List of cities in Bihar by population
Bihar is administratively divided into 9 divisions and 38 districts. For the administration of urban areas, Bihar has 19 municipal corporations, 89 nagar parishads, and 154 nagar panchayats.
| Rank | Name | Image | District | Type* | Population 2011 |
| 1 | Patna | Patna | UA | 2,061,834 | |
| 2 | Gaya | Gaya | UA | 474,093 | |
| 3 | Bhagalpur | Bhagalpur | UA | 412,209 | |
| 4 | Muzaffarpur | Muzaffarpur | UA | 354,462 | |
| 5 | Bihar Sharif | Nalanda | City | 337,819 | |
| 6 | Purnia | Purnia | UA | 325,307 | |
| 7 | Darbhanga | Darbhanga | UA | 296,039 | |
| 8 | Sasaram | Rohtas | City | 264,709 | |
| 9 | Arrah | Bhojpur | City | 261,430 | |
| 10 | Samastipur | Samastipur | City | 253,136 | |
| 11 | Begusarai | Begusarai | City | 252,008 | |
| 12 | Katihar | Katihar | UA | 240,838 | |
| 13 | Bettiah | West Champaran | UA | 237,254 | |
| 14 | Motihari | East Champaran | City | 221,646 | |
| 15 | Saharsa | Saharsa | City | 216,491 | |
| 16 | Munger | Munger | City | 213,303 | |
| 17 | Chhapra | Saran | UA | 202,352 | |
| 18 | Siwan | Siwan | Town | 191,385 | |
| 19 | Hajipur | Vaishali | Town | 191,275 | |
| 20 | Madhubani | Madhubani | Town | 164,165 |
- UA=Urban Agglomeration
Urban agglomeration
In the census of India 2011, an urban agglomeration is defined as follows:"An urban agglomeration is a continuous urban spread constituting a town and its adjoining outgrowths, or two or more physically contiguous towns together with or without outgrowths of such towns. An Urban Agglomeration must consist of at least a statutory town and its total population should not be less than 20,000 as per the 2001 Census. In varying local conditions, there were similar other combinations which have been treated as urban agglomerations satisfying the basic condition of contiguity."
Constituents of urban agglomerations in Bihar
The constituents of urban agglomerations in Bihar, with a population of 100,000 or above, are noted below:- Patna Urban Agglomeration includes Patna, Badalpura, Pataliputra Housing Colony, Phulwari Sharif, Nohsa, Danapur, Dinapur Cantonment, Khagaul and Saidpura.
- Gaya Urban Agglomeration includes Gaya, Kaler and Paharpur.
- Bhagalpur Urban Agglomeration includes Bhagalpur,Habibpur,sabour and Nathnagar
- Muzaffarpur Urban Agglomeration includes Muzaffarpur, Damodarpur, Dumari urf Damodarpur Shahjahan, Majhauli Khetal, Yehiapur and Shekhpura.
- Purnia Urban Agglomeration includes Purnia and Kasba.
- Darbhanga Urban Agglomeration includes Darbhanga, Padri and Bahadurpur.
- Katihar Urban Agglomeration includes Katihar and Katihar Railway Colony.
- Chapra Urban Agglomeration includes Chapra and Sanrha.
- Bettiah Urban Agglomeration includes Bettiah, Tola Mansaraut, Kargahia Purab and Hat Saraiya.
- Nawada Urban Agglomeration includes Nawada and Bhadauni.
- Buxar Urban Agglomeration includes Buxar and Sarimpur.
- Sitamarhi Urban Agglomeration includes Sitamarhi, Rajopatti urf Kota Bazar, Talkhapur Dumra and Dumra.
Urban agglomeration constituents
Urban agglomerations constituents with a population above 100,000 as per 2011 census are shown in the table below.| Urban agglomeration | Name of constituent | District | Type | Population 2011 | Male | Female | Population | Literacy rate |
| Patna | Patna Municipal Corporation | Patna district | M Corp. | 1,683,200 | 894,158 | 789,042 | 190,496 | 84.71 |
| Munger | Munger | Munger district | M Corp. | 3,88,000 | 2,00,000 | 1,88,000 | 42,260 | 81.83 |
| Gaya | Gaya | Gaya district | M Corp. | 463,454 | 245,764 | 217,690 | 59,015 | 85.74 |
| Bhagalpur | Bhagalpur | Bhagalpur district | M Corp. | 398,138 | 212,005 | 186,113 | 53,775 | 81.16 |
| Muzaffarpur | Muzaffarpur | Muzaffarpur district | M Corp. | 351,838 | 186,145 | 165,693 | 42,276 | 85.16 |
| Darbhanga | Darbhanga | Darbhanga district | M Corp. | 294,116 | 154,970 | 139,146 | 40,392 | 80.88 |
| Purnia | Purnia | Purnia district | M Corp. | 280,547 | 148,021 | 132,526 | 41,046 | 74.48 |
| Katihar | Katihar | Katihar district | M Corp. | 225,982 | 119,142 | 106,840 | 31,036 | 79.87 |
| Sasaram | Rohtas | Rohtas district | M Corp. | 222,597 | 106,250 | 95,347 | 27,668 | 89.30 |
| Bettiah | Bettiah | West Champaran district | M Corp. | 132,896 | 70,381 | 62,515 | 18,203 | 82.54 |
| Buxar | Buxar | district | NP | 102,591 | 54,123 | 84,468 | 13,639 | 94.16 |