Prediction Market Annualized Return Calculator

Free annualized return calculator for Kalshi and Polymarket: turn a contract price and resolution date into an annual yield, with fees and break-even chance.

Annualised return calculator

What does this contract earn per year?

Buying YES at 92¢ with 45 days to go pays 8.7% before fees if it resolves YES. This turns that into an annual rate so you can compare contracts with different deadlines.

Fee per contract (¢)

YES price 92¢Days until resolution 45

Return if YES+7.53%

Annualised (compounded)80.2%

Annualised (simple)61.1%

Break-even chance93.0%

If the contract resolves YES you earn 7.5% in 45 days. If it resolves NO you lose all of your $0.93 per contract. You break even only if YES happens at least 93.0% of the time. The annualised rate assumes you can reinvest at the same return again and again, which is rarely possible, so treat it as a way to compare contracts, not a forecast.

How to use the annualized return calculator

Set the YES price of the contract in cents.
Set the days until resolution.
Enter the fee per contract in cents. Use 0 if you want the figure before fees. The fee calculator shows what a trade costs at each platform.

You see:

Return if YES: the profit as a percentage of what you paid,
Annualised (compounded) and Annualised (simple): the same return stretched to a year,
Break-even chance: how often YES has to happen for the trade to be worth it.

The maths

Cost = price + fee, in dollars. A 92¢ price and a 1¢ fee give a cost of $0.93.
Return if YES = 1 ÷ cost − 1 (the contract pays $1).
Annualised (compounded) = (1 + return) ^ (365 ÷ days) − 1.
Annualised (simple) = return × 365 ÷ days.
Break-even chance = cost.

Worked examples

A likely event, 45 days away. YES costs 92¢ plus a 1¢ fee.

Cost: $0.93, so the return if YES is 1 ÷ 0.93 − 1 = +7.5%.
Annualised: 80% compounded or 61% simple.
Break-even chance: 93.0%. If YES really happens 93 times out of 100, you earn nothing on average.

A near-certainty, 10 days away. YES costs 97¢ plus a 1¢ fee.

Return if YES: +2.0%.
Annualised: about 109% compounded, 75% simple.
Break-even chance: 98.0%. One loss wipes out 49 wins.

Tips

Compare, don't forecast. Annualising puts contracts with different deadlines on one scale. It does not predict your return, because you must find a new trade every time and each one can lose.
Check the resolution rules. The risk in a high-probability contract is often in the wording, not the event. Read prediction market resolution.
Watch the fees and spread. On a 97¢ contract, a 1¢ fee takes half the return. See prediction market fees.
Mind liquidity. A wide spread or thin order book eats the yield. See prediction market liquidity.

To compare the price with your own estimate, use the edge calculator. To see what a price means as a probability or odds, use the price to odds converter. Profits are taxable, so read prediction market taxes.

Prediction Market Annualized Return Calculator FAQ

How do you calculate the annualized return on a prediction market contract?

Return if YES = 1 ÷ cost − 1, where cost is the price plus fees. Annualised (compounded) = (1 + return) ^ (365 ÷ days) − 1. Annualised (simple) = return × 365 ÷ days.

Why is the annualised return so high on short contracts?

Because a small return in a few days is multiplied up to a full year. A 2% return in 10 days becomes about 109% compounded, but only if you can find the same trade again and again, and every one wins.

Is buying a 95 cent YES contract a good deal?

It pays 5.3% if YES happens and loses 95 cents if it does not. It is a good deal only if the true chance of YES is above 95% after fees, and the market is saying exactly that.

What is the break-even chance?

The probability of YES at which the trade has zero expected profit. It equals the price plus the fee, so a 92 cent contract with a 1 cent fee breaks even at 93%.

Are high-probability contracts safe?

No. They pay small gains for a small chance of a large loss. Surprise results, rule disputes and early resolutions are the main risks.

Does money tied up in a contract matter?

Yes. That is what the annualised figure captures. A contract that resolves in a year at 95 cents earns about 5.3% a year, while one resolving in a month earns far more per year for the same return.