Orkney Islands tops the ranking, with 21,961 residents, ahead of Shetland Islands and Na h-Eileanan an Iar. The full ranking is below, each entry linked to its page.

# County Population
1 Orkney Islands 21,961
2 Shetland Islands 22,978
3 Na h-Eileanan an Iar 26,135
4 Rutland 44,041
5 Clackmannanshire 51,026
6 Merthyr Tydfil 58,753
7 Blaenau Gwent 65,205
8 Isle of Anglesey 68,852
9 Ceredigion 71,411
10 Inverclyde 77,652
11 Argyll and Bute 85,698
12 West Dunbartonshire 88,383
13 Monmouthshire 91,434
14 Torfaen 92,056
15 Stirling 92,390
16 Moray 93,691
17 Midlothian 96,532
18 Denbighshire 96,586
19 East Renfrewshire 96,750
20 East Dunbartonshire 107,164
21 Angus 111,522
22 South Ayrshire 113,064
23 East Lothian 113,073
24 Conwy 113,823
25 Scottish Borders 116,207
26 East Ayrshire 118,455
27 Gwynedd 118,529
28 Pembrokeshire 123,443
29 Powys 129,961
30 The Vale of Glamorgan 131,305
31 Wrexham 133,476
32 North Ayrshire 133,991
33 Isle of Wight 140,460
34 Neath Port Talbot 143,741
35 Dumfries and Galloway 145,892
36 Bridgend 147,575
37 Dundee City 151,073
38 Perth and Kinross 151,271
39 Flintshire 157,266
40 Falkirk 158,255
41 Newport 160,728
42 Caerphilly 178,349
43 West Lothian 180,252
44 Renfrewshire 185,061
45 Carmarthenshire 185,368
46 Herefordshire 187,551
47 Highland 229,318
48 Aberdeen City 231,144
49 Rhondda Cynon Taf 233,945
50 Swansea 240,159
51 Aberdeenshire 256,371
52 Northumberland 318,641
53 South Lanarkshire 328,758
54 North Lanarkshire 344,263
55 Cardiff 363,589
56 Fife 372,984
57 Bristol 475,648
58 Cumbria 501,093
59 Shropshire 502,842
60 City of Edinburgh 514,073
61 Cornwall 570,757
62 Warwickshire 595,446
63 East Riding of Yorkshire 599,058
64 Worcestershire 607,667
65 Glasgow City 617,149
66 Bedfordshire 706,591
67 Oxfordshire 724,367
68 Wiltshire 739,392
69 Suffolk 755,855
70 Dorset 775,383
71 Northamptonshire 785,298
72 East Sussex 824,106
73 Buckinghamshire 846,864
74 West Sussex 884,209
75 Cambridgeshire 899,729
76 County Durham 914,238
77 Norfolk 914,439
78 Gloucestershire 936,637
79 Berkshire 945,736
80 Somerset 983,434
81 Derbyshire 1,057,684
82 Leicestershire 1,081,898
83 Lincolnshire 1,082,550
84 Cheshire 1,093,983
85 Tyne and Wear 1,131,809
86 Staffordshire 1,138,148
87 North Yorkshire 1,140,932
88 Nottinghamshire 1,145,226
89 Hertfordshire 1,182,100
90 Surrey 1,194,814
91 Devon 1,216,729
92 South Yorkshire 1,376,161
93 Merseyside 1,418,883
94 Lancashire 1,535,323
95 Kent 1,852,764
96 Hampshire 1,863,451
97 Essex 1,879,394
98 West Yorkshire 2,327,972
99 Greater Manchester 2,864,829
100 West Midlands 2,913,889
101 Greater London 8,805,417

Source: ONS Census 2021. Compiled by Postcodes UK.

Frequently asked questions

Which is the least populous county in the UK?

Orkney Islands tops the list, with 21,961 residents, followed by Shetland Islands and Na h-Eileanan an Iar.

How is this ranking measured?

This ranking is based on ONS Census 2021. It covers the ceremonial counties of England and the council and principal areas of Scotland and Wales.