An urban agglomeration is defined as "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 (i.e. all the constituents put together) should not be less than 20,000.
Cities in bold are administered as Municipal corporations.
Ten largest urban agglomerations in Tamil Nadu
Urban agglomerations in Tamil Nadu
| Rank
|
City
|
District
|
Population
(2011)
|
| 1
|
Chennai
|
Chennai
|
8,696,010
|
| 2
|
Coimbatore
|
Coimbatore
|
2,151,466
|
| 3
|
Madurai
|
Madurai
|
1,462,420
|
| 4
|
Tiruchirappalli
|
Tiruchirappalli
|
1,021,717
|
| 5
|
Tiruppur
|
Tiruppur
|
962,982
|
| 6
|
Salem
|
Salem
|
919,950
|
| 7
|
Erode
|
Erode
|
521,776
|
| 8
|
Tirunelveli
|
Tirunelveli
|
498,924
|
| 9
|
Vellore
|
Vellore
|
481,966
|
| 10
|
Thoothukudi
|
Thoothukudi
|
410,760
|
| 11
|
Dindigul
|
Dindigul
|
292,132
|
| 12
|
Thanjavur
|
Thanjavur
|
290,724
|
| 13
|
Ranipet
|
Ranipet
|
262,346
|
| 14
|
Sivakasi
|
Virudhunagar
|
234,688
|
| 15
|
Karur
|
Karur
|
233,763
|
| 16
|
Udhagamandalam
|
Nilgiris
|
233,374
|
| 17
|
Hosur
|
Krishnagiri
|
229,507
|
| 18
|
Nagercoil
|
Kanyakumari
|
224,849
|
| 19
|
Kancheepuram
|
Kancheepuram
|
221,749
|
| 20
|
Komarapalayam
|
Namakkal
|
194,992
|
| 21
|
Karaikudi
|
Sivaganga
|
181,347
|
| 22
|
Neyveli
|
Cuddalore
|
178,925
|
| 23
|
Cuddalore
|
Cuddalore
|
173,361
|
| 24
|
Kumbakonam
|
Thanjavur
|
167,098
|
| 25
|
Tiruvannamalai
|
Tiruvannamalai
|
144,683
|
| 26
|
Pollachi
|
Coimbatore
|
135,235
|
| 27
|
Rajapalayam
|
Virudhunagar
|
130,119
|
| 28
|
Gudiyatham
|
Vellore
|
124,274
|
| 29
|
Pudukottai
|
Pudukottai
|
117,215
|
| 30
|
Vaniyambadi
|
Tirupattur
|
116,712
|
| 31
|
Ambur
|
Tirupattur
|
113,856
|
| 32
|
Nagapattinam
|
Nagapattinam
|
102,838
|