How does the NBA Draft Lottery work? Complete guide to rules, history, odds, ping pong balls and more

For a few NBA teams each season, ping pong balls matter more than basketballs.

The NBA Draft Lottery can chart the course of a franchise for years to come, and under the current format, the fate of teams is even more unpredictable than ever before.

When a can't-miss prospect comes along, the lottery can change the landscape of the NBA. It's what sent LeBron James to Cleveland, Anthony Davis to New Orleans and Victor Wembanyama to San Antonio — and the system isn't going away anytime soon.

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Here's a complete guide to the NBA Draft Lottery, including the rules and process.

What is the NBA Draft Lottery?

The NBA Draft Lottery includes every non-playoff team and determines which teams receive the top four picks in the NBA Draft. Before 2019, the lottery only determined the top three picks. 

The NBA holds a draft lottery largely to prevent extreme tanking. If a can't-miss prospect is entering the draft and no lottery is in place, the league's worst teams are incentivized to lose as much as possible to have the NBA's worst record and earn the No. 1 pick.

Under the current lottery system, there is no difference between having the worst record or third-worst record. The Pistons learned this in 2024, when they had the NBA's worst record at 14-68 but didn't win any of the four lottery drawings and landed the No. 5 pick.

MORE: NBA Draft lottery odds for 2025

When is the NBA Draft Lottery?

The NBA typically holds the draft lottery in the second or third week of May. 

While the day varies by year, the lottery is often held a handful of weeks after the regular season ends and serves as a lead-in to a playoff game. The NBA Draft is typically more than a month after the lottery takes place.

How does the NBA Draft Lottery work?

The NBA Draft Lottery determines which teams receive a top-four pick in the NBA Draft. After the order of the top four is settled, the remaining teams fall in line between fifth and 14th based on regular season record. 

Every non-playoff team's first-round pick is entered into the NBA Draft Lottery. If one of those teams has traded its pick to another team without protections, the acquiring team will select wherever that pick lands, thus opening up the possibility of a playoff team being involved in the lottery. For example, the Spurs owned the Raptors' 2024 first-round pick, so San Antonio knew it would select wherever Toronto fell in the lottery in addition to its own pick. If a lottery team has traded its pick to another team with protections, the lottery result could determine whether the acquiring team receives the pick. 

Ping pong ball system

Ping pong balls numbered 1-14 are put into the machine and drawn four times. There are 1,001 possible combinations of ping pong balls; 1,000 are assigned to teams, with the worst teams receiving the most combinations. The remaining combination is invalid and would result in the lottery being redrawn. 

This process takes place behind closed doors with select media members and a representative from each team watching. The lottery is conducted by accounting firm Ernst & Young.

Once the lottery is conducted, the sealed results are handed to the NBA's deputy commissioner to be read on the live broadcast. 

NBA Draft Lottery changes over the years

The NBA Draft Lottery format has changed multiple times over the years. From 1966-84, the No. 1 pick was determined by a coin flip between the worst team from each conference, by record. 

Starting in 1985, the NBA switched to a lottery system to discourage tanking. For the first five years, each non-playoff team had the same chance of winning. The draft order was determined by randomly selecting an envelope and finding out which team was inside it. The Knicks were the first winner of the lottery and selected Patrick Ewing.

By 1990, the NBA moved to a weighted system that gave the teams with the worst records better odds. After the Magic moved up 10 slots to win the No. 1 pick in 1993, the odds were adjusted in 1994 to ensure the worst teams had an even higher chance of winning the lottery.

The most recent reform came in 2019, when the NBA made the odds a bit more even to again discourage tanking after the 76ers were scrutinized for intentionally tearing down their roster in the 2010s and fielding, in some cases, historically bad teams with an eye toward lottery success. That change also expanded the number of picks determined by the lottery from three to four. 

NBA Draft Lottery representatives 

Each team in the lottery sends a representative to the live announcement production. That representative could be anyone from the general manager, to the owner, to a player or even a family member of the owner. 

Some teams are superstitious about their lottery representative. The Cavaliers believed Nick Gilbert, the son of owner Dan Gilbert, was good luck for the franchise after he served as the team's representative when it landed the No. 1 pick in both 2011 and 2013. 

In addition to the in-studio representatives, each team can send a representative to watch the lottery drawing behind closed doors.

Most surprising NBA Draft Lottery results

The 1993 Magic hold the record for worst odds by a team that won the No. 1 pick.

Orlando entered the lottery with a 1.52 percent chance of earning the top choice after a 41-41 season but jumped every team ahead of it, forcing the NBA to reform the weighting system the following year. The Magic traded the pick to the Warriors on draft night, allowing Golden State to walk away with Chris Webber and Orlando to land Penny Hardaway.

Here is every team that won the No. 1 pick with odds of six percent or lower:

* — Traded to Warriors on draft night.

NBA Draft Lottery conspiracy theories

The first true NBA Draft Lottery has long been subject to conspiracy theories surrounding the Knicks' win, which allowed them to select Patrick Ewing.

At the time, all seven non-playoff teams had even odds, and the winner was determined by simply commissioner David Stern picking random envelopes. Some theorize the envelope was altered in some way to allow Stern to identify which belonged to the Knicks so he could give the struggling franchise a chance to choose the top player in the draft.

Accounting firm Ernst & Whinney, which still conducts the lottery as Ernst & Young, was used by Knicks ownership at the time, adding another layer to the theory.

Because the lottery is now held behind closed doors, other conspiracy theories have surfaced over the years. Some believed the Cavaliers' three wins in four years after losing LeBron James were too good to be true, while others objected to the Pelicans' unlikely win in the Zion Williamson sweepstakes while Anthony Davis was on the way out of New Orleans.

No NBA Draft Lottery conspiracy theories have been proven, to say the least.

Tanking: How teams try to improve odds

As long as teams with worse records have better odds than teams better records, some franchises are going to try to angle their way to the best possible lottery position.

That process can involve trading their best players or sitting them under the guise of injury or load management — and, to be clear, tanking does not mean the players on the court are trying to lose games; it simply means teams are intentionally not putting the best possible group on the court.

When the 76ers were regularly near the top of the lottery in the mid-2010s, they largely had a barren roster after trading pieces including Jrue Holiday, Evan Turner, Spencer Hawes and Thaddeus Young. Philadelphia was only an average team with those players, so GM Sam Hinkie, hired in 2013, decided blowing up the operation and contending for top-3 picks was a better strategy than regularly hovering near .500 without a realistic chance of competing for championships. 

That doesn't mean every bad team is tanking. The Pistons, who won just 14 games in 2023-24, entered that season believing they were going to take a step forward. They played their best players and simply didn't meet expectations. 

The NBA has tried to address tanking by flattening out the lottery odds and punishing teams for holding healthy players out of games, but the long-term rewards that can come from winning the lottery still incentivize teams to lose if their chances of meaningfully contending are slim.