Prediction market fees compared – how trading costs differ across platforms
Two prediction markets can quote the same 50¢ contract and still leave you with different trading costs. The fee formula is only the starting point.
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By Barbara Pazur
Order type, spreads, slippage, market category, and funding costs can all change what you actually pay. This article compares U.S. fee structures using current information from Kalshi, Polymarket, and OG.com.
Disclaimer: In this article, Polymarket means Polymarket US. It’s a separate, U.S.-regulated, dollar-based product from the global crypto platform at polymarket.com.
This article is for informational purposes only and should not be construed as financial or investment advice. Past performance does not guarantee future results.
Why fee structure matters more than headline rates
A quoted percentage doesn’t always tell you the cost of a trade. Platforms may calculate fees from the contract price, number of contracts, order type, or even the market category.
Kalshi’s standard taker formula, for example, uses a 0.07 coefficient. That doesn’t mean you simply pay 7% of the amount spent. If you take 100 contracts at 50¢, the current standard fee is $1.75.
How the order executes can change the number as well. A trade that fills immediately may pay a taker fee, while a resting order may face a lower maker fee, no maker fee, or even receive a rebate depending on the platform.
Then there are costs outside the published trading fee. A wider bid-ask spread or a worse execution price can easily cost more than a small difference between two fee formulas.
For any prediction market platform comparison, fees are most useful when you compare the same order type, contract price, and size.
How prediction market fees work
An event contract fee structure can be based on several things.
Kalshi and Polymarket use price-sensitive formulas for standard taker trades. The fee is highest around the middle of the contract-price range and falls as the price gets closer to 0¢ or $1.
Other prediction markets use fixed per-contract pricing. OG.com, for example, uses separate pricing for some U.S. crypto, foreign exchange, commodities, and equity-index markets.
The market category can therefore change the fee even on the same platform.
Maker vs. taker fees explained
A taker order fills immediately against liquidity already available in the order book.
A maker order rests at your chosen price until another trader matches it. If it never fills, there’s no completed trade.
Platforms can price those two order types very differently. Kalshi charges its standard taker fee on immediately matched orders, while maker fees apply only in designated markets.
Polymarket charges standard taker fees but currently pays standard makers a rebate instead of charging them a maker fee.
OG.com also distinguishes between immediate and resting orders. The imit orders let you set your price and wait for a match. The fee is 1.75% and is charged only if the order is accepted and the trade completes. An unfilled limit order doesn’t incur a trading fee.
So maker vs. taker fees in prediction markets can change the economics of the same trade even before you look at spreads or execution.
How to calculate total cost of a prediction market trade
The total cost of trading event contracts includes more than the platform’s trading fee.
Say you take 100 contracts at 50¢ under the standard fee schedules:
Kalshi charges $1.75.
Polymarket charges $1.74.
OG.com charges $1.75 on most U.S. markets.
That difference is tiny, but the execution can matter more.
Suppose one platform has enough contracts available at 50¢, while another only has enough at 52¢. Paying an extra 2¢ across 100 contracts adds $2 to the position cost before you even compare fees.
The bid-ask spread can create a similar effect. If buyers are bidding 48¢ and sellers are asking 52¢, there’s a 4¢ gap. Buying at 52¢ and immediately selling at 48¢ would mean a $4 difference across 100 contracts before trading fees.
If there aren’t enough contracts available at the price you see, part of a larger order may fill at a less favorable price. That’s where slippage or price impact comes in.
Closing a position before settlement can add another trading cost because you’re making another transaction. Depending on the fee structure, the exit may generate another charge.
Funding can also change your total.
Kalshi charges no fee for ACH deposits or withdrawals and doesn’t add a fee to wire deposits, although your bank may. Debit-card deposits can cost up to 2%, while crypto transactions may involve third-party processor fees.
You can fund a Polymarket account by debit card, ACH, or wire, while cash withdrawals are currently listed as free.
For U.S. customers, where available, OG.com charges no platform fee for ACH or wire deposits, and some other supported funding methods also carry no OG.com fee. Your financial institution may still charge its own fee.
When you compare prediction market trading costs, it helps to use this formula:
That gives you a much better picture than the headline fee alone.
How to evaluate fee transparency across platforms
A fee schedule should let you quickly see what you pay when an order fills immediately, whether closing a position costs more, and whether some market categories use different pricing.
It’s worth checking the exceptions, too. With Kalshi, some markets use fees that differ from its standard schedule. Polymarket uses a separate fee formula for combo taker trades, while OG.com has different pricing for certain financial-market categories.
