As per  population figures of 2011 Census, detail is as follows-

Population 3921971
Population density 1101 per sq. km
Population growth 19%
Sex ratio 910 per 1000 male
Literacy rate 44%
Languages spoken Maithili, Hindi and Urdu
Area 2279 Sq. Km No. of Revenue Division 1
No. of Taluks 18 No. of Revenue Mandals 3
No. of Gram Panchayat 324 No. of Municipal Council 1
No. of Municipal Corporation 1 No. of Census Block 18
No. of of Revenue Villages 1269 No. of Circles 18