The move means the Rupert Murdoch-owned tabloid now costs 10p less than its main tabloid rival the Daily Mirror, which is priced at 40p, and 5p less than the Daily Star.
The price gap between the Sun and the mid-market titles is even more marked. The paper is 20p less than the Daily Mail.
The Daily Mirror and the Daily Mail have raised their cover prices over the past year as their stockmarket-listed parent companies have attempted to shore up revenues.
Underlining its ability to take the pain, The Sun will continue to pay retailers in England based on a cover price of 35p.
The Sun was previously priced at 35p in England and Wales with the exception of Scotland, London and the South East where it was already at 30p.
It made an aggressive price cut last September in London and the South East, from 35p to 20p, before increasing it to 25p in May and to 30p in July.
Describing today's price cut as "credit crunch defying", The Sun also trumpeted six months in a row of year-on-year circulation increases and said it now outsells the combined total of the Daily Mirror, the Daily Star and the Daily Express.
Roland Agambar, marketing director at The Sun, said: "At a time when many companies, including our competitors, are constantly cutting costs to the detriment of their product, we are constantly looking to improve our product and increase the value we give to our readers."
The Sun's June circulation stood at 3,089,321, down 1.9% from May. However its six-month average circulation was 3,120,512, up 1.54% year on year.
.jpg)
.jpg)