How Does the Indy 500 Work? Explaining the Indianapolis 500

The Indianapolis 500, or Indy 500, is one of the largest and most famous races on the planet. Since 1973 the race is held on Memorial Day weekend at the Indianapolis Motor Speedway. The 2025 race will be the 109th in history and the event routinely pulls in more than 300,000 fans to the stands (not to mention a global television audience).

But how does the race work? From qualifying for the Indy 500 to the race itself, we're breaking it down.

What is the Indy 500? Is it a NASCAR Race?

The Indianapolis 500 is an IndyCar Series race and therefore has no connection to NASCAR whatsoever. Some individuals have raced in both IndyCar Series and NASCAR before, but there is no affiliation between the two.

In fact, there are a plethora of differences.

NASCAR is stock car racing. The vehicles look similar to production cars and weigh about 3,200 lbs. They use a 5.8-liter V8 engine and typically reach speeds in the 200 mph range.

IndyCars look more like a Formula 1 car, being lower to the ground with an open wheel. The cars use 2.2-liter twin-turbo V6s and can usually hit 220+ mph. They are much lighter than stock cars, topping out around 1,600 lbs.

How Does Indianapolis 500 Qualifying Work?

Indy 500 qualifying is a multi-day process that determines the 33-car starting grid. Every driver completes a four-lap speed run on day one, but the total time isn't used, nor is the best lap speed. Rather, the average of the four laps is used. The 12 fastest advance to day two, but the top 30 are locked into the Indy 500.

On day two, those dozen compete again for a chance at the 'Fast Six.' Those six then run again, this time for the pole position. If there are more than 33 entrants, the slowest remaining drivers compete in a last chance qualifier in an attempt to secure one of the final spots.

The Rules of the Indianapolis 500

The Indianapolis 500 features 33 drivers in 11 rows of three. The positions are determined during the qualifying process described above. Things begin with a rolling start and pace laps.

Laps are counted under green and yellow flags. Depending on the number of yellow flags (caution periods), the race typically lasts around three hours. Yellow flags come out when there is a crash, or debris on the track, or other hazardous track conditions. In extreme cases, the race may be red-flagged until the safety of the racers can be maintained (well, as much as it can be in an IndyCar race).

During the race, drivers will take multiple pit stops to either add fuel, change their tires or make other technical adjustments. Calculating a fuel consumption strategy is absolutely key, as the fewer pit stops made, the quicker one can complete the race.

Each IndyCar uses Firestone Firehawk tires and the pit crew typically changes all four during each stop. However, some drivers opt for changing just two because it is much faster. But a lot of those decisions depend on the stage of the race and the conditions of the track.

Passing is permitted, but it doesn't work the same way it does in NASCAR. IndyCar tracks aren't as wide and the aerodynamics of the IndyCar are much different than a stock car. Due to these elements, passing in IndyCar is something accomplished by the thinnest of margins. It's also worth noting that blocking is an illegal maneuver.

The Indianapolis 500 ends after 200 laps around the 2.5-mile oval track. The winner will receive the Borg-Warner Trophy and typically celebrates by chugging some milk in victory lane (although this isn't always the case).