The new calculated grading system, introduced due to Covid-19, shows an increase of 4.4 per cent on average across all subjects.
The Department of Education says today's results are "stronger" than a normal year but that the grades estimated by teachers were higher again before the calculated grades system brought them down.
Overall, 16.9 per cent of grades have been lowered from what had been given by teachers.
H1 grades of 90 per cent and above, equivalent to the old A1, are up 3.3 per cent at Higher Level and 1.7 per cent at Ordinary Level.
There has also been a three per cent rise in H1 grades in Higher-Level Irish, or over 800 more students picking up top marks compared with last year.
In English the increase was 1.3 per cent, or nearly six hundred more, and in Maths there was a 2 per cent rise at higher level.
In Maths and Irish, the numbers graded at Foundation level has roughly halved.
In Art, Economics, Accounting, Business and Home Economics the share of H1s at Higher Level has at least doubled, while in Music, they rose from 4.3 per cent to 13.
The Minister for Education Norma Foley says the decision to provide students with calculated grades was taken with their best interests at heart, saying they this year's class have shown enormous resilience.
"This has been a particularly challenging and difficult year for the class of 2020, but they have been remarkable and I want to acknowledge them for their intense determination and focus and their patience."
Despite concerns that the calculated grades system would lead to grade inflation the Teachers Union of Ireland (TUI) is hopeful the system is fair and has also praised students for their perseverance during an extremely difficult time.
TUI President, Martin Marjoram said: "We are reassured. We do note that a number of grades have come down as part of the standardisation process but not a huge number and I think it's a testament to things, that teachers were pretty accurate with what they estimated and that they were generous towards their students as well."
Following the release of results, a free anonymous 24/7 text service is available to provide immediate support to Leaving Certificate students.
If they feel upset or overwhelmed about their results, or the CAO, they can free-text the word TALK to 50808.
