Your Prediction Edge
Analysis12 min read

Prediction Market Fees Compared: The True Cost of Trading on Every Platform

Dave Haertel·

Fees are the silent killer of prediction market profits. A trade that looks like a 10% winner can turn into a 3% winner — or even a loss — after you account for all the costs. And the real cost of trading on each platform is very different from the headline fee rates.

This guide breaks down the complete cost structure of every major prediction market platform, including the hidden costs that most comparisons ignore. By the end, you'll know exactly what each trade costs on each platform and how to minimize the drag on your returns.

Fee Summary Table

| Fee Type | Kalshi | Polymarket | PredictIt | |----------|--------|------------|-----------| | Trading fee | 1-2¢/contract | None | None | | Profit fee | None | None | 10% of profit | | Withdrawal fee | None | Crypto off-ramp (0.5-1%) | 5% of balance | | Deposit fee | None (ACH), small (debit) | On-ramp varies (1-3%) | None | | Effective rate (winning trade) | 2-4% | 1-3% (with conversion) | 15-18% | | Effective rate (losing trade) | 0.5-1% | 0-1% | 0% |

The difference is dramatic. A trader making identical trades across all three platforms can lose 5-10x more to fees on PredictIt than on Kalshi. Let's break down exactly why.

Kalshi Fees: Simple and Transparent

Kalshi uses a straightforward per-contract fee model that's easy to understand and calculate.

Fee Schedule

Example: $500 Trade

You buy 1,000 Yes contracts at $0.50 ($500 invested).

If you win (event resolves Yes): | Item | Amount | |------|--------| | Payout (1,000 × $1.00) | $1,000.00 | | Cost of shares | -$500.00 | | Entry fee (1,000 × $0.01) | -$10.00 | | Exit fee (1,000 × $0.01) | -$10.00 | | Net profit | $480.00 | | Effective fee rate | 4.0% |

If you lose (event resolves No): | Item | Amount | |------|--------| | Payout | $0.00 | | Cost of shares | -$500.00 | | Entry fee (1,000 × $0.01) | -$10.00 | | Exit fee (no fee on loss) | $0.00 | | Net loss | -$510.00 | | Extra cost vs no fees | $10.00 (2%) |

Kalshi Fee Analysis

Strengths:

When fees matter most: Kalshi fees have the highest proportional impact on trades with:

Optimization tips:

Polymarket Fees: "Zero" With Asterisks

Polymarket's headline claim is zero trading fees, and on the platform itself, this is technically true. But the real cost of trading on Polymarket depends heavily on how you get money in and out.

Fee Schedule

The Hidden Costs: Getting Money In

Unless you already hold USDC on Polygon, you need to convert dollars to USDC and bridge it to Polymarket. Here's what that actually costs:

Method 1: Buy USDC on Coinbase, bridge to Polygon

Method 2: Use MoonPay or similar on-ramp directly in Polymarket

Method 3: Already hold USDC in a Polygon wallet

The Hidden Costs: Getting Money Out

After winning trades, you need to convert USDC back to dollars:

Step 1: Withdraw USDC from Polymarket to your wallet (free, minimal gas) Step 2: Bridge from Polygon to Ethereum mainnet (if needed): $1-10 Step 3: Send to exchange (Coinbase, Kraken, etc.): minimal Step 4: Sell USDC for USD: 0.5-1% Step 5: Withdraw to bank: free on most exchanges

Total off-ramp cost: approximately 0.5-2% depending on your method and amounts.

Example: $500 Trade (Starting From USD)

| Scenario | On-Ramp Cost | Trading Cost | Off-Ramp Cost | Total Cost | |----------|-------------|--------------|---------------|------------| | Buy via Coinbase + bridge | ~$7.50 (1.5%) | $0.00 | ~$5.00 (1%) | $12.50 (2.5%) | | Buy via MoonPay on-ramp | ~$17.50 (3.5%) | $0.00 | ~$5.00 (1%) | $22.50 (4.5%) | | Already hold USDC | $0.00 | $0.00 | ~$5.00 (1%) | $5.00 (1%) |

Polymarket Fee Analysis

Truly zero-cost for: Crypto-native traders who already hold USDC and plan to keep their funds in crypto. For this group, Polymarket is genuinely the cheapest platform.

Moderately cheap for: Traders who use efficient on/off-ramps (Coinbase Pro, direct USDC transfers). The 1.5-2.5% round-trip cost is comparable to Kalshi's fees.

Expensive for: Casual users who buy USDC via credit card on-ramps. At 4-5% round-trip, this actually exceeds Kalshi's simple per-contract fee for most trade sizes.

The bottom line: Polymarket's true cost depends entirely on your crypto setup. For traders already in the ecosystem, it's the cheapest option. For everyone else, do the math before assuming "zero fees" means "zero cost."

PredictIt Fees: The Fee Triple-Hit

PredictIt's fee structure is the most complex and the most expensive of any major prediction market. Understanding exactly how it works is critical before committing capital.

Fee Schedule

The Per-Market Problem

PredictIt's 10% profit fee is calculated on each market individually. This is much worse than a portfolio-level fee because you pay fees on winners but get no credit for losers.

Example portfolio:

Net portfolio profit: $40.00 Total fees paid: $15.00 (37.5% of actual profit!)

If this were calculated on portfolio P&L, you'd owe 10% of $40 = $4.00. Instead, PredictIt charges $15 — nearly 4x more.

The Withdrawal Tax

On top of profit fees, PredictIt charges 5% of every withdrawal. This applies to your entire balance, not just profits.

