Where your vote counts most.
Wales 2026 elects six members in each of 16 super-constituencies. Some seats are decided by tiny margins — those are where your vote can swing the outcome.
New to the voting system? Two-minute explainer →Projected: 3 for Reform Wales, 2 for Plaid Cymru, 1 for Welsh Labour.
Reform Wales are projected to take the last seat with a comfortable 7.0-point lead over Plaid Cymru. It would take a major shift to flip it.
The six seats
★ marginal- 1Reform36.0%
- 2Plaid29.0%
- 3Reform18.0%
- 4Labour17.0%
- 5Plaid14.5%
- 6Reform★12.0%
Next in line: Plaid at 9.67% — 2.3 points behind the marginal cut-off.
Where your vote helps most
- Plaid Cymru53%
- Reform Wales40%
- Welsh Labour22%
- Welsh Conservatives0%
Afan Ogwr Rhondda
Projected: 3 for Reform Wales, 2 for Plaid Cymru, 1 for Welsh Labour. Reform Wales are projected to take the last seat with a comfortable 7.0-point lead over Plaid Cymru. It would take a major shift to flip it.
★ marginal · cut-off 12.0%Next: Plaid 9.7%
Where your vote can swing a seat.
Each party scored 0–100% on how close it is to gaining or losing a seat in your area, normalised by the polling confidence band. Higher = your vote has more leverage.
Plaid Cymru
Some chance of swinging a seat — competitive.
Reform Wales
Some chance of swinging a seat — competitive.
Welsh Labour
Outside chance — they hold or contest from afar.
Box = YouGov 95% CI · vertical line = central estimate.
All-Wales totals.
Sum across all 16 super-constituencies = 96 seats.
How this works, in plain English
Each constituency in Wales now elects six people to the Senedd. Seats are shared out roughly in line with the votes — bigger parties win more, but smaller parties still get one or two if they have enough support. We take the latest polling for your area and work out who's likely to win each of those six seats, plus which seat is closest to changing hands. That last seat is where your vote can do the most.
See the full voting-system explainer →▸Show the maths
- Take each party's projected vote share in your constituency.
- Compute D'Hondt quotients: share / 1, / 2, / 3, …
- The six highest quotients win the six seats.
- The smallest winning quotient is the marginal seat — the one nearest to changing hands.
- For each party, we compute how close their next quotient is to that marginal cut-off, normalised by the polling confidence band. That gives the marginal-impact score.
Source: YouGov / ITV Wales Senedd MRP, April 2026. This is a projection, not a prediction.