The basilica's current published hours are 7:00 a.m. to 8:00 p.m., with the dome open 7:00 a.m. to 6:00 p.m. in summer (March 29 to October 25, 2026) and 7:30 a.m. to 5:00 p.m. in winter. The hours page changes with the season and with papal events, so check it the week you travel.
Sundays are different. Mass is in Italian on Saturday and Sunday (Gregorian chant on weekdays), confessions run 7:00 a.m. to 1:00 p.m. and 4:00 p.m. to 7:00 p.m. instead of the weekday 7:00 a.m. to 12:30 p.m. and 4:00 p.m. to 7:00 p.m., and at noon the Pope leads the Angelus from the window above the square, which fills the square and the security line before it. On Wednesday mornings the square is set up for the 10:00 a.m. general audience and the basilica line only moves once the audience ends, usually after midday.
The dress rule is enforced at the door: no sleeveless tops, no short shorts or skirts, hats off inside. Large bags go to the cloakroom. There is no skip-the-line ticket for the basilica itself; anyone selling one is selling a tour or a dome ticket. The separate Vatican Museums entrance on Viale Vaticano is a different line and a different ticket. The page do-i-need-a-ticket-to-enter-st-peters-basilica covers the ticket question on its own.