How a pope is chosen, from the empty see to white smoke

A conclave is the one moment in Vatican life that draws more people to St Peter’s Square than Christmas, and hardly anyone knows how it works inside. I’ll walk you through it using the rules the Holy See publishes and what happened at the last one, in May 2025. And since this is a travel guide, I’ll finish with what you can and can’t see if you happen to be in Rome.

How is the pope chosen? The vote in the Sistine

The Sistine Chapel has hosted every conclave since 1878. On entering, each cardinal swears on the Gospels to keep the proceedings secret, and from then on the voting is written. Each ballot is printed with Eligo in Summum Pontificem and a space for the name, and each elector carries his to the altar in full view of the others.

Election takes at least two thirds of the votes of those present. In 2025, with 133 electors, the magic number was 89. There are four ballots a day, split between morning and afternoon. After three days without agreement there’s a day’s pause for prayer and discussion, and if deadlock continues, eventually only the two leading names can be elected, they lose their own vote, and two thirds is still required. You can see the room itself on any ordinary visit, and I cover it in depth in my guide to the Sistine Chapel.

Who votes, and when does the conclave start?

The vote belongs to cardinals who haven’t turned 80 on the day the see falls vacant, with a ceiling of 120 electors on paper. In 2025 there were 133, above that figure, and all of them voted. No other church office and no civil power can take part.

The clock comes from a 2013 rule by Benedict XVI. The cardinals wait fifteen full days for those still travelling, can start earlier if everyone is there, and must begin within twenty days at most. In 2025 they set the date on 28 April and the conclave opened on 7 May, after the Pro eligendo Papa Mass in St Peter’s. Throughout, they sleep at the Domus Sanctae Marthae, next to the basilica.

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What happens when a pope dies or resigns

As soon as a pope dies, the Camerlengo officially confirms the death, seals the study and bedroom and informs the Cardinal Vicar of Rome. That opens the vacancy of the see. Almost every post in the Curia lapses, except the Camerlengo himself and the Major Penitentiary, who keep the ordinary business going, and the Fisherman’s Ring and the lead seal of apostolic letters are cancelled. The cardinals hold nine consecutive days of funeral rites, the novendiales.

With a resignation the start is different but the rest is the same. Canon law only asks that it be free and properly made known, and nobody needs to accept it. Benedict XVI announced his on 11 February 2013 and the see fell vacant on 28 February at 20:00. From then on, the rules were exactly as after a death.

In 2025 the timeline ran like this. Francis died at 07:35 on 21 April at Santa Marta, the funeral was held in the square on the 26th and he was buried at Santa Maria Maggiore, outside the Vatican. His tomb is open to visitors, and I place it alongside the others in where the popes are buried.

The smoke, how it’s made and how to read it

After each ballot, or each pair when two are held back to back, the scrutineers burn the papers before the cardinals leave the chapel. There are two stoves. A cast-iron one from 1939 burns the ballots, and a second, added in 2005, produces the colour with cartridges. Black uses potassium perchlorate, anthracene and sulphur, white uses potassium chlorate, lactose and Greek pitch. The smoke travels up a flue of about 30 metres and out through a copper pipe a metre and a half tall on the roof.

Black means no pope. White means there is one, and the bells of St Peter’s confirm it. In 2025 there was black smoke on the evening of 7 May, and the white came at 18:07 on the 8th, on the fourth ballot. Then the senior cardinal deacon announces the name from the balcony and the new pope gives his first blessing. Who emerged, and what’s known about him, is in who Pope Leo XIV is.

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What can a visitor see during a conclave?

Many visitors assume otherwise. What you won’t see is the Sistine Chapel, which shuts to the public before it begins. In 2025 that happened on 28 April, nine days ahead, and visits to the Vatican Gardens and the Via Triumphalis necropolis were suspended too. The Museums as a whole weren’t on the list of closures.

What you can see is the chimney. It’s on the Sistine Chapel roof, to the right of the basilica as you face it from St Peter’s Square, and since voting happens morning and afternoon, the smoke comes out as each round ends. If it’s white, I’d stay put, because there’s a gap between the smoke and the announcement. The balcony is the Benediction Loggia, at the centre of the façade, and I explain how to spot it in the façade and balcony of St Peter’s.

Outside a conclave, which is nearly always, there’s nothing to look at on the Sistine roof. What’s worth your time is the room inside, with the ceiling and the Last Judgement, which is where the voting really happens.

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