One sub-centre covers:
The sub-centre is the peripheral outpost of the existing health delivery system in rural areas. 
One sub-centre covers a population of 5000 in general and 3000 in hilly, tribal and backward areas. 
The functions of a sub-centre are limited to mother and child health care, family planning and immunization. 
There are two functionaries at the level of the subcentre: one male and one female multipurpose health worker. 
One health assistant (HA) will supervise the work of 6 health workers. 
Six subcentres are located in each PHC area.

Essentials of preventive and community dentistry
Soben Peter
5th edition
Page number 226
1000 population
2000 population
4000 population
5000 population