London Olympics Oversold Tickets Due to a Spreadsheet Mishap

Lack of spreadsheet input validation and incorrect input lead to over-selling of seats for 2012 London Olympics swimming competitions.



> £90,000

Financial impact

London, UK




Mistake Type

Data Entry


3 months


The 2012 London Olympics were managed by the London 2012 organising committee (LOCOG). The ticket sales were performed by Ticketmaster. A spreadsheet was used to record the number of tickets sold, without regard to the individual seating layout. During this process, an employee entered the value of 20,000 for the remaining unsold tickets instead of 10,000 due to a single keystroke error. This lead to the sale of 10,000 tickets for which physical seats were not available. The cheapest ticket for the synchronised swimming event were £20 going up to £75 in the main stadium.


Before Christmas, during reconciliation of number of tickets sold against the final layout of the events and the seating chart, it became apparent that the events were oversold to the tune of 10,000 seats.

LOCOG and Ticketmaster contacted ticket holders for overbooked seats and offered them alternatives. For instance, for those who applied for tickets for other sports, but were not successful, an upgrade was offered at no extra cost. This also included a refund for the difference between the sold event and the substitute. Decision varied based on the timing of events in an attempt to minimize distruption to travel plans.

Luckily the error was discovered before a planned online exchange designed to allow fans to swap unwanted tickets rather than sell them went online. That allowed LOCOG a certain flexibility in resolving the discrepancies.

Spreadsheet Error

The tickets were sold in phases. When a phases would end the results would be populated in the spreadsheet with the remaining number typed in. The spreadsheet did not provide a control that the values should be decreasing, or some kind of validation against the total number of tickets

total tickers = tickets sold + tickets remaining

A one character typing error lead to the number entered in the remainign tickets cell to be increased from the correct amound of 10,000 to 20,000 thous creating 10,000 fictitiuous tickets.


LOCOG provided the following announcement:

As a result of finalising the seating configurations in our venues and reconciling the millions of Olympic and Paralympic ticket orders against the seating plans for around 1,000 sporting sessions, we have discovered an error in seats available in four Synchronised Swimming sessions ... In December we contacted around 3,000 customers who had applied for tickets in the four sessions during the second-round sales process. We are exchanging their synchronised swimming tickets for tickets in other sports that they originally applied for.

Exact numbers for the monetary losses are not provided. However, if we take the figure of at average £30 (£20 compared to £75) difference and the number 3,000 customers, we can arrive at the estimate of £90,000 at the low end. Considering that the highest number of cusomters affected is 10,000 we could have a much higher number, but it has been indicated that some customers were offered, and accepted, tickets for other events.

It goes without saying that in addition to the purely financial impact such a mishap comes as a big blow to the reputation of the organizers.

Timeline of events

The error happened in the summer of 2011 between the first and second round of ticket sales.


Early Summer, 2011

First round of ticket sales commences. The number of remaining seats in the spreadsheet is correct.


Mid Summer, 2011

The spreadsheet is updated with the first number sales numbers. Instead of entering the correct amount of 10,000 an operator by mistake entered 20,000.


Late Summer, 2011

In the second round of sales the remaining tickets are sold. The events are sold out, including 10,000 tickets ficticious seats that did not exit.


Dec, 2011

LOCOG and Ticketmaster contacted ticket holders for overbooked seats and offered them alternatives.


Summer, 2012

Events proceeded where ticket holders attended the alternative events.


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