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The CFTC advises prediction-market customers to trade only with risk capital after living expenses and other savings needs, understand fees and contract rules, and be cautious of pressure to risk more. Kalshi's Member Agreement says event-contract trading can involve substantial loss and is highly speculative.
This guide turns those risk statements into a transparent worksheet. It does not choose an appropriate loss budget for a particular person, because income stability, savings, obligations, experience, time horizon, and tolerance for loss differ.
The formulas below apply to a cash-funded purchase of a standard event contract. They do not apply to Kalshi perpetual futures. Perpetual futures introduce margin, leverage, funding payments, liquidation, and a separate margin account. A leveraged position can change risk much faster than a fully paid event-contract purchase.
Complex event contracts can also have partial or multi-outcome payouts. Read the market rules and replace the simple $1-or-$0 assumption whenever the contract specifies something different.
Call the maximum loss allocated to this independent thesis L. It must be a dollar amount, not a feeling such as “high conviction.” The CFTC's risk-capital principle supplies the outside boundary: money needed for living expenses or savings is not the input.
This guide deliberately gives no universal percentage. A fixed percentage can be too large for someone with concentrated exposures or too small to be meaningful for a different situation. The decision belongs to the trader, and choosing it may require qualified financial advice.
For a standard cash-funded event contract purchased at executable price p, with n contracts and estimated total fees f:
The second formula is only a first pass because fees can depend on price and quantity. Calculate a candidate n, obtain the order panel or fee-model estimate for that quantity, then reduce n until n × p + f ≤ L.
In software, represent money as fixed-point decimal values or integer units rather than binary floating-point numbers. Otherwise a value mathematically equal to 115 can be stored just below 115 and incorrectly floored to 114.
Suppose a hypothetical worksheet uses a self-chosen loss budget of $50, an executable purchase price of $0.42, and an estimated total fee of $1.70 for the candidate order:
floor(($50.00 - $1.70) ÷ $0.42) = 115 contracts.115 × $0.42 = $48.30.$48.30 + $1.70 = $50.00.115 × $1 = $115.00.$115.00 - $50.00 = $65.00.If the current fee estimate or weighted-average fill is higher, 115 no longer fits. Recalculate rather than rounding the risk down in your head. The Kalshi payout calculator can save and share the price, quantity, fee, and probability inputs.
The best displayed ask may not cover the full quantity. Kalshi's Quick Orders documentation shows that a larger order can span multiple price levels. The order book also shows how much quantity rests at each price.
Before accepting a contract ceiling:
The CFTC explains that customers can trade out before settlement at the current market price. That is a capability, not a liquidity guarantee. A thin market can have a wide spread, insufficient bid depth, or no acceptable exit when needed.
Market tickers are not independent risk buckets. Several positions can depend on the same underlying release, election result, court decision, weather system, or macro scenario.
If three positions each fit a $50 per-trade ceiling but all lose under the same CPI surprise, the relevant stressed exposure can be $150 plus any extra execution cost. Compare that total with the theme-level risk budget before placing the third trade.
Correlation can also be hidden. A Fed decision contract, a rate-path contract, and an equity-index event contract may be driven by the same economic data even though the tickers and settlement dates differ.
A positive expected-value estimate does not prove a position is safe. For a standard $1 event contract, a simplified estimate is:
Here q is the trader's estimated probability of the purchased side paying $1. The price and fee can be observed or estimated from the order; q is uncertain. Run sensitivity cases rather than treating a point estimate as truth.
| Input risk | Stress question | Possible response |
|---|---|---|
| Probability error | What if q is 5 or 10 points lower? | Recompute EV and avoid sizing from the optimistic estimate alone. |
| Fee error | What if the market or order has a higher fee? | Use the current fee schedule and order estimate; reduce quantity. |
| Slippage | What if the order walks several levels? | Use weighted-average price or a limit order with fill risk. |
| Correlation | Which other positions lose in the same scenario? | Aggregate them under one theme budget. |
| Exit failure | What if no acceptable bid exists? | Evaluate the hold-to-settlement loss. |
| Rule error | Could the settlement source differ from the headline intuition? | Read the official market rules before sizing. |
The Kelly criterion can translate a probability edge and payoff into a growth-optimal fraction under specific assumptions. The calculation is not a safety guarantee and is extremely sensitive to the estimated probability.
Common failure points include:
A mathematical fraction can be a scenario input, but it should not override the dollar loss budget, correlated-exposure cap, or product-specific risk disclosure.
n × p + f ≤ L.There is no source-backed universal percentage. Choose a dollar loss budget from risk capital after living expenses and savings needs, then calculate a contract ceiling and stress correlated positions, fees, slippage, and the possibility that no exit is available.
For a standard purchased event contract held through an incorrect outcome, a conservative cash-at-risk estimate is contracts times executable purchase price plus estimated fees. Confirm product terms because complex event contracts and perpetual futures have different payout and risk mechanics.
No. Positions driven by the same event or data release can fail together. Add their stressed losses into one theme-level exposure before comparing the total with the chosen loss budget.
No. The CFTC notes that customers may trade out at the current market price, but that does not guarantee a liquid bid, a favorable price, or a full fill. Size a position so the hold-to-settlement loss scenario remains tolerable.
Kelly sizing is highly sensitive to the probability and payoff inputs. A model output is not a safety guarantee. If the probability estimate is poorly calibrated or the payoff omits fees, slippage, partial outcomes, or correlation, the suggested fraction can be misleading.
No. This worksheet is for cash-funded event-contract purchases. Kalshi perpetual futures use margin, leverage, funding, liquidation, and a separate risk framework. Review the official perpetual-futures risk disclosures instead.
Educational information only, not individualized financial advice. Trading can cause substantial loss. Product terms, fees, liquidity, and risk controls can change. Read current official rules and disclosures and consider qualified advice for your circumstances. Kalshi View is independent and is not affiliated with Kalshi Inc.