India’s revised coastline length

• The length of India’s coastline of 7,516.6 km has been re-assessed to 11,098.81 km by National Hydrographic Office (NHO) in coordination with Survey of India (SoI) as per the latest terms of references provided by National Security Council Secretariat (NSCS). 

• The updated measurements were carried out using modern Geographic Information System (GIS) software and high-resolution data of High-Water Line (HWL) based on latest surveys thereby capturing more intricate details, the Ministry of Earth Sciences said in a reply in Rajya Sabha.

• Coastal Protection and Development Advisory Committee (CPDAC) accepted the revised coastline length of India after obtaining concurrence from all coastal states/UTs. 

• Based on the report published by Survey of India, the revised length of coastline was promulgated by the Ministry of Ports Shipping and Waterways (MoPSW) circular on April 29, 2025. 

• Accordingly, the state/UT wise length of the coastline of India has changed. 

Probable reasons for change in coastline length

• The main reason for the deviation in the coastline length of 7,516.6 kms as per records of Ministry of Home Affairs (MHA) and the re-verified coastline length of 11,098.81 kms is due to the probable variation in scale and calculation methods. 

• The length of coastline calculated in the 1970s might have been computed from the then available records at the scale of 1:4,500,000 or smaller whereas the re-verified data has been computed at the scale of 1:250,000. 

• It is understood that the length of coastline is liable to vary when it is measured from maps of different scales. 

• The larger the scale of the map, greater may be the outcome of the length. 

• This is because larger scale data capture more intricate details like bays, inlets, and minor irregularities that are smoothed out at smaller scale data. 

• Further, conventional/ manual methods might have been used for the computation of the 1970 data whereas modern GIS software have been used for the computation of the re-verified data.

• The number of offshore islands/islets of India are finalised as 1,298 offshore islands/islets (1,059 islands and 239 islets) in the reconciliation exercise of the offshore islands of India. 

• Secondly,the length of offshore islands has been added in the total length of there-verified coastline which might have been left out in the 1970s coastline length due to scale constraint and conventional/ manual measuring methods. 

• The updated coastline supports better planning for developmental activities such as ports, infrastructure, tourism zones, and disaster-risk assessments, enabling governments to prepare more effectively for cyclones, erosion, flooding etc. 

• Improved baseline data supports India’s maritime in improved management of territorial waters and Exclusive Economic Zone (EEZ) boundaries, and enhances the security.