Enter your investment and the share price to instantly see how many shares you get, what you collect if you win, your exact ROI, and — most importantly — the breakeven win rate you need to be profitable long-term.
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Also see the true cost of each trade: Polymarket Fee Calculator →
On Polymarket, every outcome is represented as a share that costs between 1¢ and 99¢ and pays out exactly $1.00 if it resolves YES. That price is not arbitrary — it is the market's collective estimate of the probability that the event occurs. A share trading at 40¢ implies a 40% chance of YES. At 72¢, the crowd thinks there is a 72% chance. This is the core mechanic that makes prediction markets unique: price and probability are the same number.
The breakeven win rate is the single most important number on this page. It tells you how often you need to win bets at this price to break even over many trades. At 40¢, you need to be right at least 40% of the time to not lose money in the long run. At 10¢, you need to win at least 10% of the time. The rule is simple: your win rate must equal or exceed the share price expressed as a percentage. Any win rate above that and you are profitable; any win rate below and you are bleeding money slowly.
A 5¢ share looks cheap — you can buy 2,000 of them for $100, and if it hits you collect $2,000. But the market is pricing that share at 5¢ because it believes the event has only a 5% chance of happening. To make money consistently on 5¢ longshots, you need to find situations where your true belief in the probability is meaningfully above 5%. If you are just guessing, the house (the crowd) wins in the long run. Cheap shares are not value plays — they are only value plays if you have a genuine informational edge that justifies a higher probability than the price implies.
Payout and profit are easy to confuse. Payout is the total cash you receive from Polymarket when the market resolves YES — it includes the return of your original investment plus the winnings. Profit is only the gain: payout minus what you put in. If you invest $100 at 40¢ and win, you receive $250 in payout, but your profit is only $150. The ROI figure uses profit, not payout, against your initial investment, which is why a 40¢ position winning pays out 150% ROI rather than 250%.
The gap between what you believe is the true probability of an event and what the market prices it at is your edge. If a share is trading at 30¢ (30% implied probability) but you genuinely believe the true probability is 50%, you have a significant positive edge and the bet is worth taking. If you have no reason to believe your estimate is more accurate than the market's, you have no edge — and over time, transaction costs and variance will eat your capital. The calculator above shows you the implied probability and the breakeven threshold so you can make an honest assessment before committing capital.
Expected value (EV) is what you expect to earn or lose per bet on average over many repetitions. At 40¢ with $100 invested, if your true win probability is exactly 40%, your EV is exactly zero. If your true win probability is 55%, your EV per bet is positive and the series is profitable. The "number of similar bets" input above aggregates this to help you think about a strategy, not just a single trade — because any single trade can go either way even with a strong edge.
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