Two years ago the choice in the prediction market space was pretty straightforward. Polymarket was the crypto-native platform Americans weren’t meant to touch while Kalshi was the regulated US exchange that played by the book. Fast forward to today and there are multiple other prediction market platforms like Rothera, Predictdotfun, Opinion, Limitless etc that are looking to bite away at the market share. Despite competition ramping up, Kalshi and Polymarket are by far the leaders in terms of volume, number of trades and open interest. 

The line from two years ago, however, has mostly dissolved. Polymarket now runs a CFTC-licensed US arm and despite Kalshi fighting roughly a dozen states in the US over whether sports contracts count as gambling, the latest numbers on combined trading volume between the two platforms hit $47.5 billion in the month of June alone this year. That’s more than triple the roughly $14 billion a month US sportsbooks averaged in 2025, per Pew Research Center.  

Kalshi vs Polymarket at a Glance 

Fees Compared 

Kalshi charges on nearly every trade. Polymarket, for most of its life, charged almost nothing. That gap narrowed hard on March 30, 2026, when Polymarket switched on taker fees across nearly every category except geopolitics and world events, which stay free. Both platforms now use a probability-weighted curve, so the fee is highest on coin-flip markets near 50¢ and shrinks toward the extremes. 

Kalshi’s taker fee follows 0.07 × price × (1 − price) per contract, which tops out around 1.75 cents on a 50¢ contract and falls off fast on lopsided markets. Post limit orders instead and the maker fee drops to about a quarter of that. Polymarket flipped the logic: makers pay nothing at all and even earn a slice of taker fees back through its rebate program, while takers pay a category rate that peaks at 50¢ and lands anywhere from $0.75 per 100 shares on sports to roughly $1.75 on crypto. Its US-regulated arm runs a simpler flat model, a taker fee around 0.3% with a maker rebate. 

Here’s what a $100 position at 50¢ (200 contracts or shares) actually costs to enter:

The pattern is clear enough. On sports and most non-crypto markets, Polymarket International is cheaper to take, sometimes by half. On crypto they’re roughly even. And if you can sit on a limit order and wait, Polymarket’s zero maker fee is tough to beat, while Kalshi still clips you a little. What that table hides is everything around the trade: Kalshi funds in dollars for free over ACH, while Polymarket means buying USDC first, which can carry a 2% to 4% on-ramp fee depending on the route you take.

What you can bet on 

Both platforms offer thousands of event-based contracts across several broad categories to choose from. That said, when you look at the trading volume metrics between the two, it becomes evident which markets each platform specializes in. For instance, when you look at the split in volume in sports based contracts between the two platforms, Kalshi currently holds a dominance of 71.5%. On the other hand, when it comes to contracts within the politics category, Polymarket is the go to platform with 97.3% dominance. 

That split can actually be traced back to the strategies employed by both platforms. Over the past year, eventhough both platforms landed the NHL as the first major league to back prediction markets,  Kalshi has leaned harder into sports, signing the Chicago Blackhawks as the first North American pro team to partner with a prediction market, adding Madison Square Garden, and running a World Cup blitz that included sponsoring the reigning-champion Argentine Football Association. Meanwhile Polymarket built its name on the 2024 US elections and never really gave up its lead on political event markets.

The sharper difference is what each one is allowed to touch. Kalshi’s contracts are listed based on whatever’s within CFTC purview. This includes categories such as sports, economics, rates, elections, weather, entertainment, crypto prices. Polymarket’s international platform does not follow these guidelines and hence lists markets on war, military strikes and regime change that no regulated US platform would list. If you want to trade the outcome of a live global crisis the hour it breaks, Polymarket usually has the market first.  

US legality & who can trade

On paper, both Kalshi and Polymarket US are CFTC-regulated and legal in all 50 states and Washington DC. In practice, a wall of state challenges has turned that into a moving target, and almost all of it centers on sports.

Kalshi holds the first federal license the CFTC ever granted an event-contract exchange, dating to 2020, and it operates in dollars with the kind of oversight a US brokerage user would recognize. But since late 2025 more than a dozen states have argued its sports contracts are unlicensed gambling, and the courts have split. Kalshi won a landmark ruling at the Third Circuit on April 6, 2026, the first appeals court to say the CFTC has exclusive jurisdiction, and it won a preliminary injunction in Tennessee in February. It lost ground elsewhere. A New York federal judge refused to block state enforcement on July 8, 2026, and courts in Maryland, Arizona, Nevada and the Sixth Circuit have leaned toward the states. Minnesota went further and passed an outright ban that takes effect August 1, 2026. The CFTC has now sued nine states to defend its turf, and most observers expect the fight to reach the Supreme Court. 

