Home Field Advantage, Measured: 12,293 US League Games and 13,327 Soccer Matches on Polymarket

Polymarket titles a US league game with the away team first: "Bills vs. Texans" is the Bills at the Texans, and the Texans are the second outcome of the moneyline. Its event data carries the same fact as a field, marking each team home or away. On a sample of 300 settled NFL, NBA, MLB, NHL, WNBA and college football games, that field marked the second outcome as home in 281 and the first in none; the other 19 carried no marking.

Soccer runs the other way. A Polymarket soccer match is three markets, and the draw market names the home team first: "Will Manchester United FC vs. Manchester City FC end in a draw?" is Manchester United at home. On a sample of 200 matches across ten competitions, the event data agreed 200 times. The script, the sample and its output are published with the study.

With the home team identified, how often it wins is a count of settled results, and whether bettors price it correctly is a comparison of what they paid with how often their side won.

The US count takes one full-game moneyline per game from each league's first game on record to September 13, 2026: 2,770 NBA games, 4,778 MLB, 2,425 NHL, 1,050 college football, 687 NFL and 583 WNBA. All-Star and 4 Nations games are left out, and so is any game whose market settled 50-50, which is how an NFL tie settles.

The soccer count takes matches with all three result markets settled, from November 21, 2025: 13,327 club matches, every one of which resolved exactly one Yes. National-team matches, club friendlies and one-match super cups are left out by the competition Polymarket files them under, because a friendly or a super cup is often played away from either team's home ground.

The pricing half uses the large-trade alerts from April 2, 2026, the first day the alert table's outcome labels are trustworthy (0xinsider.com/research/favorite-longshot-bias-polymarket-sports documents why): 104,703 buys of $1,000 or more on US moneylines and on soccer team-to-win markets, $2.43 billion in stakes across 5,108 markets. Rates carry plain binomial half-widths; pricing intervals resample markets.

In the NBA, home teams won 55.2% of 2,770 games, with a half-width of 1.85 points. The NHL came in at 54.2%, the WNBA at 54.4%, MLB at 53.4% over 4,778 games and the NFL at 52.1%.

Read those as a few points above an even split, not as a large edge. A home team at 54% wins about eight games in fifteen. The rates held from year to year: MLB came in at 53.3% in 2025 and 53.5% so far in 2026, the NBA between 54.7% and 55.8% in each calendar year, the NHL between 52.5% and 55.2%.

NFL home teams won 52.1% of 687 games from August 8, 2024, and the half-width is 3.74 points, so the interval runs from about 48% to 56% and includes an even split. By calendar year it was 51.3% over 304 games in 2024 and 53.7% over 296 in 2025.

An NFL season is 272 regular-season games, so no single season settles the question, and this sample spans parts of three. What the data supports is that NFL home field was worth at most a few points over this stretch, and possibly nothing.

College football home teams won 64.7% of 1,050 games, the largest home rate here by more than nine points. It splits by date: 58.9% over 700 games in 2025, and 76.3% over the 350 games of 2026 so far.

The 2026 games are only the opening weeks of a season, so that figure is not a season rate, and this data does not separate conference games from the rest. Take the 2025 rate as the steadier number and the early-season rate as a partial one.

In 13,327 club matches, the home side won 43.6% of the time, with a half-width of 0.84 points, the away side 30.2% and 26.2% ended level. The home side wins about 13 matches in a hundred more often than the away side.

Because a soccer match can be drawn, the home rate is not comparable with the US leagues directly. Among matches with a winner, the home side won about 59% of the time, a larger edge than any US pro league shows.

Twenty-six competitions have 200 or more complete matches. Home sides won most often in Peru's Liga 1, 51.7%, the Champions League, 50.5%, and La Liga, 49.1%. They won least often in the Japan J2 League, 35.1% with away sides winning just as often, and in the Egyptian league and the Eredivisie, both near 37%.

