062 0.5% 0.73%
2061 0.53% 0.79%
2060 0.53% 0.79%
2059 0.54% 0.84%
2058 0.58% 0.86%
2057 0.59% 0.9%
2056 0.61% 0.95%
2055 0.65% 0.93%
2054 0.68% 1.01%
2053 0.71% 1.06%
2052 0.75% 1.12%
2051 0.77% 1.12%
2050 0.83% 1.11%
2049 0.86% 1.19%
2048 0.9% 1.16%
2047 0.94% 1.26%
2046 0.98% 1.28%
2045 1% 1.37%
2044 1.01% 1.35%
2043 1.04% 1.37%
2042 1.05% 1.44%
2041 1.05% 1.5%
2040 1.05% 1.5%
2039 1.04% 1.47%
2038 1.04% 1.54%
2037 1.02% 1.59%
2036 1% 1.65%
2035 1% 1.65%
2034 0.98% 1.69%
2033 0.97% 1.78%
2032 0.95% 1.81%
2031 0.97% 1.81%
2030 0.99% 1.85%
2029 1.02% 1.83%
2028 1.06% 1.97%
2027 1.1% 1.98%
2026 1.16% 2.03%
2025 1.25% 2.06%
2024 1.25% 2.15%
2023 1.38% 2.22%
2022 1.48% 2.25%
2021 1.7% 2.3%
2020 1.82% 2.34%
2019 1.85% 2.35%
2018 1.88% 2.38%
2017 1.94% 2.41%
2016 2.05% 2.38%
2015 2.15% 2.35%
2014 2.21% 2.42%
2013 2.09% 2.49%
2012 1.92% 2.56%
2011 1.74% 2.64%
2010 1.77% 2.76%
2009 1.81% 2.73%
2008 1.59% 2.53%
2007 1.35% 2.22%
2006 1.21% 2.23%
2005 1.12% 2.73%
2004 1.13% 3.44%
2003 1.28% 4.15%
2002 1.29% 5.94%
2001 1.23% 6.08%
2000 1.34% 2.44%
1999 1.42% 0.52%
1998 1.4% 0.99%
1997 1.43% 1.3%
1996 1.55% 0.48%
1995 1.62% 0.15%
1994 1.12% 0.38%
1993 -0.12% -0.22%
1992 0.11% -1.88%
1991 3.17% 1.18%
1990 -1.2% 4.04%
1989 2.31% 2.53%
1988 2.65% 2.74%
1987 2.63% 2.72%
1986 2.57% 2.47%
1985 2.52% 2.24%
1984 2.47% 2.21%
1983 2.45% 2.16%
1982 2.44% 2.07%
1981 2.44% 2.04%
1980 2.45% 2.01%
1979 2.54% 1.97%
1978 2.74% 1.95%
1977 2.89% 1.87%
1976 2.93% 1.82%
1975 2.92% 1.86%
1974 2.88% 1.87%
1973 2.83% 1.87%
1972 2.76% 1.85%
1971 2.69% 1.88%
1970 2.61% 1.91%
1969 2.63% 1.91%
1968 2.75% 1.92%
1967 2.86% 1.9%
1966 2.88% 1.86%
1965 2.81% 1.83%
1964 2.69% 1.77%
1963 2.87% 1.71%
1962 3.19% 1.65%
1961 3.24% 1.58%

Data sources: United Nations | World Population Prospects (2026–2100, retrieved 2026-07-08); World Bank | Health (1961–2025, retrieved 2026-07-08).

GeoRank.org/population/mongolia/sierra-leone | CC BY

In 2025, the population of Mongolia grew by 1.25%, while Sierra Leone's population grew by 2.06%.

Live population counters

Mongolia Sierra Leone
Current population
3630744
9090531
Population rank 132/197 100/197
Percent of world population 0.04% 0.11%
One net population change
11.9 minutes
2.96 minutes
One birth every
8.82 minutes
2.02 minutes
One death every
27.1 minutes
7.41 minutes
Daily growth/decline +121 +487
Annual growth/decline +44,190 +177,772
Annual growth/decline rate +1.25% +2.06%
Population growth rate rank 81/197 47/197
One migration net change every
4.63 days
46.6 minutes
Annual migration change +79 -11,309
Net migration rank 74/196 136/196
Foreign-born residents 22,589 49,997
Foreign-born residents rank 169/195 151/195
Foreign-born share of population 0.6% 0.6%
Foreign-born share rank 171/195 174/195