Rounding can affect small trades as well, so it helps to look at how the final fee is calculated rather than only the formula.
For U.S. traders, platform regulation and availability belong in the same check as fees.
Kalshi and QCX LLC, which operates Polymarket’s U.S. product, are listed by the Commodity Futures Trading Commission (CFTC) as designated contract markets (DCMs).
OG.com does business under the brand Crypto.com and provides access to event contracts offered by North American Derivatives Exchange, Inc. (NADEX), which is also listed by the CFTC as a DCM.
A DCM has to meet CFTC requirements on an ongoing basis. These include rule enforcement, protection of markets and market participants, financial integrity, recordkeeping, and system safeguards. Regulated prediction-market exchanges are subject to market-integrity rules designed to address conduct like manipulation and insider trading.
That doesn’t mean the CFTC guarantees a trade, market price, or outcome. It also doesn’t mean every contract is available to every U.S. resident. Availability can still depend on location, eligibility, and the particular market.
OG.com, for example, lists state-specific restrictions for some or all event contracts.
Prediction platform fees compared: Kalshi vs. Polymarket vs. OG.com
These three platforms use some of the same fee concepts, but the actual pricing can differ by order type and market.
Platform
Standard taker fee
Maker or resting order
Other fee details
Kalshi
General formula uses 0.07 × C × P × (1 − P)
No maker fee on many markets. Designated markets can use a maker-fee formula
Some markets and products use different schedules. ACH deposits and withdrawals have no Kalshi fee
Polymarket
Standard formula uses 0.0695 × C × P × (1 − P)
Standard makers currently receive a rebate
Traders with qualifying taker volume may receive rebates, and some trade types use different pricing
OG.com
Quick orders on most U.S. markets use the taker fee formula 0.07 × C × P × (1 − P)
Limit orders carry a 1.75% fee when the trade completes
Some U.S. financial-market categories use $0.02 per-contract pricing
Based on publicly available information as of September 29, 2026.
At 50¢, standard taker pricing is very close. For 100 contracts, Kalshi currently charges $1.75, Polymarket $1.74, and OG.com $1.75 on markets using its standard formula.
The bigger difference appears with maker orders. Polymarket currently pays a standard maker rebate. Kalshi may charge no maker fee or apply one depending on the market.
OG.com has a different order structure. A quick order executes immediately against available liquidity and cancels any portion that can’t fill right away. It uses the standard 0.07 × C × P × (1 − P) taker fee formula.
A limit order lets you set your price and can remain open until it fills or you cancel it. Filled limit orders carry a 1.75% fee.
OG.com also uses a different structure for some U.S. crypto, foreign exchange, commodities, and equity-index markets, charging a flat per-contract fee instead of the standard event-contract formula.
Fee schedules can change, so it’s worth checking the current platform documentation and the specific market before trading.
How to trade event contracts on OG.com
With OG.com, you can trade event contracts on real-world outcomes across different market categories.
Create an account: Open an account and complete sign-up, including identity verification. You can use our web or mobile platforms.
Browse markets: Explore markets across economics, culture, politics, sports, and other real-world events.
Review and trade: Compare the market price with your own view. Check the rules, fees, and settlement details before opening a position.
Monitor your position: After trading, your contract appears in your open positions, where you can track price movement as new information comes in.
Platforms may calculate fees from the contract price, number of contracts, order type, or market category. Some also treat maker and taker orders differently.
What is the difference between maker fees and taker fees on a prediction market?
A taker order fills immediately against an existing order. A maker order rests in the order book, and the platform may charge it differently or offer a rebate.
Do prediction market fees vary by event category?
Yes. Some platforms use different pricing for particular products or market categories. OG.com, for example, uses separate pricing for certain U.S. financial markets.
How do I calculate the total cost of a prediction market trade?
You can use this formula: Trading fees + spread + slippage + funding costs + exit costs − applicable rebates.
Important Information: Prediction is an event contract that is a derivatives product offered by North American Derivatives Exchange, Inc. (NADEX), a CFTC-regulated exchange, which does business under the brand OG.com Prediction Markets (OG) Crypto.com | Derivatives North America and uses a CFTC-regulated exchange that uses OG.com technology.
Trading on OG.com involves risk and may not be appropriate for all. By trading you risk losing your cost to enter any transaction, including fees. You should carefully consider whether trading on OG.com is appropriate for you in light of your investment experience and financial resources. Any trading decisions you make are solely your responsibility and at your own risk.
