Notional results for a UK general election on 12 December 2019 Wales - by majority
A notional general election to the 58th Parliament of the United Kingdom with an electorate of 47,558,398, having 32,014,119 valid votes.
| Constituency | Winning party | Valid votes | Majority (votes) | Majority (%) |
| Rhondda and Ogmore | Lab | 42,549 | 17,377 | 40.8% |
| Cardiff East | Lab | 46,781 | 17,079 | 36.5% |
| Merthyr Tydfil and Aberdare | Lab | 43,106 | 13,410 | 31.1% |
| Blaenau Gwent and Rhymney | Lab | 42,094 | 12,969 | 30.8% |
| Aberafan Maesteg | Lab | 44,423 | 13,457 | 30.3% |
| Montgomeryshire and Glyndŵr | Con | 51,208 | 14,765 | 28.8% |
| Cardiff South and Penarth | Lab | 50,370 | 11,851 | 23.5% |
| Swansea West | Lab | 44,199 | 10,037 | 22.7% |
| Monmouthshire | Con | 52,872 | 10,837 | 20.5% |
| Cardiff West | Lab | 51,941 | 10,546 | 20.3% |
| Dwyfor Meirionnydd | PC | 50,518 | 9,880 | 19.6% |
| Pontypridd | Lab | 45,579 | 8,798 | 19.3% |
| Neath and Swansea East | Lab | 44,824 | 8,451 | 18.9% |
| Brecon, Radnor and Cwm Tawe | Con | 52,276 | 9,091 | 17.4% |
| Mid and South Pembrokeshire | Con | 54,971 | 8,621 | 15.7% |
| Caerphilly | Lab | 45,069 | 6,901 | 15.3% |
| Cardiff North | Lab | 54,709 | 7,579 | 13.9% |
| Newport East | Lab | 46,405 | 5,239 | 11.3% |
| Clwyd East | Con | 52,820 | 5,284 | 10.0% |
| Torfaen | Lab | 43,553 | 4,110 | 9.4% |
| Llanelli | Lab | 43,892 | 3,793 | 8.6% |
| Caerfyrddin | Con | 53,342 | 4,529 | 8.5% |
| Wrexham | Con | 47,123 | 3,939 | 8.4% |
| Gower | Lab | 54,231 | 3,181 | 5.9% |
| Clwyd North | Con | 51,289 | 2,834 | 5.5% |
| Bridgend | Con | 46,708 | 2,553 | 5.5% |
| Ynys Môn | Con | 36,552 | 1,968 | 5.4% |
| Vale of Glamorgan | Con | 49,993 | 2,566 | 5.1% |
| Newport West and Islwyn | Lab | 48,537 | 2,001 | 4.1% |
| Ceredigion Preseli | PC | 51,667 | 1,443 | 2.8% |
| Bangor Aberconwy | Con | 48,407 | 749 | 1.5% |
| Alyn and Deeside | Lab | 52,350 | 411 | 0.8% |
Estimates of the 2019 general election result in new constituencies
BBC News, ITV News, Sky News and the Press Association have together produced estimates of the 2019 general election result as if the new constituencies recommended by the separate Parliamentary Boundary Commissions for England, Scotland, Wales and Northern Ireland had then been in existence.
Rallings & Thrasher, Professor David Denver (Scotland), Nicholas Whyte (NI) for Sky News, PA, BBC News and ITV News.
An explanation of the methods used and the electoral impact of the changes can be found in the linked document.