Tripura has a border with Assam of length (in km):

A state's total land periphery is made up of several distinct boundary segments — one for each neighbouring state or country it touches — because each segment runs along different terrain and was demarcated separately. Comparing a state's boundary figures therefore means checking which specific segment a given length belongs to, not just recalling one overall total.

Tripura is bordered by Assam along its north, by Mizoram along its east, and by Bangladesh, which wraps around its west, south, and part of its north. Tripura's official state geographical and economic-review records list each of these segments separately, and the segment shared with Assam — the shortest of the three — is recorded as 53 km.

This is corroborated by an independent official source, the state tourism department's geographical profile, which lists the same 53 km for the Assam segment, alongside 109 km for the Mizoram segment and 856 km for the much longer Bangladesh frontier. These three segments together account for Tripura's total periphery of a little over 1,000 km, confirming the Assam segment at 53 km.