Kalshi Taker Fee Formula: How the $0.07 × p × (1-p) Parabolic Curve Really Works
A step-by-step mathematical breakdown of CFTC-regulated binary contract transaction costs and effective fee percentages across the 1¢ to 99¢ ladder.
- Peak absolute fee occurs at 50¢ ($0.0175/contract, or 3.50% friction on entry).
- Tail contracts (5¢ or 95¢) incur lower absolute fees ($0.0033/ct) but represent 6.6% percentage drag on invested capital.
- Resting limit orders (makers) incur zero taker fees, creating a 1.75¢/ct structural advantage over aggressive market orders.
- On a 51¢ contract, an uncalibrated trader winning 55% of trades makes +$2.25 net EV, with 43.8% of profit consumed by exchange fees.
Fee per contract = ceil( $0.07 × p × (1 - p) × 100 ) / 100 Where p = executable contract probability (0.01 to 0.99)
1. The Mathematical Structure of Kalshi Taker Fees
Under Kalshi's CFTC-filed Rulebook (Chapter 3), transaction friction is designed around maximum contract uncertainty. The quadratic term p × (1 - p) reaches its global maximum when p = 0.50 (0.50 × 0.50 = 0.25). Multiplying by the exchange multiplier $0.07 yields $0.0175 per contract.
Because fees are rounded up to the nearest cent on an aggregate order basis, purchasing 1 contract at 50¢ incurs a 2¢ minimum fee. However, purchasing institutional blocks (100 or 1,000 contracts) realizes the exact $0.0175 effective rate.
| Contract Price (p) | Absolute Fee ($/ct) | Capital at Risk | Percentage Fee Drag | Required Breakeven Win Rate |
|---|---|---|---|---|
| 0.05 ($5) | $0.0033 | $50.00 (1k cts) | 6.60% | 5.33% |
| 0.10 ($10) | $0.0063 | $100.00 (1k cts) | 6.30% | 10.63% |
| 0.20 ($20) | $0.0112 | $200.00 (1k cts) | 5.60% | 21.12% |
| 0.35 ($35) | $0.0159 | $350.00 (1k cts) | 4.54% | 36.59% |
| 0.50 ($50) | $0.0175 | $500.00 (1k cts) | 3.50% | 51.75% |
| 0.51 ($51) | $0.0175 | $510.00 (1k cts) | 3.43% | 52.75% |
| 0.70 ($70) | $0.0147 | $700.00 (1k cts) | 2.10% | 71.47% |
| 0.90 ($90) | $0.0063 | $900.00 (1k cts) | 0.70% | 90.63% |
| 0.95 ($95) | $0.0033 | $950.00 (1k cts) | 0.35% | 95.33% |
2. The Nominal vs Real Expected Value Trap
Competitor analytics terminals (such as Verso, Predly, and Stand.Trade) frequently display gross expected value calculations that ignore exchange fees. For example, if a trader enters a 51¢ YES position believing the true probability is 55%, competitor tools report a '+4.00% gross edge' and '+$40.00 gross EV per 1,000 contracts'.
In mathematical reality, the $17.50 taker fee must be deducted immediately from expected payoff. The real net EV is +$22.50 (+2.25¢/ct). Exchange taker fees consume 43.8% of the projected profit. If the trader's subjective assessment is overconfident by even 2.5%, the position has negative expectancy.
Frequently Asked Questions
Q1: Does Kalshi charge fees if my contract resolves to $0.00?
Kalshi charges taker fees upon order fill, not upon settlement. If your contract expires worthless, the taker fee paid on entry is not refunded.
Q2: How do maker orders avoid the Kalshi fee?
Resting limit orders that provide liquidity to the order book (makers) pay zero taker fees under Kalshi's schedule, and during incentive campaigns may qualify for maker volume rebates.
Q3: How does contract quantity affect the fee rounding?
Fees are computed across the total fill and rounded to the nearest cent. For single contracts, rounding up can result in a higher percentage fee, while for orders of 100+ contracts the fee converges to the continuous formula.
Related Guides & Teardowns
• Kalshi vs. Polymarket: Complete Real-World Fee, Gas, and Drag Comparison (2026) → • The Real Prediction Market Breakeven Formula: Why 50¢ Contracts Need a 52.75% Win Rate → • How Kalshi 15-Minute Bitcoin Contracts Settle: CME CF BRTI 60-Second TWAP Demystified →- Kalshi Rulebook Chapter 3: CFTC Regulated Exchange Fee Schedule (Official filing)
- QuanterraOS Canonical Backtest Corpus: 1,316 Settled KXBTC15M Windows (19,740 1-Minute Candles)
- Findings.md Section 9b: Empirical Decile Outcomes and Calibration Curve