How accurate are Polymarket election odds?

The 2024 general election, 94 races

Fifty state presidential contests, 33 U.S. Senate races and 11 governor races in OVERROUND’s record, one market each, all 94 priced by every cutoff. The first cutoff, midnight Eastern going into Election Day, is the election-morning cutoff in the tables below.

The party priced above 50 cents at midnight going into Election Day won 91 of the 94 races. The party priced above 50 cents seven days out won 93 of the 94, and the party priced above 50 cents thirty days out won 88. Three races changed favorite between the thirty-day and election-morning cutoffs, and all three resolved to the later favorite. The Republican side of the Nevada presidential contest moved from 47 to 62 cents, the New Hampshire governor race from 49 to 70 cents, and the Ohio Senate race from 48 to 60 cents.

Scope: One market per race: the Republican-side market for each of the 50 state presidential contests, 33 U.S. Senate races and 11 governor races in OVERROUND's record from the 2024 general election. Each is scored on its last traded price at midnight Eastern going into Election Day, and again seven and thirty days earlier. The favorite is whichever party was priced above 50 cents at that moment. This measures Polymarket prices, not any trader; a race with no trade by a cutoff is absent from that cutoff. A band with fewer than 30 races is shown but never quoted.

The presidency and both chambers

The three headline markets, priced at the same three cutoffs. Each row shows the market’s question and, in parentheses, the side whose price is shown. That is the side Polymarket lists first in the market, which is Yes on a Yes/No market and the first-named party on a control market.

The Trump market traded at 50.4 cents thirty days out, 66.2 cents seven days out and 59.3 cents going into Election Day. The House control market traded at 50.0 cents on its Democratic side at that last cutoff and resolved Republican.

Races by how confident the price was

Seventy-three of the 94 races had a favorite priced at 90 cents or more on election morning, and every one of those favorites won; the stated price in that band averaged 97.6% and the 95% interval on the win rate runs from 95% to 100%. The other four bands hold between one and eight races each, too few to quote, and the table shows them so the composition is visible. With 94 races, most bands are thin by construction; in 2024, 73 of them landed in the top band.

The 688 two-outcome “US Election” markets resolved November 5, 2024 to January 24, 2025

The 94 races sit inside a wider set of 688 two-outcome markets Polymarket tagged “US Election” that resolved between November 5, 2024 and January 24, 2025, with voided and disputed markets left out. Polymarket’s own sub-tags for them include State Presidential Election, Senate, Swing States, Popular Vote, Margin of Victory, Mentions and Election Night. This table scores each market’s first-listed side at each cutoff. Of the 143 markets without a price on election morning, 142 first traded after the cutoff (post-election questions) and one never traded.

Each row is its own set of markets, so a difference between rows is partly a difference in which markets were priced; the rows do not show accuracy changing as Election Day approached. Brier is the average squared gap between price and outcome, where 0.25 is what always pricing 50 cents scores. Accuracy is how often the side above 50 cents won, with markets at exactly 50 cents left out of that rate. The table below sorts the 545 election-morning markets by price.

The table does not rise steadily through the middle. The 30 to 40 cent bin resolved 18.2%, the 50 to 60 cent bin 11.1% and the 70 to 80 cent bin 57.1%, each below the bins on either side. The six bins from 30 to 90 cents hold nine to seventeen markets each, too few for one election to pin a rate. The two ends, where 292 and 87 markets sit, resolved 1.0% and 100.0% against average prices of 1.7% and 97.4%.

The 2026 midterm slate, as Polymarket lists it

As of 2026-09-22, Polymarket lists 1,177 open events under its midterms tag, carrying 11,606 markets. Polymarket’s race tags list 35 U.S. Senate race-winner events and 36 state governor race-winner events; California’s governor race is filed under the governor tag, not the midterms tag, and lieutenant governor and territory races are not counted. Each link opens the race on Polymarket. No price is quoted here for an open race; after the November 3 election resolves, this page adds the graded 2026 table built the same way as the 2024 one above.

Scope: Counts the race-winner events Polymarket lists under its midterms, governor and Senate race tags at the time of the check (35 U.S. Senate races and 36 governor races), each carrying its own party or candidate markets. Polymarket adds races and markets through the cycle, so the count is a same-day snapshot. No price is quoted for an open race; the graded table is published after the election resolves.

How to read these tables

A calibrated price is one where favorites priced at 90 cents win about 90% of the time. The stated price is the average price in the band; the win rate is how often the favorite actually won; the interval is the range that many races can pin the true rate to (a 95% Wilson interval). Fixed calendar cutoffs replace the benchmark’s distance-from-resolution horizons here because election markets resolve days or weeks after the vote, as races are called. One market per race avoids double counting. In a two-party race the Democratic market’s price is a dollar minus the Republican market’s, so scoring both would count each race twice. The same scoring, on distance-from-resolution horizons and across all of Polymarket’s markets, is the calibration benchmark; the football season graded the same way is on the NFL and college football page; how wallets rather than prices are graded is on the methodology page.

How accurate were Polymarket's odds in the 2024 election?

Across the 94 races in OVERROUND's record (50 state presidential contests, 33 U.S. Senate races and 11 governor races), the party priced above 50 cents at midnight Eastern going into Election Day went on to win 91 of them, a rate whose 95% interval runs from 91% to 99%. Seven days out the favorite won 93 of 94, and thirty days out 88 of 94. By race type, the election-morning favorite won 48 of 50 state presidential contests, 32 of 33 Senate races and all 11 governor races. Across the wider set of 688 two-outcome election markets on this page, 545 carried a price at that moment, and among those, the side above 50 cents won 92.5% of the time (markets at exactly 50 cents are left out of that rate). These are Polymarket's prices, not any trader's record.

What did Polymarket price Trump at before the 2024 election?

The market on Donald Trump winning the presidency traded at 50.4 cents thirty days before the election, 66.2 cents seven days out, and 59.3 cents at midnight Eastern going into Election Day, and resolved Yes. The market on Democrats controlling the Senate traded at 19.0 cents at that last cutoff and resolved to Republicans. The market on Democrats controlling the House traded at 50.0 cents at that cutoff and resolved to Republicans.

Does Polymarket have markets on the 2026 midterm elections?

As of 2026-09-22, Polymarket lists 1,177 open events under its midterms tag, carrying 11,606 markets. Polymarket's race tags list 35 U.S. Senate race-winner events and 36 state governor race-winner events (California's governor race is filed under the governor tag, not the midterms tag), each with its own party or candidate markets; they are listed on this page with links. No price is quoted here for an open race. After the November 3 election resolves, this page adds the graded table for the 2026 races, built the same way as the 2024 table.