Natural population change vs migration

Mongolia
Natural

Migration
Sierra Leone
Natural

Migration
1x
Year Population change
Mongolia Sierra Leone
Natural Migration Natural Migration
2025 - 79 - -11,309
2024 40,182 83 189,234 -11,000
2023 46,995 0 188,788 -4,000
2022 47,730 0 186,625 -4,000
2021 52,109 0 183,326 -1,544
2020 60,888 0 181,015 1,292
2019 61,433 8,660 181,068 -2,238
2018 60,635 7,811 178,772 -2,741
2017 57,940 6,831 173,259 1,234
2016 62,086 5,633 168,784 4,657
2015 64,473 4,307 162,275 -356
2014 66,078 2,921 160,137 485
2013 62,618 1,505 161,265 2,773
2012 55,942 351 160,915 988
2011 50,711 -505 158,858 6,895
2010 44,914 -6,444 155,338 7,983
2009 48,876 -15,007 152,669 18,145
2008 45,843 -17,277 149,855 1,182
2007 39,636 -15,220 145,740 -6,042
2006 33,609 -11,934 144,127 -34,052
2005 29,290 -8,924 137,234 -1,805
2004 28,418 -8,148 132,661 23,897
2003 28,827 -7,986 130,312 69,185
2002 30,439 -8,934 126,429 86,578
2001 32,052 -10,244 116,647 227,791
2000 32,753 -11,241 110,754 83,013
1999 32,283 -13,481 102,295 -84,926
1998 31,757 -10,315 103,906 -76,766
1997 32,403 -9,132 105,433 -48,437
1996 33,741 -8,626 104,140 -52,110
1995 34,473 -7,346 100,885 -112,857
1994 34,711 -5,449 101,486 -77,371
1993 36,924 -5,429 103,317 -95,476
1992 42,437 -8,404 103,251 -129,565
1991 47,884 -11,427 105,477 -238,965
1990 49,443 -11,881 100,778 131,587
1989 51,420 -9,757 98,298 -5,079
1988 51,588 2,459 96,344 9,470
1987 51,140 1,855 94,235 9,558
1986 50,329 354 90,902 7,992
1985 49,944 -1,719 88,869 -7,873
1984 48,562 -2,452 87,072 -8,708
1983 46,919 -2,522 84,628 -8,783
1982 45,179 -2,132 82,457 -11,379
1981 43,588 -1,615 80,111 -12,699
1980 42,343 -1,268 77,932 -11,641
1979 41,568 -1,296 75,992 -13,095
1978 40,276 1,833 74,130 -13,073
1977 38,995 5,354 71,663 -12,399
1976 37,670 6,577 69,506 -15,686
1975 36,490 6,556 67,560 -13,058
1974 35,297 6,153 65,357 -11,473
1973 33,993 5,647 62,443 -9,322
1972 32,727 4,999 60,279 -8,267
1971 31,536 4,238 58,484 -8,162
1970 30,558 3,263 56,513 -4,957
1969 29,781 2,366 54,768 -4,485
1968 29,017 3,535 53,126 -3,743
1967 28,178 5,139 51,734 -2,819
1966 27,338 5,837 49,486 -2,911
1965 26,364 5,610 47,223 -1,851
1964 25,317 4,599 45,487 -2,308
1963 24,142 3,687 43,569 -2,480
1962 22,960 9,049 41,603 -2,658
1961 21,873 10,440 40,022 -2,947
1960 20,726 10,334 38,192 -3,528

Data sources: World Bank | Health (1960–2025, retrieved 2026-07-08).

GeoRank.org/population/mongolia/sierra-leone | CC BY

Over the last 10 years, 94.3% of the population change in Mongolia is from natural causes (a gain of 554,471 people) and 5.67% is from migration (a gain of 33,325 people). In Sierra Leone 99% is from natural causes (a gain of 1,793,146 people) and 1.03% is from migration (a loss of 18,696 people).

As of 2024, 22,589 residents or 0.6% of the population were not native-born in Mongolia, compared to 49,997 people or 0.6% in Sierra Leone.

Biggest cities by population

Mongolia
City Population
Ulaanbaatar 1.4M
Bulgan 12.3K
Sierra Leone
City Population
Freetown 951K
Bo 234K
Kenema 188K

Compare countries by 7 more topics

Population map with other countries

1x

Data sources: World Bank | Health (1960–2025, retrieved 2026-07-08); United Nations | World Population Prospects (1960–2026, retrieved 2026-07-08); U.S. Census Bureau (1960–2025, retrieved 2026-07-08); Central Intelligence Agency (CIA) (2000–2019, retrieved 2026-07-08).

GeoRank.org/population/mongolia/sierra-leone | CC BY

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Data sources:

  1. World Bank | Health (1960–2025, retrieved 2026-07-08)
  2. United Nations | World Population Prospects (1960–2100, retrieved 2026-07-08)
  3. U.S. Census Bureau (1960–2025, retrieved 2026-07-08)
  4. Central Intelligence Agency (CIA) (2000–2019, retrieved 2026-07-08)
  5. Wikidata (2026, retrieved 2026-07-08)

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