The Premier League sits low at 37.5% over 275 matches, with 32.4% drawn. Each competition's home rate carries a half-width of five to seven points, so most of these differences are inside the noise; the table below lists every competition with its draws and away wins.

Large buyers of the home side came in 0.28 points behind the price over 57,239 buys, with a market-resampled interval from minus 3.59 to plus 3.00. Buyers of the away side came in 0.66 behind over 47,464, from minus 3.94 to plus 2.83. Both sides paid about what their chances were worth.

MLB, with the most markets, is the clearest: home buyers paid 57.8 cents and won 57.5% of the time, away buyers paid 53.9 cents and won 53.7%, each within about a quarter of a point. Soccer's away side came in 2.68 points behind, inside an interval fifteen points wide. The NBA and NHL samples come from the final regular-season weeks and the playoffs, about 200 markets each, and football buys are too few to read.

So the few points of home advantage are already in the price. A bettor who adds a home bonus on top of a Polymarket price is counting it twice.

Split by price, home underdogs, home sides bought under 50 cents, came in 1.05 points ahead over 12,979 buys and plus 8.6% on the dollar. Away favorites came in 2.06 points behind over 26,265 buys and minus 5.4% on the dollar.

That is the direction the betting folklore about home underdogs points, and none of it clears zero: the home underdog interval runs from minus 3.53 to plus 5.44 and the away favorite interval from minus 6.39 to plus 2.10.

It does not say why teams win at home, whether travel, rest, crowds or officiating; it counts results. It also does not separate neutral-site games, such as NFL international games or bowl games, from true home games; the home team is the one Polymarket's event data marks.

The pricing half comes from particular stretches: MLB from April to mid-September, the NBA and NHL from their final regular-season weeks and playoffs, the WNBA season, and club soccer. NFL and college football buys number 183 and 141, too few to read, so the NFL pricing question waits for this season.

Markets that settled on Polymarket but have no recorded result in 0xinsider's database are not counted; for soccer result markets since June that is about 2% of closed markets. Every position is scored as held to settlement at the buyer's price, before fees.

Home advantage is real in every league measured here and small in every pro league: two to five points above an even split in the US, and a larger share of decided matches in soccer. It is also priced. Large bettors on both sides paid about what their chances were worth, so the home team is not a bet in itself.

Use the rates to check a price, not to adjust one. An NBA home team at 50 cents against an equal opponent is priced as if home court were worth nothing, which the data says is wrong. A home team priced at 55 cents in the same game already carries the edge.

Every game on the league boards, 0xinsider.com/sports/nfl, 0xinsider.com/sports/nba, 0xinsider.com/sports/mlb, 0xinsider.com/sports/nhl, 0xinsider.com/sports/wnba, 0xinsider.com/sports/college-football and 0xinsider.com/sports/soccer, lists both teams with their Polymarket prices. The event page's Markets section adds the spreads, totals and props, and its Top holders tab lists the wallets holding each side with the grade each has earned.

The whale alerts feed at 0xinsider.com/whale-alerts shows every large trade as it fills, marked BUY or SELL, with the wallet's grade. The guide at 0xinsider.com/learn/how-to-bet-on-nfl-polymarket covers the NFL markets game by game, and 0xinsider.com/research/point-spreads-polymarket covers spreads.

Every number on this page comes from one read-only run of a set of queries against the production database at 21:44 UTC on September 13, 2026. The query text, the raw output, the market-level export, the bootstrap output, the home-team check against Polymarket's event data and the competition list are public at github.com/0xinsider/research, under polymarket-sports-markets, in the files whose names carry the word home.

The US universe is one settled full-game moneyline per game in the NFL, NBA, MLB, NHL, WNBA and college football whose title lists its two outcomes in order. The soccer universe is club matches with the draw market and both team-to-win markets settled. The pricing universe is every large-trade alert for a Polymarket buy on those markets, settled after the trade, at 2 to 98 cents, from April 2 to September 13, 2026.

Expect the counts to grow, the NFL most of all as its season runs. The pro-league home rates should hold within their half-widths.