Each new seat can be described as a combination of parts of old seats. These table show this decomposition. The winner of the old seat at the 2010 election is shown by party colour, as is the implied winner of the new seat.
The implied results are now calculated using the local election results for the wards which make up each old seat. This should be more accurate than the earlier implied results which assumed each constituency was homogeneous.
| New seat | Primary component | Secondary component(s) |
|---|---|---|
| Alyn and Deeside | 100% of Alyn and Deeside | 34.8% of Delyn |
| Conwy and Colwyn | 72.7% of Clwyd West | 70.4% of Aberconwy |
| Denbigh and Montgomeryshire North | 56.7% of Clwyd South | 45.8% of Montgomeryshire
27.3% of Clwyd West
19.7% of Vale of Clwyd
|
| Flint and Denbighshire North | 80.3% of Vale of Clwyd | 65.2% of Delyn |
| Wrexham Maelor | 100% of Wrexham | 43.3% of Clwyd South |
| New seat | Primary component | Secondary component(s) |
|---|---|---|
| Caerfyrddin | 92.0% of Carmarthen East and Dinefwr | 41.0% of Carmarthen West and Pembrokeshire South |
| Ceredigion and Pembrokeshire North | 100% of Ceredigion | 24.2% of Preseli Pembrokeshire
8.0% of Carmarthen East and Dinefwr
|
| Llanelli | 100% of Llanelli | 31.7% of Gower |
| Pembrokeshire South | 75.8% of Preseli Pembrokeshire | 59.0% of Carmarthen West and Pembrokeshire South |
| New seat | Primary component | Secondary component(s) |
|---|---|---|
| Blaenau Gwent | 100% of Blaenau Gwent | 43.6% of Islwyn |
| Caerphilly | 90.5% of Caerphilly | 36.0% of Islwyn |
| Monmouthshire | 87.5% of Monmouth | 30.8% of Newport East |
| Newport | 69.2% of Newport East | 57.0% of Newport West |
| Torfaen | 100% of Torfaen | 12.5% of Monmouth
11.0% of Newport West
|
| New seat | Primary component | Secondary component(s) |
|---|---|---|
| Gwynedd | 100% of Dwyfor Meirionnydd | 54.4% of Arfon
15.7% of Aberconwy
|
| Ynys Mon and Bangor | 100% of Ynys Mon | 45.6% of Arfon
14.0% of Aberconwy
|
| New seat | Primary component | Secondary component(s) |
|---|---|---|
| Bridgend | 100% of Bridgend | 26.6% of Ogmore |
| Merthyr Tydfil, Rhumney and Lower Cynon | 100% of Merthyr Tydfil and Rhymney | 27.9% of Cynon Valley
9.5% of Caerphilly
4.6% of Islwyn
|
| Pontypridd | 90.1% of Pontypridd | 19.3% of Ogmore
14.9% of Cynon Valley
8.0% of Rhondda
|
| Rhondda and Aberdare | 92.0% of Rhondda | 57.2% of Cynon Valley |
| New seat | Primary component | Secondary component(s) |
|---|---|---|
| Brecon, Radnor and Montgomery | 100% of Brecon and Radnorshire | 54.2% of Montgomeryshire |
| New seat | Primary component | Secondary component(s) |
|---|---|---|
| Cardiff Central | 90.8% of Cardiff Central | 24.7% of Cardiff North |
| Cardiff North and Gwent South West | 67.1% of Cardiff North | 32.0% of Newport West
15.8% of Islwyn
|
| Cardiff South and Penarth | 95.2% of Cardiff South and Penarth | 9.2% of Cardiff Central |
| Cardiff West | 100% of Cardiff West | 9.9% of Pontypridd
8.2% of Cardiff North
|
| Vale of Glamorgan | 100% of Vale of Glamorgan | 4.8% of Cardiff South and Penarth |
| New seat | Primary component | Secondary component(s) |
|---|---|---|
| Aberavon and Ogmore | 86.5% of Aberavon | 54.0% of Ogmore |
| Gower and Swansea West | 73.2% of Swansea West | 46.7% of Gower |
| Neath and the Swansea Valley | 100% of Neath | 11.8% of Gower
13.5% of Aberavon
8.1% of Swansea East
|
| Swansea East | 91.9% of Swansea East | 26.8% of Swansea West
9.8% of Gower
|