The two factors on which supply of labour depends include:
i. Population: The most important factor affecting the supply of labour in a country is its population. The larger the population, the larger will be the number of persons who will have the capacity to perform physical or mental work. Hence, the larger will be the supply of labour.
ii. Emigration (Out-migration) and Immigration (in-migration): Growth of population is determined not only by its natural growth but also by the out-migration and in-migration of people. If some people leave the country, the population goes down, and if some people enter the country from outside, the population goes up. In India, the in-migration of refugees after the partition in 1947 and the Bangladesh war of 1971 led to substantial increase in the supply of labour.