Home field advantage, measured: 11,581 US league games and 13,327 soccer matches on Polymarket

Home teams won more often than away teams in every league measured here, from 53.7% in MLB and the NFL to 64.4% in college football. Polymarket already charges for it. In 104,445 large bets on one side of a game, the home side cost more and won more, by almost exactly the gap in price, as the chart below shows.

So don't add a home bonus on top of a Polymarket price. The market has already counted it once, and counting it again is the mistake this study measures.

The chart below has every league. That is a few points above an even split, not a large edge: a home team at 54% wins about eight games in fifteen and loses the other seven.

NFL home teams won 53.7% of 566 games from September 6, 2024. The half-width is 4.11 points, so the interval runs from 49.6% to 57.8% and includes an even split.

An NFL season is 272 regular-season games, so no single season settles the question, and this sample spans parts of three. MLB's home teams came in at the same 53.7% over eight times as many games, and the chart below shows what that buys: an interval about a third as wide. Baseball's small home edge is the better-measured one. For the NFL, the data supports a home edge worth a few points over this stretch, and possibly nothing.

College football home teams won 64.4% of 985 games, the largest home rate here by nearly nine points. The chart below splits it by year, and the split matters.

Trust the 2025 rate over the 2026 one. The 2026 games are the opening weeks of a season, when many games pair a major program at home with a smaller visitor, so that figure is not a season rate. This data also does not separate conference games from the rest. Bowl games and other neutral-site games are left out.

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 won 30.2% and 26.2% ended level. The home side wins about 13 matches in a hundred more often than the away side.

Don't compare that home rate with the US leagues directly, because a soccer match can be drawn. 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.

Large buyers of the home side came in 0.28 points behind the price over 57,130 buys, with a market-resampled interval from minus 3.65 to plus 3.06. Buyers of the away side came in 0.63 behind over 47,315, from minus 4.15 to plus 2.80. Both sides paid about what their chances were worth.

Soccer's away side came in 2.69 points behind, inside an interval fifteen points wide. MLB, with the most markets, is the clearest case: home buyers paid 57.8 cents and won 57.5% of the time, and away buyers paid 53.9 cents and won 53.8%. Each side landed within about a third of a point of its price.

Split by price, home underdogs (home sides bought under 50 cents) came in 0.95 points ahead over 12,933 buys, plus 8.5% on the dollar. Away favorites came in 1.98 points behind over 26,158 buys, minus 5.3% on the dollar.

That is the direction the folklore about home underdogs points, and none of it clears zero. The home underdog interval runs from minus 3.65 to plus 5.58, and the away favorite interval from minus 6.23 to plus 2.20. The folklore gets the sign right and the size wrong: there is no edge here big enough to trade on.

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, and the data says that is wrong. A home team at 55 cents in the same game already carries the edge.

The rates are steady enough to lean on. In the chart below, no big-four league's home rate moved three points from one calendar year to the next, so last season's rate is a fair guide to this one.

It does not say why teams win at home, whether travel, rest, crowds, or officiating; it counts results. For US games the home team and the venue are ESPN's. Soccer's home team is the one Polymarket's draw market names first, and soccer matches at a neutral venue are not separated out.

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, about 200 markets each, the WNBA season, and club soccer. Football has almost nothing, as the chart below shows, 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.

Polymarket usually titles a US league game with the away team first: "Bills vs. Texans" is the Bills at the Texans. Matched against ESPN's schedule, 239 of the 12,203 settled NFL, NBA, MLB, NHL, WNBA, and college football games ESPN lists named the home team first, 110 of them NFL games in 2024 and 109 MLB games, most in April 2025. So this study takes the home team from ESPN's schedule for every US game, whichever team Polymarket named first.

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 traders price it correctly is a comparison of what they paid with how often their side won. The settlement matched ESPN's final score on 12,190 of the 12,203 games ESPN lists. Most of the few misses paired a market with a neighboring game of the same series, and they are left out.

The US count takes one full-game moneyline per game from each league's first game on record to September 13, 2026. Left out, as the chart below counts: preseason and spring training games, All-Star and summer league exhibitions, games ESPN marks as played at a neutral site, a second Polymarket market for the same game, and 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 (the favorite-longshot bias study documents why): 104,445 buys on US moneylines and on soccer team-to-win markets, $2.42 billion in stakes across 5,071 markets. The smallest recorded buy was about $3,000 until July 2, 2026 and $10,000 after. Rates carry plain binomial half-widths; pricing intervals resample markets.

On September 14, 2026, the day after publication, we matched every US game in the study to ESPN's schedule and recounted. The first version read the second-named team of every US game as the home team and counted every settled game. That put preseason games, spring training, All-Star and summer league exhibitions, neutral-site games and 39 duplicate markets in the sample, and it swapped the home and away teams in 239 games.

The recount moved every US league rate by less than two points, as the chart below shows, and left each conclusion in place except one: the NFL's home edge is not the smallest on its own; MLB's is the same. The pricing half barely moved, because the buys it counts start in April 2026, after the titles changed. The query, the ESPN match, and the recount scripts are published beside the original run.

The moneyline is where most of a game's trading happens: more than half of each league's game volume in the chart below. It is also the price every league board shows. The NFL, NBA, MLB, NHL, WNBA, college football and soccer boards list each game with both teams' Polymarket prices.

On Pro, a game's event page adds a Markets board with the spreads, totals and props and each family's volume, and the wallets holding each side with their grades. The large-trade feed shows fills of $10,000 or more with each wallet's grade, live on Pro and 24 hours behind without it.

The soccer figures come from one read-only run of a set of queries against the production database at 21:44 UTC on September 13, 2026. The US figures and the pricing come from the recount on September 14, 2026, a read-only export matched game by game to ESPN's public schedule, and the volume by league from a read-only query at 12:20 UTC on October 11, 2026.

The query text, the raw output, the ESPN match, the recount and pricing scripts with their outputs, the market-level export, 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 chart below sums up the checks those files run.

The US universe is one settled full-game moneyline per regular-season, postseason or play-in game in the NFL, NBA, MLB, NHL, WNBA, and college football, at the home team's venue on ESPN's schedule. 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.