Since independence, four population censuses have been conducted: in 1951, 1961, 1972 and 1981. The new census was due in 1991, but as a result of political reservation of the provinces and other political forces it could not be executed. The data provided by previous censuses does not present a consistent trend. The Planning Commission had indicated under-enumeration of population in the 1961 census by 7.5 percent. Usually male enumerators are deputed to interview the respondents, male members of the household in most cases. This way of proceeding may cause underreporting of women and girls, especially in figures on the productive sector. Female family members are usually less reported due to the social desirability factor. Their participation in the productive sector is also ignored. All the enumerators of census as well as the supervisory officials were government employees who, as a matter of routine, were not very careful about the validity of censuses. Supervision has also been ineffective and making up census data has been a much applied practice. Keeping in view all these facts, reliability of all these censuses can be questioned.

The geographical boundaries of Kohlu district have been changing from time to time, therefore, it seems quite difficult to explain changes in the population size, annual growth rate and the population density.

The population growth rate for Kohlu district has been inconsistent right from the initial censuses. During the inter-census period 1951-61 the population of Kohlu district portrayed a negative growth trend with an annual decrease of 1.7 percent. In the next 11 years (1961-72) this situation became absolutely inverse with a significantly high growth rate (7.3% per annum). Then in the next inter-censal period (1972-81) this rate decreased to less than a half of the previous one (i.e., 3.1%). The NIPS has projected the population of Kohlu for 1995 as 105,050. This projected population of Kohlu shows an annual growth rate of 2.8 percent during 1981-95. These highly fluctuating growth rates indicate unreliability of the census data, hence, cannot be explained; specially in the absence of birth and death rates at the district level.

According to the 1981 census, the female population in age group 0-4 was approximately double the male population and females outnumbered the males very significantly up to the age 10. Afterwards the female population decreases significantly as compared to the male population. This situation persists up to the age of 35. It supports the assumption that poor health care strikes females more harshly than males. The males in their later ages again show potential for their survival as they outnumber the females after 60 years of age. However, a significantly high proportion of female babies in the population of Kohlu district remains unexplained. Despite the suspected under-enumeration of females, this high proportion of female babies has resulted in approximately equal number of males and females in Kohlu district. The final conclusion can only be drawn after availability of age and sex specific birth and death rates at the district level.

In 1981, infants constituted 2.2 percent of the total population while the children under 5 were 13.0 percent. More than half (52.3%) of the total population was adult (18 years of age and above), while the population eligible to vote (21 years of age and above) was 44.5 percent. Women of child bearing age (15-49 years) were 20.7 percent. The married population constituted 78.5 percent of the population of 15 years and above (which itself is 57.8% of the total population) while 19.2 percent of this population were never married. The percentage of widowers was 2.2 percent and divorcees were less than 0.1 percent. This low ratio of divorcee indicates highly negative attitude of the people towards divorce. The average age at marriage for females in Kohlu district was 17.1 years which was lowest in the country. A relatively low total fertility rate (6.3) does not correspond to this lowest age at marriage. This also indicate lack of internal consistency of census data. The child-woman ratio was 266 children (under age five) per thousand women of child bearing age (15-49 years).

According to 1981 census the average household size in Kohlu district was 6.8. The average number of children (under the age of 15 years) per household was less than three (2.9).

In 1981, less than a half (45.6%) of the population in Kohlu district was dependent, either below the age of 15 or 65 years of age and above. The child dependency (ratio of people under age 15 to those ages 15-64) was 77.7 percent while the old-age dependency (ratio of people age 65 or older to those ages 15-64) was 6.3 percent. This situation increases the economic pressure for the families which may result in child labour and malnutrition of both women and children, the most neglected strata of the society.

According to the 1981 census, the entire Kohlu district is defined as rural. No town of the district has ever been designated as urban area.

The main human settlements of the district are Kohlu town, Kahan, Mawand, Sohr Rohd, Basti Mir Hazar, Karam Khan Shehr, Kote Shehr, Baladhaka, Malikzai, Uryani, Pazha, Kunal and Sufaid. Administrative offices are located in Kohlu town which is district headquarters as well. According to the 1981 census, there were 196 mauzas/villages in the district. There was no mauza having individual population above 5,000 and only 3 mauzas had a population between 2,000 and 4,999.

The Balochs constitute an overwhelming majority (above 90%) of the population in Kohlu district out of which a significant majority belongs to Marri tribe. The Marris are divided into three main clans – Gazani, Loharani and Bijarani – which are further subdivided into many sub-clans. Another remarkable ethnic group residing in the district is Zarkoon who speaks Pushto. According to the 1981 census, Balochi is the native language of 93.8 percent of the households followed by Pushto which is spoken in 2.9 percent of the homes. Other languages, including Saraiki, Punjabi, Urdu, Sindhi and Brahui, are spoken in 3.3 percent of the households.

The Marris, who constitute a significant majority of the population in Kohlu district, basically live a nomadic life. Their prime economic activity is livestock raising. They wander about throughout the year. Wherever water is available for irrigation permanent settlements are found around the agricultural lands. The inhabitants of these settlements are either land owners or tenants. Some of the people migrate to other districts for service and labour.

According to 1981 census the total in-migrants were 1,586 with 75.5 percent males and 24.5 percent females. During the last ten years (1971-81) 25,641 persons had gone abroad and were still residing there at the time of census enumeration. This large scale out-migration (emigration) was a result of insurgence – farrari movement – against the oppressive strategy of the government. Majority of the people from Marri tribe migrated to Afghanistan. However these figures are for the area which was included in Kohlu district in 1981; including Sui sub-division. There is no recent data available on the extent of migration in Kohlu district.