| Official Name: | Dasar |
| Settlement Type: | Upazila |
| Coordinates: | 23.09°N 90.13°W |
| Subdivision Type: | Country |
| Subdivision Name: |  Bangladesh |
| Subdivision Type1: | Division |
| Subdivision Type2: | District |
| Subdivision Name1: | Dhaka |
| Subdivision Name2: | Madaripur |
| Area Total Km2: | 76.08 |
| Population Total: | 75172 |
| Population As Of: | 2022 |
| Population Footnotes: | [1] |
| Population Density Km2: | auto |
| Postal Code Type: | Postal code |
| Postal Code: | 7920[2] |
| Timezone: | BST |
| Utc Offset: | +6 |
Dasar Upazila is an upazila of Madaripur district in the Division of Dhaka, Bangladesh.[3]
A police investigation centre was set up in Dasar on February 2, 2012. Later, the Dasar Thana (police station) was formed on March 2, 2013, with five unions of Kalkini Upazila.[4] Shortly thereafter, the local administration proposed to convert Dasar into upazila. At the meeting of the National Implementation Committee on Administrative Restructuring (NICAR) on November 20, 2017, the Dasar Thana (police station) was supposed to be upgraded to upazila but it was rejected and asked to conduct a further examination.[5] Then on 26 July 2021, it was decided to make Dasar a full-fledged upazila at the 117th meeting of NICAR.[6]
Dasar Upazila consists of 5 unions and 67 mouzas.[7]
The geographical location of Dasar Upazila is . Its total area is 76.08 km2.[8] Dasar upazila is bounded on the north by Madaripur Sadar upazila, on the south by Agailjhara Upazila, on the east by Kalkini upazila and on the west by Kotalipara upazila. The Palrodi river flows over the upazila.
According to the 2011 Census of Bangladesh, Dasar Upazila had 15,595 households and a population of 71,494. 16,849 (23.57%) were under 10 years of age. Dasar had a literacy rate (age 7 and over) of 54.02%, compared to the national average of 51.8%, and a sex ratio of 986 females per 1000 males. The entire population lived in rural areas.[9] [10]