The figures, published by the Joint Council for Qualifications, cover A-level entries from students in England, Wales and Northern Ireland.
The proportion of A-level entries awarded top grades is down on last year but still remains above pre-pandemic levels, national figures show.
Hundreds of thousands of students across the country received their A-level results on Thursday in a year when ministers and the exams regulator in England aimed to return to pre-pandemic grading.
More than a quarter (27.2%) of UK entries were awarded an A or A* grade, down by 9.2 percentage points on last year when 36.4% achieved the top grades.
However, this was still higher than in 2019 – the last year that summer exams were taken before the pandemic – when 25.4% of entries were awarded A or A* grades.
The overall pass rate – the proportion of entries graded A* to E – has fallen to 97.3% this year, which is lower than 2022 (98.4%) and the pre-pandemic year of 2019 (97.6%).
The A*-E pass rate is at its lowest level since 2008 when it stood at 97.2%
The figures, published by the Joint Council for Qualifications (JCQ), cover A-level entries from students in England, Wales and Northern Ireland.
In England, exams regulator Ofqual had said this year’s A-level results would be lower than last year and they would be similar to those in 2019 as part of efforts to return to pre-pandemic grading.
It comes after Covid-19 led to an increase in top grades in 2020 and 2021, with results based on teacher assessments instead of exams.
In Wales, results are expected to be “broadly midway” between those awarded in 2022 – the first year students sat exams following the pandemic – and 2019.
In Northern Ireland, results are expected to return to pre-pandemic levels next year.
Overall, the proportion of UK entries awarded the top A* grade this year has fallen by 5.7 percentage points to 8.9% compared with 14.6% in 2022, but it is higher than when it stood at 7.7% in 2019.
Boys have pulled ahead of girls at the top grade this year after female entries were in front for the last three years, with A* grades at 9.1% for the former compared with 8.8% for the latter.
Girls continued to outperform boys at A* and A but the gender gap has narrowed again this year.
A total of 3,820 students in England alone scored three A*grades, according to separate figures from exams regulator Ofqual.
This is down from 8,570 last year, but up from 2,785 in 2019.
Many A-level students in Wales and Northern Ireland were given advance information about topics to expect in their exam papers this summer but students in England were not given the same support.
Ofqual said it built protection into the grading process in England this year to recognise the disruption that students have faced, which should have enabled a student to get the grade they would have received before the pandemic even if the quality of their work is a little bit weaker due to disruption.
The cohort of students who are receiving their A-level results did not sit GCSE exams and were awarded teacher-assessed grades amid the pandemic.
Geoff Barton, general secretary of the Association of School and College Leaders (ASCL), said: “The proportion of students achieving the top A-level grades has fallen sharply this year, not as a result of underperformance, but because the grading system has been adjusted in the wake of the pandemic so that the distribution of grades in England is similar to 2019.
“This adjustment is a return to normality after the pandemic which necessitated the use of different approaches to grading.
“Whatever the rationale, however, it will feel like a bruising experience for many students, as well as schools and colleges which will have seen a sharp dip in top grades compared to the past three years.
“It is important to remember that these students also suffered the disruption of the pandemic, and this will have impacted particularly on those from disadvantaged backgrounds.”
He added: “We would urge students who are disappointed by their grades not to panic but to talk to their teachers about the options available to them and we wish all the young people receiving their results today every success for the future.”
Margaret Farragher, chief executive of the JCQ, said: “This year’s results recognise the fantastic achievements of students across the country. They have worked incredibly hard throughout the pandemic period to achieve these well-earned grades.
“The 2023 results show that students are well equipped to continue their studies or move into apprenticeships or employment. ”
Pupils in Scotland received their results last week and the Scottish Qualifications Authority figures showed that the Higher pass rate was down from last year but it remained above 2019 levels.