How to Read Prediction Market Prices: A Beginner's Guide to Implied Probability

Prediction market prices look different from sports betting odds or stock prices, and that difference trips up a lot of new traders. The good news: the basic concept is simpler than almost any other financial instrument. Here is everything you need to understand before you place your first trade.

Cents Equal Probability

The core rule is straightforward: on platforms like Kalshi, each contract costs between 1 cent and 99 cents, and the price directly represents the market's implied probability that the YES outcome will occur.

A market trading at 62 cents means the collective view of all participants is approximately 62% probability that YES resolves true.

A market trading at 15 cents means approximately 15% probability.

When the event resolves:

• If YES: the contract pays out $1.00 (one dollar) per contract
• If NO: the contract pays out $0.00

So if you buy a YES contract at 62 cents and it resolves YES, you collect $1.00 and net $0.38 profit per contract. If it resolves NO, you lose your 62 cents.

This is a binary outcome — all or nothing — which is why these are often called binary event contracts.

How to Calculate Your Return

The math is simple once you understand the structure.

If you buy YES at 62 cents:

• Win scenario: collect $1.00, profit = $0.38 per contract (61% return on investment)
• Loss scenario: collect $0.00, loss = $0.62 per contract

If you buy NO at 38 cents (the other side of the same market):

• Win scenario: collect $1.00, profit = $0.62 per contract
• Loss scenario: collect $0.00, loss = $0.38 per contract

Notice that YES price + NO price should equal approximately $1.00 in a fair market. In practice, the sum is usually slightly more than $1.00 — the difference is the vig, which we will get to in a moment.

What Implied Probability Means

"Implied probability" is simply the market price expressed as a percentage. A 62-cent YES contract implies 62% probability. This is the market's collective estimate, aggregating the views of all buyers and sellers.

The important thing to understand is that implied probability is not always equal to the true probability of an event. That gap — between what the market thinks and what will actually happen — is where trading edge lives.

If a market is priced at 40 cents (40% implied probability) but your research suggests the true probability is 55%, you have found a mispriced market. Buying YES at 40 cents when you believe the fair value is 55 cents is positive expected value.

Finding these gaps is the entire game.

The Vig: What It Costs You to Trade

The vig (also called "juice" or "take") is the platform's compensation for providing the market. On an exchange like Kalshi, it manifests as a small spread between the best YES bid and the best NO bid.

In a perfectly fair market, YES price + NO price = exactly $1.00. In a real market:

• YES trading at 52 cents
• NO trading at 52 cents
• YES + NO = $1.04

That extra 4 cents is shared as the platform's vig. You "pay" it on entry because you are buying at the ask price rather than the theoretical mid-price. If you buy YES at 52 cents in a market where fair value is closer to 50 cents, you are starting the trade 2 cents behind fair value.

On liquid Kalshi markets, the vig is typically small — often 1-3 cents per dollar of exposure. On thin markets, it can be 10+ cents. Always check the spread before entering a position on a low-volume market.

Key Concepts to Know

Liquidity — How much money is in the market. High liquidity means tight spreads and easy entry/exit. Low liquidity means you pay more in spread and may struggle to exit a position before resolution.

Volume — How much has traded in a given period. High volume often signals that new information has hit the market or that significant participants are taking positions.

Price movement — When a prediction market price moves sharply, ask why. Did new information arrive? Is this a sentiment surge from media coverage? Understanding the cause of a price move is often more valuable than the price itself.

Resolution — Every prediction market has a defined resolution criteria. Read it carefully before you trade. "Will the Fed raise rates in March?" could resolve based on the target rate, the effective rate, or an announced change — the specific contract language matters.

A Practical Example

Suppose you see a Kalshi market: "Will the CPI print below 3% in February?" trading at 44 cents.

You look at recent inflation data, analyst forecasts, and the trend over the last six months. You conclude that the probability is closer to 55% — meaning you think the market is underpricing YES by about 11 cents.

You buy 100 YES contracts at 44 cents each, spending $44.

If you are right and CPI prints below 3%: you collect $100, for a $56 profit.

If you are wrong: you lose $44.

Your expected value calculation: (0.55 × $56) + (0.45 × -$44) = $30.80 - $19.80 = $11.00 positive expected value on the position.

That is how every prediction market trade should be evaluated — not "do I think this will happen?" but "is the market pricing this correctly, and what is my edge?"

The probability converter tool on this site automates these calculations so you can run the math quickly on any market.