Expected value and edge
Expected value is the single most useful idea for thinking clearly about whether a trade is good. It turns gut feel into a number you can actually evaluate.
Here is how it works on Kalshi. This is educational, not financial advice.
What expected value is
Expected value (EV) is the probability-weighted average of what a trade pays. On Kalshi, if you buy a contract at a price and you believe the true probability of winning is higher than that price implies, the trade has positive expected value. In simple terms, EV compares what you pay against what the outcome is really worth.
Edge is the gap
Your edge is the difference between your probability estimate and the market's price. Buy a 30 cent contract you genuinely believe is worth 45 cents and you have a 15 cent edge per contract. No edge means no reason to expect profit, because the price already reflects the consensus view.
Fees eat into edge
Edge is measured after costs, not before. A few cents of taker fee can turn a thin positive-EV trade into a losing one, especially if you round-trip in and out. Always subtract realistic fees before deciding whether an edge is real.
Positive EV still loses sometimes
This is the part people forget: positive expected value is a long-run statement, not a promise about the next trade. Even a great edge loses plenty of individual bets along the way. The point of EV is to make many positive-EV decisions and let the math play out over time, which is also why position sizing matters so much.