Counting the votes

Londoners’ votes for the Mayor of London, London Assembly Constituency member and London Assembly London-wide member contests will be verified and counted over the two days after polling day on Thursday 2 May. The verification of ballot papers from all three contests will take place on Friday 3 May, and the votes cast for all three contests will be counted on Saturday 4 May. 

Votes at previous GLA elections have been counted electronically at three count centres. In 2024, votes will be counted by hand at 14 Assembly Constituency count venues across London.  

The Greater London Returning Officer will announce the results of the Mayoral and 11 London-wide Assembly Member contests at City Hall on Saturday 4 May. The 14 Constituency London Assembly Member contest results will be announced by the relevant Constituency Returning Officers at their counts on Saturday 4 May. 

How are Mayoral results calculated?

The Mayor of London is elected by the ‘first past the post’ system.

This means the candidate with the most votes is elected as Mayor of London.

How are London Assembly (constituency) Member results calculated?

The 14 London Assembly Constituency Members are elected using the ‘first past the post system’. 

This means the candidate in each constituency with the most votes is elected as a London Assembly (constituency) Member. 

How are London Assembly (London-wide) Member results calculated?

The 11 Assembly London-wide Members are elected using a form of ‘proportional representation’: this system is used to ensure the overall Assembly reflects how London voted.

This means that these Assembly seats cannot be allocated until the constituency results have been announced. 

The 11 seats are allocated using a mathematical formula – the ‘Modified d’Hondt Formula’.

The formula uses the votes cast in the London Assembly London-wide Member contest and takes account of the number of London Assembly Constituency Member seats that each political party has already won.

11 rounds of calculations then take place to fill the 11 vacant Assembly Member seats, with the party or independent candidate with the highest result at each round being allocated the seat.

Seats won by parties are allocated to party candidates in the order they appeared on the relevant party’s list of candidates.

Find out more about the London Assembly.

How does the Modified d'Hondt formula work?

The formula uses 11 rounds of calculations to allocate the 11 London-wide seats.

It divides the number of London-wide Assembly votes for each party or candidate by the number of Constituency Assembly Member seats already won, plus one.

From the second round onwards, the number of London-wide Assembly Member seats won by parties up to that point is added to the number of Constituency Assembly Member seats it won.

At each of the 11 rounds, the party with the highest calculated total is assigned a London-wide Assembly Member.

This ensures that that the overall make-up of the Assembly is proportionate to how Londoners have cast their votes in the London-wide Assembly contest.