What is a prediction market profit calculator?
It's a quick way to translate a contract price and a dollar amount into the numbers you actually need to make a decision: how many contracts you'll own, what they pay if you win, your profit, your loss and your break-even probability.
How prediction market payouts work
On regulated US exchanges like Kalshi, every Yes/No contract settles to either $1 (if the event happens) or $0 (if it doesn't). You pay the current price — say 35¢ — to buy a Yes contract. If Yes resolves, you receive $1 per contract. If No resolves, you receive nothing.
Your profit per contract is therefore $1 − price if you win, and −price if you lose. The calculator multiplies by the number of contracts your investment buys.
How event contracts are priced
Contract prices float between 1¢ and 99¢ and represent the market's collective belief in the probability of the underlying event. A 60¢ contract implies the market thinks Yes has a 60% chance of resolving true.
How to calculate expected value
Turn on advanced mode and enter your own probability. Expected value = (your probability × profit if win) − ((1 − your probability) × amount invested). A positive number means the trade has positive EV at your estimate.
Example trades
- Buy 100 contracts of Yes at 30¢ for $30. If Yes resolves, you receive $100 — a $70 profit (233% ROI).
- Buy 100 contracts of No at 70¢ for $70. If No resolves, you receive $100 — a $30 profit (43% ROI).
- Sell out before settlement at 45¢ after buying at 30¢ for a +50% return without waiting for resolution.
Common mistakes
- Treating large gross payouts as more important than ROI on the capital risked.
- Forgetting that maximum loss equals the full amount invested, every time.
- Ignoring fees, which scale with contract count.
- Sizing positions without an explicit probability view.
Questions
Frequently asked questions
How is profit calculated on a prediction market?+
Profit equals payout ($1 per contract if your side wins, $0 if it loses) minus the amount you paid. The calculator scales this for any investment amount.
What is break-even probability?+
It's the win probability you'd need for the trade to be a fair bet. For a Yes contract bought at 40¢, you'd need at least a 40% true probability of Yes to break even on expectation.
Are prediction market profits taxable?+
In the US, profits from regulated event contracts are generally taxable. See an accountant familiar with your situation.
What's the maximum I can lose?+
The full amount you invested. Contracts settle at $0 or $1 — there's no margin call or additional liability.
Does this calculator include fees?+
No — it shows gross profit. Fees vary by platform and trade type. Subtract roughly 1–2% per trade to be conservative.