How much does it cost to trade on Polymarket?

Polymarket charges approximately 2% of net winnings on resolved contracts. There are no deposit fees for crypto transfers, but withdrawal transactions incur gas fees on the Polygon network, typically under $0.10. Limit orders that add liquidity may receive reduced fees. The effective cost depends on the contract price at entry.

How much does Kalshi charge per trade?

Kalshi charges a per-contract fee, typically ranging from 1 to 2 cents per contract on entry and exit. There is no additional fee embedded in the odds themselves. Contracts are priced in cents from 1 to 99, and the fee applies regardless of the contract price. Volume-based discounts may apply for active traders.

Which prediction market has the lowest fees?

Polymarket generally costs less on a percentage basis for high-probability contracts, since its 2% fee applies only to winnings. Kalshi's flat per-contract fee can be cheaper on low-probability, high-payout trades. Metaculus is free because it uses reputation points instead of real money. The optimal platform depends on the specific trade.

How Prediction Market Fees Work: Platform Cost Comparison

Q: How do prediction market fees compare to sportsbook vig?

Sportsbooks embed 4-10% vigorish directly into the odds, making the true cost invisible to most bettors. Prediction markets charge explicit fees, typically 1-3% of the trade value. On an equivalent wager, prediction market fees are usually lower, but sportsbooks offer deeper liquidity and wider event coverage for sports.

Prediction market fees determine how much of your profit you actually keep. Every platform charges differently — Polymarket takes a percentage of winnings, Kalshi charges per contract, and community platforms like Metaculus are free. The fee structure you trade under directly affects your breakeven probability and expected return.

How Much Do Fees Cost on a $100 Trade?

The dollar impact of fees varies significantly depending on the platform, the contract price, and whether the trade wins. Here is the cost breakdown for a $100 position across the three major platforms:

Platform	Fee Structure	Cost on $100 at 50%	Cost on $100 at 80%	Cost on $100 at 20%
Polymarket	~2% of net winnings	~$1.00	~$0.50	~$4.00
Kalshi	Per-contract fee (1-2 cents)	~$1.00-$2.00	~$1.00-$2.00	~$1.00-$2.00
Metaculus	Free (reputation-based)	$0	$0	$0

The pattern is clear: Polymarket’s percentage-based fee scales with the profit margin. Buying a contract at 80 cents means only 20 cents of potential profit per contract, so the 2% fee on winnings is small in absolute terms. Buying at 20 cents means 80 cents of potential profit, and 2% of that is considerably larger.

Kalshi’s per-contract fee is constant regardless of the contract price. This makes Kalshi relatively cheaper for low-probability, high-payout trades and relatively more expensive for high-probability, low-payout trades.

The Odds Reference fee calculator lets you compare the cost of any trade across platforms in real time.

How Does Polymarket’s Fee Structure Work?

Polymarket charges approximately 2% on net winnings from resolved contracts. The fee is assessed at settlement, not at the time of trade. If a contract does not resolve in your favor, you pay no fee beyond the cost of the contract itself.

Worked example: You buy 200 contracts at $0.40 each, spending $80 total. The event occurs, and each contract pays $1.00. Your gross payout is $200, your net profit is $120, and Polymarket’s 2% fee on that profit is $2.40. You receive $197.60.

Additional costs on Polymarket include:

Gas fees on withdrawals: Polygon network fees are typically negligible (under $0.10), but bridging to Ethereum mainnet can cost $5-20 depending on network congestion
Spread costs: The bid-ask spread on thinner markets acts as an implicit fee, sometimes exceeding the explicit 2%
USDC conversion: If you start with fiat currency, conversion to USDC through an exchange involves its own fees

Polymarket’s fee structure rewards high-conviction trades on high-probability events, where the profit margin is small but the fee is proportionally tiny.

How Does Kalshi’s Fee Structure Work?

Kalshi charges a per-contract fee on each side of a trade — both entry and exit. The standard fee ranges from 1 to 2 cents per contract, though the exact amount depends on the contract type and the trader’s volume tier.

Worked example: You buy 100 contracts at $0.40 each, spending $40 plus roughly $1.00 in entry fees. The event occurs, and each contract pays $1.00. Your gross payout is $100, minus roughly $1.00 in exit fees. Total fee cost: approximately $2.00. Net profit: $58.00.