Polymarket’s US story is different. Its main international platform is geo-blocked for Americans, and using a VPN to get around that isn’t permitted. This remains to be the case even after the platform has been in active discussions with CFTC to lift the ban on US-based users. To trade legally in the US, Polymarket bought a CFTC-licensed exchange, QCX, and stood up a separate Polymarket US app in December 2025. It’s legal, it’s regulated, and it’s walled off from the global liquidity pool, which is exactly why its volume is a fraction of the international side. American traders essentially pick between a regulated venue with thinner books and an offshore one they’re not supposed to use. 

Trading volume & market share

Kalshi is the current volume leader, and at the time of writing it isn’t close. Data from Artemis shows that total weekly volume across all platforms hit a new all time last week topping out at $16.6 billion. When you look at the split, however,  Kalshi still dominates with 66.9% market share and Polymarket at 25.3%. The 2026 FIFA World Cup lit the whole sector up. Kalshi’s single World Cup winner market drew north of $800 million in bets, and combined monthly volume across both platforms jumped 75% in June alone. Total volume across prediction markets in May were already at new highs. However, the World Cup catapulted the monthly volume from around $28 billion to $51.7 billion in June. 

Source: Artemis

Those numbers deserve a second look before anyone treats them as settled. Volume counts every contract that changes hands, not the money actually sitting in the market, so the headline totals run well above the capital in play. Trackers don’t measure it uniformly and they cover different sets of platforms, so the totals shift from one source to the next. 

There’s also a wash-trading question hanging over Polymarket’s history. A Columbia University study estimated that roughly a quarter of its past volume may have been wash trades, which the researchers tie to airdrop farming on a no-KYC, zero-fee platform, and whether the new fee structure cleans that up will only show over the coming months. 

Custody, wallets & payouts

This is the cleanest line between the two, and it comes down to who holds your money. Kalshi runs like a traditional exchange. You fund in dollars by bank transfer or debit card, your cash sits in segregated accounts under CFTC rules, and USDC deposits are safeguarded through Coinbase Custody. Winnings land in your dollar balance and withdraw back to your bank. Kalshi does place a short security hold on deposited funds first, generally around two days after a debit or bank transfer settles, with wires, PayPal and Venmo carrying none, and that hold applies only to what you put in, not your earnings, which can be withdrawn right away. Worth knowing: segregation is a real protection in a bankruptcy, but Kalshi isn’t a bank, and event contracts aren’t FDIC-insured.

Polymarket hands custody to you. Funds live in your own wallet or in the market’s smart contract on Polygon, denominated in USDC, and the platform never holds your keys. Withdrawals are near-instant and cost fractions of a cent in gas. That self-custody is the appeal for crypto-native users and the risk for everyone else, because there’s no FDIC or SIPC backstop and no regulator to call if something goes wrong. Settlement mechanics differ too. Kalshi resolves against named third-party sources written into each contract’s rules and handles disputes through a regulated channel. Polymarket leans on the UMA oracle and a market integrity committee, with contested outcomes escalating to a token-holder vote that can run two to four days. Most markets settle without drama on either side, but Polymarket’s resolution disputes have occasionally gotten loud. 

Which Should You Choose? 

If you’re in the US and you’re looking for a simple, regulated platform, Kalshi is the answer. Dollars in, dollars out, 1099 tax forms, a real regulator, no wallet to manage. You’ll pay a bit more per trade and trade a slightly narrower list of event contracts but that’s the price of the guardrails at the moment. 

If you’re crypto-native and fee-sensitive, Polymarket International is hard to pass up, assuming you can access it legally where you are. The maker fee is zero, most non-crypto categories undercut Kalshi, geopolitics contracts are free, and the market selection is the widest anywhere. The catch is custody, taxes, and the US access question all land on you. 

FAQs

Is Kalshi or Polymarket better?

It depends on factors such as location and cost. Users from the US can find a regulated exchange in Kalshi. However, for those looking to access more niche markets with lower fees, Polymarket may be the way to go. 

What’s the difference between Kalshi and Polymarket?

Kalshi is a CFTC regulated exchange that runs on US dollar, much like how a brokerage does. Polymarket on the other hand is an onchain platform on Polygon that settles in USDC and you hold your own funds. 

Which has higher trading volume, Kalshi or Polymarket? 

Currently Kalshi is in the lead by a long shot. Kalshi’s monthly trading volume in June 2026 closed at $33 billion compared to Polymarket’s $14.5 billion.    

Is Polymarket legal in the US like Kalshi? 

Only Polymarket US, built on the CFTC-licensed exchange it bought, is legal in the US at the moment. Its international platform remains geo-blocked for Americans. 

Can US residents use both Kalshi and Polymarket?

US residents can access Kalshi but Polymarket international remains out of reach for users from the US. 

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