The 2012 London Olympics are shaping up to be the most expensive games in history, according to a study by the University of Oxford. The Summer Games, which begin July 27, are also on track to be the most over-budget since the 1996 games in Atlanta. Just how deeply mired in red ink will London be by the time the Olympic flame is extinguished in August? Here, a look at the Olympic finances, by the numbers:

$13 billion
Expected sports-related cost of the London Olympics

$6.5 billion
Original estimate of the 2012 Summer Games budget

Percentage increase in the games' estimated cost, from the 2005 bid to now

Percent that the Atlanta Olympics went over budget in 1996 — the last time the games wound up costing more than twice as much as they were originally supposed to

Cost overrun, in percent, at the Beijing Olympics in 2008

Percent that the Athens Olympics ran over budget in 2004

Average cost overrun, in percent, of the sample of 17 summer and winter Olympics examined in Oxford's study

Average overrun, in percent, in the years 2000 to 2010

Average overrun, in percent, from 1968 to 2000

$37.5 billion
Projected total cost of the London Olympics, including everything from sports-related spending to security to overtime for subway train drivers, according to a Sky Sports investigation

Security guards added after the original estimate of 10,000 was determined to be inadequate

$864 million
Current estimate of the security budget, which doubled because of needs not initially spotted 

Price tag for a single outdoor sculpture called Jurassic Stones — which locals have dubbed "row of stones on sticks" — erected to greet motorists arriving at a venue for sailing events

Sources: Bloomberg, Business Insider, Daily Mail, Said Business School