Kalshi’s cost structure has several implications:

Flat cost regardless of outcome price: Whether you buy at $0.05 or $0.95, the per-contract fee is the same. This makes Kalshi comparatively expensive for high-probability trades with thin margins
Fee on both sides: Unlike Polymarket’s settlement-only fee, Kalshi charges on entry and exit, so you pay even if you sell before resolution
No crypto overhead: Kalshi accepts USD directly via bank transfer or debit card, eliminating the conversion and gas costs associated with crypto platforms

For traders making many small trades, Kalshi’s flat fee structure is predictable and easy to model. For large positions on high-probability events, the per-contract fee can exceed Polymarket’s percentage-based alternative.

How Do Prediction Market Fees Compare to Sportsbook Vig?

Sportsbooks and prediction markets both charge for access to event-outcome markets, but the mechanisms are fundamentally different.

Cost Type	Prediction Markets	Sportsbooks
Fee visibility	Explicit — stated percentage or per-contract	Hidden — embedded in the odds
Typical cost	1-3% of trade value	4-10% vig (implied by odds)
When charged	Settlement or trade execution	Built into every line
Who pays	Winning side only (Polymarket) or both sides (Kalshi)	Every bettor, win or lose
Fee on losing trades	None (Polymarket) or minimal (Kalshi)	Full vig embedded in the line

A standard sportsbook line of -110 on both sides of a binary event implies a combined probability of 104.8% — the extra 4.8% is the vig. The bettor pays this cost through worse odds, whether they realize it or not.

Prediction markets make the cost explicit. A Polymarket contract trading at its true probability has a 2% fee applied only if you win. On an apples-to-apples comparison, the prediction market trader keeps more of their profit on winning trades.

However, sportsbooks offer advantages that offset their higher costs: deeper liquidity on sports events, more granular prop markets, and promotional offers (sign-up bonuses, boosted odds) that can temporarily eliminate the vig entirely.

Our data across both verticals shows where these cost structures converge and diverge. The Odds Reference dashboard tracks prediction market prices alongside historical sportsbook odds for shared events.

What Hidden Costs Should Traders Watch For?

Beyond the stated fees, several implicit costs affect real returns:

Spread costs. The bid-ask spread on any order book represents an immediate cost. On a liquid Polymarket market, the spread might be 1-2 cents. On a thin Kalshi market, it can be 5-10 cents. A 5-cent spread on a $0.50 contract is effectively a 10% round-trip cost, dwarfing any explicit fee.

Opportunity cost of locked capital. Prediction market contracts can take months or years to resolve. Capital tied up in a $0.90 contract earning $0.10 of profit has a very different risk-adjusted return than the same capital deployed elsewhere.

Currency conversion. Polymarket requires USDC, which means fiat-to-crypto conversion fees (typically 0.5-1.5% on major exchanges). Kalshi accepts USD directly, avoiding this cost entirely.

Withdrawal timing. Kalshi withdrawals to a bank account take 1-3 business days. Polymarket withdrawals to an external wallet are near-instant on Polygon but can take longer and cost more if bridging to Ethereum.

For a detailed breakdown of how fees affect any specific trade, use our fee calculator to model the exact cost before entering a position.

How Should Fee Structure Influence Platform Choice?

The optimal platform depends on your trading profile:

High-probability trades ($0.70+): Polymarket’s percentage-based fee is small in absolute terms. Kalshi’s flat per-contract fee is comparatively more expensive here
Low-probability, high-payout trades ($0.05-$0.30): Kalshi’s flat fee is cheaper in percentage terms. Polymarket’s 2% of a large profit adds up
Frequent small trades: Kalshi’s predictable per-contract fee is easier to model. Polymarket’s settlement-only fee means no cost on losing trades
Non-US traders or crypto-native users: Polymarket avoids banking friction entirely. Kalshi requires US residency and a bank account

Cross-referencing prices across platforms before trading can also reveal fee-adjusted arbitrage. If Polymarket prices an event at $0.62 and Kalshi prices it at $0.65, the 3-cent spread may or may not survive after accounting for each platform’s fee structure. Our platform comparison and Polymarket vs Kalshi breakdown cover these dynamics in detail.

Key Takeaways

Polymarket charges ~2% of net winnings at settlement; Kalshi charges 1-2 cents per contract on entry and exit — each structure favors different trade types
Hidden costs (spreads, currency conversion, locked capital) often exceed explicit fees on thin markets
Prediction market fees are typically 1-3% of trade value, compared to 4-10% vig embedded in sportsbook odds
The fee calculator models exact costs for any trade across platforms before you commit capital
Platform choice should factor in fee structure alongside liquidity, event coverage, and geographic access