There were 39 620 000 Facebook users in United Kingdom in December 2018, which accounted for 57.5% of its entire population.
The majority of them were women - 52.3%.
People aged 25 to 34 were the largest user group (10 000 000).
The highest difference between men and women occurs within people aged 55 to 64, where women lead by 1 900 000.