If you deposit $1,000, make $200 in net profits (after profit fees), and withdraw your $1,200 balance:

Your $200 in net profits just became $140. That's a 30% effective fee rate on your profits — before counting the profit fees you already paid.

Complete PredictIt Example: $500 Investment

You invest $500 in PredictIt, buy 500 Yes shares at $0.40 ($200), and the event resolves Yes.

| Item | Amount | |------|--------| | Payout (500 × $1.00) | $500.00 | | Cost of shares | -$200.00 | | Gross profit | $300.00 | | Profit fee (10% × $300) | -$30.00 | | Net account balance | $770.00 | | Withdrawal fee (5% × $770) | -$38.50 | | Take-home | $731.50 | | Actual profit | $231.50 | | Effective fee rate on profit | 22.8% |

The same trade on Kalshi (500 contracts at $0.40):

PredictIt costs 6.9x more in fees on the same winning trade.

Side-by-Side: Same Trade, Three Platforms

Let's make the comparison concrete with an identical $200 investment on the same market across all three platforms.

Setup: Buy Yes at $0.40, event resolves Yes. 500 contracts.

| Platform | Gross Profit | Total Fees | Net Profit | Fee Rate | |----------|-------------|------------|------------|----------| | Kalshi | $300.00 | $10.00 | $290.00 | 3.3% | | Polymarket (crypto-native) | $300.00 | ~$3.00 | ~$297.00 | ~1.0% | | Polymarket (USD round-trip) | $300.00 | ~$12.00 | ~$288.00 | ~4.0% | | PredictIt | $300.00 | $68.50 | $231.50 | 22.8% |

Over 100 trades in a year (assuming similar win rates and trade sizes), the difference between platforms amounts to thousands of dollars in fees.

Fees on Losing Trades

The cost of losing also varies significantly:

Setup: Buy Yes at $0.40, event resolves No. 500 contracts, $200 lost.

| Platform | Base Loss | Additional Fee Cost | Total Loss | |----------|-----------|-------------------|------------| | Kalshi | $200.00 | $5.00 (entry fee only) | $205.00 | | Polymarket | $200.00 | $0.00 | $200.00 | | PredictIt | $200.00 | $0.00 | $200.00 |

PredictIt and Polymarket charge nothing on losing trades. Kalshi's entry fee adds a small cost. However, this advantage is tiny compared to PredictIt's enormous costs on winning trades.

Fee Impact Over Time: A One-Year Model

Let's model a realistic active trader over one year:

Annual Results by Platform

| Metric | Kalshi | Polymarket (crypto) | PredictIt | |--------|--------|-------------------|-----------| | Gross profits (28 wins) | $8,400 | $8,400 | $8,400 | | Gross losses (22 losses) | -$5,500 | -$5,500 | -$5,500 | | Gross P&L | $2,900 | $2,900 | $2,900 | | Trading fees | -$500 | ~$0 | $0 | | Profit fees | $0 | $0 | -$840 | | Withdrawal fees | $0 | ~$80 | ~$250 | | On/off-ramp costs | $0 | ~$160 | $0 | | Net P&L after fees | $2,400 | ~$2,660 | ~$1,810 | | Fee drag | 17% | ~8% | ~38% |

PredictIt's fee structure takes 38% of gross profits — more than double Kalshi's drag and nearly 5x Polymarket's.

Tax Considerations

Prediction market profits are taxable income in the United States. Here's how tax treatment varies:

Kalshi: Issues 1099 forms to the IRS. Straightforward reporting. Gains and losses may qualify as Section 1256 contracts (60% long-term, 40% short-term) — consult a tax professional.

Polymarket: Does not issue US tax forms. You're responsible for tracking and reporting all transactions. Crypto transactions add complexity (cost basis tracking, on/off-ramp gains/losses).

PredictIt: Issues 1099-MISC for net winnings. Remember that PredictIt reports on a per-market basis, which may not match your actual portfolio P&L.

Tax complexity is an underappreciated cost. For traders making dozens of trades, Polymarket's lack of tax reporting creates meaningful bookkeeping overhead that has a real (if hard to quantify) cost.

Which Platform Has the Lowest Real Cost?

If you already hold crypto (USDC): Polymarket is the cheapest platform, hands down. Zero trading fees with minimal on/off-ramp costs makes it unbeatable for crypto-native traders.

If you trade in USD: Kalshi is the lowest-cost option. Simple per-contract fees with no profit tax, no withdrawal fee, and no conversion costs.

If you're fee-sensitive: Avoid PredictIt as a primary platform. Its fee structure is 4-7x more expensive than alternatives for the same trades.

The multi-platform advantage: Using multiple platforms isn't just about finding the best price — it's about minimizing total fee drag. Trade on the platform with the cheapest cost structure for each specific trade, and compare prices on Your Prediction Edge before every trade.

Minimizing Your Fee Drag

  1. Compare before every trade — check prices on all platforms via Your Prediction Edge to find the best combination of price and fees
  2. Sign up for free — our price alerts notify you when a better price appears on another platform
  3. Batch withdrawals — especially on PredictIt, withdraw infrequently to minimize the 5% fee hit
  4. Use efficient on-ramps — if using Polymarket, buy USDC through Coinbase Pro or similar low-fee exchanges
  5. Track everything — maintain a spreadsheet of trades, fees, and net returns to understand your true cost of trading

Fees compound relentlessly. A 1% improvement in fee efficiency on every trade adds up to thousands of dollars over a year of active trading. Understanding the true cost structure of each platform is one of the most impactful edges you can give yourself.

#fees#kalshi#polymarket#predictit#comparison#prediction markets
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