Quick answer
Prediction markets traded $109 million in the last 24 hours across Kalshi and Polymarket. Open interest stands at $1.26 billion across 149,750 live markets. The dashboard below reads the venues' public APIs, every open market, refreshed every 15 minutes. Volume, open interest, and the top markets, on one page. Free, no signup.
Prediction markets became a real asset class. The data stayed scattered: one number on a venue homepage, another on a Dune dashboard, a third in a screenshot on X, none of them measuring the same thing.
This page fixes that. Every open market on Kalshi and Polymarket, summed the same way, on one screen. Volume. Open interest. The markets doing the most business right now.
Prediction markets traded $109M in the last 24 hours across Kalshi and Polymarket, with $1.26B of open interest standing across 149,750 live markets. Polymarket is the larger venue right now, at 50.5% of tracked 24-hour volume.
24h volume
$109M
All tracked venues
Open interest
$1.26B
Standing positions
Live markets
149,750
Open right now
Kalshi · 24h
$53.9M
Contracts at $1 notional
Polymarket · 24h
$55.1M
On-chain USDC volume
Polymarket · 7d
$206.3M
Trailing week
24h volume share
Top markets by 24h volume
Both venues, ranked together
| # | Market | Venue | 24h volume | Open interest |
|---|---|---|---|---|
| 1 |  LoL: KT Rolster vs Dplus KIA (BO5) - LCK Playoffs | Polymarket | $8M | $4M |
| 2 |  Fed Decision in September? | Polymarket | $7M | $21.4M |
| 3 | Omega European Masters Winner | Kalshi | $4.4M | $7.4M |
| 4 | LoL: Anyone's Legend vs LGD Gaming (BO5) - LPL Playoffs | Polymarket | $4.2M | $2M |
| 5 | Fed decision in Sep 2026? | Kalshi | $2.5M | $25.7M |
| 6 | BTC price on Sep 4, 2026 at 5pm EDT? | Kalshi | $1.9M | $1.5M |
| 7 |  Republican Presidential Nominee 2028 | Polymarket | $1.7M | $9.2M |
| 8 | US Open Men's Singles Winner | Kalshi | $1.6M | $16.3M |
| 9 | Seyboth Wild vs Varillas | Kalshi | $1.4M | $773k |
| 10 |  Clarity Act (H.R.3633) signed into law in 2026? | Polymarket | $1.4M | $5.1M |
| 11 | Indiana St. vs Purdue | Kalshi | $1.4M | $1.4M |
| 12 |  Bitcoin above ___ on September 4? | Polymarket | $1.3M | $1.2M |
| 13 |  2026 Men’s US Open Winner (Tennis) | Polymarket | $1.1M | $1.7M |
| 14 | BTC price on Sep 4, 2026 at 9am EDT? | Kalshi | $1.1M | $591k |
| 15 | How low will BNB get in September? | Kalshi | $1M | $1,797 |
Volume by venue
Live where a venue publishes data
| Venue | 24h volume | 7d volume | Open interest | Live markets | Data status |
|---|---|---|---|---|---|
| Polymarket | $55.1M | $206.3M | $353.4M | 31,523 | Full venue, via public API |
| Kalshi | $53.9M | · | $911.3M | 118,227 | Full venue, via public API |
| Robinhood Prediction Markets | · | · | · | · | No public market-data API; volume disclosed only in earnings |
| Crypto.com Sports & Events | · | · | · | · | No public market-data feed |
| PredictIt | · | · | · | · | Public prices API, but no volume or open-interest fields |
| Predict.fun | · | · | · | · | On-chain venue; not yet aggregated here |
| Novig | · | · | · | · | No public market-data feed |
| ProphetX | · | · | · | · | No public market-data feed |
Source: Kalshi and Polymarket public market-data APIs, aggregated across every open market and refreshed every 15 minutes. Kalshi contracts are valued at $1 notional; methodology below.
How much volume do prediction markets trade?
The tiles above are the live answer, computed from every open market on both venues. On August 13, 2026, the day this page shipped, the 24-hour count stood at $151 million. That was an ordinary Thursday in August: no election, no Fed decision, no championship game. Around those, daily volume multiplies.
Two numbers matter, and they answer different questions. Volume is flow: how much traded over a window. Open interest is commitment: the value of positions still standing, money that stays in the market until the question resolves. A venue can print huge volume on day-trading churn. Read open interest to see how much conviction is actually parked there.
Is Kalshi or Polymarket bigger?
Kalshi usually wins the volume race. Its sports contracts trade and settle daily, and that flow compounds. Polymarket runs deeper open interest on its political and macro questions, and its on-chain settlement means every dollar is publicly verifiable. The share bar above settles the argument for today. It will look different next week.
The head-to-head on fees, liquidity, and market coverage is in our best prediction market apps comparison. The short version: serious traders stop picking a side. They hold accounts at both and route each trade to the better price, through a prediction markets trading terminal built to do exactly that.
How is this data measured?
The same way for both venues, or the comparison is fiction. Every number on this page is read from the venues’ own public market-data APIs: every open market, summed, refreshed every 15 minutes.
| Kalshi | Polymarket | |
|---|---|---|
| Source | Public trade API, every open event, roughly 10,000 of them, no sampling | Public gamma API, every active event ranked by weekly volume |
| Units | Contracts at their $1 settlement notional, the same convention Kalshi uses for its own published totals | Dollars (USDC), as reported on-chain |
| Open interest | Sum of open contracts at $1 notional | Venue-wide figure from Polymarket’s global open-interest endpoint |
| Known gaps | The public API carries no trailing-7-day field, so the 7d column is Polymarket-only | The API stops paging past its top 2,000 events, so events under $2,000 of weekly volume fall outside the sum. The lost tail is under $2,000 per event per week. |
The $1 notional convention
A Kalshi contract pays $1 if it settles yes. Valuing traded contracts at $1 notional is how Kalshi reports its own milestones, and it is the only convention that makes a contract count comparable to Polymarket’s dollar volume. Cash changing hands per contract is the trade price. That is lower, and it cannot be reconstructed in aggregate from public data. Every serious cross-venue tracker makes this same choice; we just say it out loud.
Institutions that need the same feed raw, over REST and websockets with historical depth, get it through the Kairos prediction market API.
Which prediction markets publish data?
Fewer than you’d think. Kalshi and Polymarket publish full market-level feeds, which is why they are the two venues this dashboard can measure honestly. The rest of the field runs from prices-only APIs to nothing at all, and a venue that publishes nothing has volume claims nobody can check. The table above lists them, and what each one withholds.
Analysts, journalists, and answer engines pull their numbers from the venues they can verify. Kalshi and Polymarket publish full feeds, so the record is theirs, and the venues that publish nothing get left out of it. When a venue opens a real feed, this page will read it.
How do traders actually use this data?
Volume is tradeable information. A market climbing this board is where news is breaking and liquidity is arriving: spreads tighten, size becomes fillable, and the price starts meaning something. Open interest building under a flat price means someone is positioning quietly. The traders on our prediction market leaderboard live on these signals, and the Polymarket whale tracker shows the individual fills behind them.
Watching the board is the start. Acting in the same second is the point. Kairos was built for exactly that, and our best prediction market terminals comparison shows the whole field. Sub-second data, one book across venues, real order types. See you in the order books.