NBA Draft Lottery Odds History: From Coin Flips to Ping-Pong Balls

15 November 2026

For nearly two decades, the right to draft first in the NBA came down to a coin flip between two teams. From 1966 through 1984, the clubs with the worst records in each conference took part in the toss, and the winner picked No. 1. Since 1985 the league has used a lottery, and the odds have been rewritten several times, most recently to make losing less rewarding.

From coin flips to the first draft lottery

The coin-flip era was simple. Only two teams had a chance at the top pick: the worst team in the East and the worst team in the West. Everyone else slotted in behind them by record. That gave a team with the league's worst record no better than even odds of first choice, but it also gave a franchise that had finished a little better in its own conference the same shot as the true cellar-dweller, so long as it was the worst team in its half of the league.

The league's own history of the lottery, published by the NBA, marks 1985 as the year that changed. The first NBA Draft Lottery that year involved seven non-playoff teams, and each had equal odds of landing the No. 1 pick. The idea was to remove the incentive to finish with the league's worst record, since a bad finish no longer guaranteed anything special and a slightly better one did not rule out the top choice.

Equal odds had an obvious flaw, and it shaped everything that followed. A team that won a handful more games than the league's worst club had exactly the same chance at the first pick as that club. Fans and executives could see the system treated very different seasons identically. It rewarded no one for being bad, but it also gave a team that had been bad for years no extra relief. Nearly every later change to the lottery has been an attempt to balance those two concerns: discourage deliberate losing while still giving the weakest teams the best shot at a franchise-altering player.

How the early lottery changed in the 1980s and 1990s

The format did not stay put for long. In 1986 the NBA narrowed the lottery so that it determined only the order of the first three selections. Before that, the drawing had set the order for every lottery pick. After the change, the three winners would be drawn and the remaining non-playoff teams would pick in order of record. That is a significant shift for a team's planning, because a bad team that missed the top three could count on the next-best slot that its record earned rather than seeing its position scrambled across the lottery.

The bigger overhaul came at the end of the decade. In October 1989, the Board of Governors expanded the lottery to 11 teams and introduced weighted odds based on regular-season finish, as The Record reported in its history of the lottery. For the first time, the worse a team's record, the better its chance at the top pick. The equal-odds principle of 1985 was gone.

The 1990 draft put that weighted idea into practice with a ball system. CBS Sports describes the format as using 66 lottery balls, with the worst team receiving 11 balls and the best lottery team receiving one. The arithmetic fits an 11-team lottery: 11 balls for the worst team, 10 for the next, and so on down to one, which adds up to 66. A team's chance was therefore its share of the balls, so the worst team held 11 of 66, or one-sixth. That is a real edge over the best lottery team's one ball, but it is hardly overwhelming. The worst club still failed to win the top pick more often than it won it.

That is the weakness the league kept coming back to. A weighting that leaves the worst team with roughly a one-in-six shot at No. 1 does little to compensate a franchise for a miserable season. Within a few years, the Board of Governors went back to the formula.

The modern ping-pong-ball drawing

The mechanics of today's lottery are easier to follow once you see how they turn a team's odds into something physical. The current format, as described by the Denver Nuggets' history of the lottery on NBA.com and by Sporting News, works like this:

• The drawing uses 14 ping-pong balls, numbered 1 through 14.
• Four balls are drawn, and together they form a four-digit combination.
• That setup yields 1,001 possible four-ball combinations.
• Of those, 1,000 are assigned to the lottery teams in proportion to their odds.
• The one remaining combination is invalid. If it comes up, the balls are drawn again.

The reason for the odd extra combination is arithmetic. Picking four balls from 14 produces 1,001 distinct groups, but the league wants to hand out a round 1,000 so that odds translate cleanly into percentages. Each assigned combination is worth one-tenth of one percent. A team with a 14 percent chance holds 140 combinations, and a team with a 0.5 percent chance holds just five. When the invalid one appears, the league simply redraws, and no team is ever advantaged or hurt by it.

For readers trying to make sense of a lottery night, that conversion is the most useful habit. When a broadcast lists a team's odds, multiply by 10 and you have the number of four-digit combinations it owns out of 1,000. Seeing the odds as combinations also explains why a team with long odds can still win. Five combinations is a tiny share, but it is not zero, and every draw is independent of the standings once the combinations are assigned.

The 1994 reset and the road to today

The first major correction to the 1990 weighting came in November 1993. The Board of Governors approved a new format effective with the 1994 NBA Draft Lottery, according to the Nuggets' history on NBA.com. It increased the worst team's chance of the No. 1 pick to 25 percent and cut the best lottery team's chance to 0.5 percent. Under the 66-ball system, the worst team had held about 17 percent, so the change gave the league's bottom club a considerably larger edge, and it nearly erased the top pick as a realistic outcome for the best team in the lottery.

That structure held for more than two decades. It made the worst record the single most valuable position in the lottery, and the odds fell steeply from there. That steepness fed the long-running debate over tanking, the idea that a team might deliberately lose to climb toward the top of the lottery. A 25 percent shot for one team and a sliver for others made the gap between finishing last and finishing a few spots higher very large.

The league responded in September 2017, when the Board of Governors changed the odds so the teams with the three worst records each had a 14 percent chance of winning the No. 1 pick, as AP News reported. Under that plan, finishing last no longer improved a team's top-pick odds over finishing third from the bottom. The reward for sinking to the very bottom shrank, which was the point of the reform.

The change also reached beyond the top pick. The 2019 NBA Draft was the first to use the reform that expanded the lottery drawing to determine the first four picks, rather than just the first three. A team could no longer be sure of a particular landing spot once it entered the lottery, because more of the early order was now left to the balls. In practical terms, a club with the worst record could fall further than it could have under the earlier system.

From a coin flip between two teams to a four-ball drawing that sets the first four picks, the lottery has moved steadily toward spreading the odds more evenly across the weakest teams. For anyone following a lottery night, the simplest way to read it is to take each team's percentage, turn it into combinations out of 1,000, and remember that the first four picks, not just the first one, now depend on the draw.