Nathnagar

The geographic coordinates of Nathnagar Assembly constituency are: 25°12'11.9"N 86°57'31.3"E. This constituency falls in Bhagalpur district of Bihar and in the Bhagalpur region. Nathnagar shares its borders with seven other Assembly constituencies. Other Bihar Assembly constituencies adjacent to Nathnagar are: Bihpur, Gopalpur, Bhagalpur, Kahalgaon, Dhauraiya, Amarpur, Sultanganj. This constituency shares an inter-state border with .

There were a total of 335528 registered voters on the electoral rolls for the 2025 Assembly election in Nathnagar Assembly constituency, of which 171487 were male, 164033 female and 8 of the third gender. In the 2020 Assembly elections, there were a total of 326124 registered voters, of which 172849 were male, 153260 female and 15 from the third gender. In the 2015 Assembly elections, there were a total of 300682 registered voters, of which 160229 were male, 140442 female and 614 from the third gender. In 2010 elections, there were a total of 243019 registered voters in this constituency, of which 132347 were male and 110672 female and 385 from the third gender.

The number of service voters in this Assembly constituency was 785 in 2020, 11 in 2015, and 0 in 2010.

The electorate gender ratio (number of female voters per 1000 male voters) in this constituency in 2025 was 957, in 2020 it was 887, 877 in 2015, and 836 in 2010.

Nathnagar Assembly constituency will go to the polls in Phase 2 of the 2025 Bihar Assembly elections on Tuesday, November 11, 2025. The counting of votes is on Friday, November 14, 2025.

In the 2020 state Assembly elections, this seat voted in Phase 2 on Tuesday, November 3, 2020 and the results were declared on Tuesday, November 10, 2020.

In the 2015 state Assembly elections, this seat voted in Phase 1 on Monday, October 12, 2015 and the results were declared on Sunday, November 8, 2015.

In the 2010 polls, this constituency voted in Phase 4 on Monday, November 1, 2010 and the results were declared on Wednesday, November 24, 2010.

Assembly constituency no.158. Nathnagar comprises of the following areas of Bhagalpur district in the Bhagalpur region of Bihar: CD Blocks Nathnagar & Sabour; Gram Panchayats Puraini North, Puraini South, Baluachak Puraini, Sanholi, Baijani, Khiribandh, Jamani, Saino, Bhawanipur Desri, Chandapur, Jagdishpur, SonuchakPuraini, Imampur, Shajangi & Habibipur (CT) of Jagdishpur CD Block

This constituency covers an approximate area of 316.28 square kilometers and the geographic coordinates of Nathnagar is: 25°12'11.9"N 86°57'31.3"E.

A total of seven Assembly constituencies in the state of Bihar share borders with Nathnagar constituency, which are: Bihpur, Gopalpur, Bhagalpur, Kahalgaon, Dhauraiya, Amarpur, Sultanganj. This constituency shares an inter-state border with .

According to data released by the Election Commission of India, in the 2025 Bihar Assembly elections, the estimated voter turnout in this Nathnagar constituency was 71.55%. In 2020, this seat registered a turnout of 59.82%, while it was 56.47% in 2015, and 50.31% in 2010.

In the 2020 Bihar Assembly elections, Ali Ashraf Siddiqui of RJD won in this constituency beating Lakshmi Kant Mandal of JDU by a margin of 7756 votes which was 3.98% of the total votes cast. In 2015, Ajay Kumar Mandal of JDU was the winner in this seat beating Amar Nath Prasad Alies Amar Singh Kushwaha of LJP by a margin of 7825 votes which was 4.61% of the total votes polled in the constituency. In the 2010 Assembly elections, Ajai Kumar Mandal of JDU won this seat defeating Abu Kaishar of RJD by a margin of 4727 votes which was 3.87% of the total votes polled for the seat.

In the 2020 Bihar Assembly elections, Ali Ashraf Siddiqui of RJD had a vote share of 40.41% in this seat. In the 2015 Assembly elections, Ajay Kumar Mandal of JDU got a vote share of 39.16% , In the 2010 Assembly elections, Ajai Kumar Mandal of JDU got a vote share of 34.43% in Nathnagar.