Notional results for a UK general election on 12 December 2019 Elections contested by Plaid Cymru
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 | Electorate | Turnout | Votes | Vote share | Position |
| Dwyfor Meirionnydd | 72,533 | 69.6% | 23,110 | 45.7% | 1st |
| Ceredigion Preseli | 74,063 | 69.8% | 16,045 | 31.1% | 1st |
| Caerfyrddin | 72,683 | 73.4% | 16,362 | 30.7% | 2nd |
| Ynys Môn | 52,415 | 69.7% | 10,418 | 28.5% | 3rd |
| Wrexham | 70,964 | 66.4% | 2,960 | 6.3% | 3rd |
| Rhondda and Ogmore | 73,557 | 57.8% | 5,290 | 12.4% | 3rd |
| Pontypridd | 73,743 | 61.8% | 4,963 | 10.9% | 3rd |
| Mid and South Pembrokeshire | 76,820 | 71.6% | 2,917 | 5.3% | 3rd |
| Llanelli | 69,895 | 62.8% | 9,280 | 21.1% | 3rd |
| Clwyd North | 76,150 | 67.4% | 3,713 | 7.2% | 3rd |
| Cardiff West | 73,947 | 70.2% | 4,419 | 8.5% | 3rd |
| Aberafan Maesteg | 69,817 | 63.6% | 3,991 | 9.0% | 3rd |
| Bangor Aberconwy | 70,468 | 68.7% | 7,849 | 16.2% | 3rd |
| Caerphilly | 72,458 | 62.2% | 6,630 | 14.7% | 3rd |
| Blaenau Gwent and Rhymney | 71,079 | 59.2% | 2,687 | 6.4% | 4th |
| Neath and Swansea East | 74,705 | 60.0% | 3,820 | 8.5% | 4th |
| Montgomeryshire and Glyndŵr | 74,223 | 69.0% | 1,019 | 2.0% | 4th |
| Brecon, Radnor and Cwm Tawe | 72,113 | 72.5% | 1,692 | 3.2% | 4th |
| Merthyr Tydfil and Aberdare | 74,805 | 57.6% | 3,513 | 8.1% | 4th |
| Bridgend | 70,770 | 66.0% | 2,441 | 5.2% | 4th |
| Gower | 76,801 | 70.6% | 2,741 | 5.1% | 4th |
| Clwyd East | 76,395 | 69.1% | 2,460 | 4.7% | 4th |
| Cardiff North | 71,143 | 76.9% | 1,888 | 3.5% | 4th |
| Cardiff South and Penarth | 72,269 | 69.7% | 2,091 | 4.2% | 4th |
| Monmouthshire | 72,681 | 72.7% | 1,283 | 2.4% | 5th |
| Newport East | 76,159 | 60.9% | 1,203 | 2.6% | 5th |
| Newport West and Islwyn | 76,234 | 63.7% | 2,244 | 4.6% | 5th |
| Swansea West | 74,612 | 59.2% | 2,595 | 5.9% | 5th |
| Torfaen | 70,591 | 61.7% | 1,566 | 3.6% | 5th |
| Alyn and Deeside | 75,695 | 69.2% | 1,781 | 3.4% | 5th |
| Cardiff East | 72,463 | 64.6% | 294 | 0.6% | 6th |
Turnout as calculated by the House of Commons Library, is the total number of votes cast and not spoiled, divided by the size of the electorate.
Under section 13(b) of the Representation of the People Act 1985, a candidate gaining 5% or less of the vote share will forfeit their deposit.
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.