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 |
| Mid and South Pembrokeshire | 76,820 | 71.6% | 2,917 | 5.3% | 3rd |
| Gower | 76,801 | 70.6% | 2,741 | 5.1% | 4th |
| Clwyd East | 76,395 | 69.1% | 2,460 | 4.7% | 4th |
| Newport West and Islwyn | 76,234 | 63.7% | 2,244 | 4.6% | 5th |
| Newport East | 76,159 | 60.9% | 1,203 | 2.6% | 5th |
| Clwyd North | 76,150 | 67.4% | 3,713 | 7.2% | 3rd |
| Alyn and Deeside | 75,695 | 69.2% | 1,781 | 3.4% | 5th |
| Merthyr Tydfil and Aberdare | 74,805 | 57.6% | 3,513 | 8.1% | 4th |
| Neath and Swansea East | 74,705 | 60.0% | 3,820 | 8.5% | 4th |
| Swansea West | 74,612 | 59.2% | 2,595 | 5.9% | 5th |
| Montgomeryshire and Glyndŵr | 74,223 | 69.0% | 1,019 | 2.0% | 4th |
| Ceredigion Preseli | 74,063 | 69.8% | 16,045 | 31.1% | 1st |
| Cardiff West | 73,947 | 70.2% | 4,419 | 8.5% | 3rd |
| Pontypridd | 73,743 | 61.8% | 4,963 | 10.9% | 3rd |
| Rhondda and Ogmore | 73,557 | 57.8% | 5,290 | 12.4% | 3rd |
| Caerfyrddin | 72,683 | 73.4% | 16,362 | 30.7% | 2nd |
| Monmouthshire | 72,681 | 72.7% | 1,283 | 2.4% | 5th |
| Dwyfor Meirionnydd | 72,533 | 69.6% | 23,110 | 45.7% | 1st |
| Cardiff East | 72,463 | 64.6% | 294 | 0.6% | 6th |
| Caerphilly | 72,458 | 62.2% | 6,630 | 14.7% | 3rd |
| Cardiff South and Penarth | 72,269 | 69.7% | 2,091 | 4.2% | 4th |
| Brecon, Radnor and Cwm Tawe | 72,113 | 72.5% | 1,692 | 3.2% | 4th |
| Cardiff North | 71,143 | 76.9% | 1,888 | 3.5% | 4th |
| Blaenau Gwent and Rhymney | 71,079 | 59.2% | 2,687 | 6.4% | 4th |
| Wrexham | 70,964 | 66.4% | 2,960 | 6.3% | 3rd |
| Bridgend | 70,770 | 66.0% | 2,441 | 5.2% | 4th |
| Torfaen | 70,591 | 61.7% | 1,566 | 3.6% | 5th |
| Bangor Aberconwy | 70,468 | 68.7% | 7,849 | 16.2% | 3rd |
| Llanelli | 69,895 | 62.8% | 9,280 | 21.1% | 3rd |
| Aberafan Maesteg | 69,817 | 63.6% | 3,991 | 9.0% | 3rd |
| Ynys Môn | 52,415 | 69.7% | 10,418 | 28.5% | 3rd |
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.