Kalshi vs Polymarket Prices: Why the Same Event Differs

Why can the same event have two prices?

A price is what traders on one platform will pay for one written outcome; our prediction markets vs. sports betting guide explains the mechanics. Change the platform and almost every part of that sentence can change.

What differs	What to compare	How it opens a gap
Settlement source	The data provider or report named in the rule	Two sources can publish different final numbers for the same day
Outcome wording	Thresholds, ranges, "or above" and "or below"	A reading on a boundary can land in different outcomes
Outcome list	How many names or ranges are offered	A name missing from one list cannot be priced there
Clock	When trading closes and when each price was captured	Prices taken minutes apart are not the same snapshot
Traders and depth	How much is resting at the quoted price	In a quiet market the last trade can be stale
Which platform	Polymarket US or the international Polymarket	They are separate platforms with separate markets

A New York example: one day's high, two rulebooks

The daily high in New York City looks like a question with one answer. On paper the two listings even match: both platforms cut the day into two-degree ranges with an open-ended outcome at the top and the bottom.

The difference is in the last line of the rule. Kalshi's contract says the official value is the maximum temperature as reported by The Weather Company, and its rule adds a warning: "Preliminary Weather Company data may be subject to rounding and conversion differences from the final reported value." Polymarket US's contract says the outcome is verified from the National Weather Service's climatological report for Central Park.

The two sources will often agree, but nothing in either rule says they must. When the day's high sits right on the edge of a range, a one-degree difference decides which outcome resolves Yes on each platform. Traders who know that can reasonably price the boundary outcomes differently, and neither price is wrong.

Neither rule settles on a forecast. The National Weather Service publishes forecasts and warnings you can read alongside a contract, but the forecast is an input to your view, not the settlement value. Our guide to Kalshi weather markets in New York covers how temperature contracts are built.

How do you read a gap? A made-up example

Suppose Platform A shows an outcome at 40 cents and Platform B shows what looks like the same outcome at 30 cents. That is a 10-point gap. Three questions come before any conclusion:

1. Is it the same outcome? Read both rules. If the sources or the range boundaries differ, the two contracts can settle differently on the same day.
2. Is it the same moment? Check when each price was last traded. A 40-cent price from an hour ago and a 30-cent price from a minute ago describe two different states of the world.
3. Could you actually trade at those prices? A displayed price may be the last trade, not an offer you can take. Fees and the spread between buyers and sellers eat into a small gap quickly.

A gap is not free money. Buying Yes on one platform and No on the other only cancels out if both contracts settle on the same fact, and the example above shows why they might not.

Why do awards markets diverge so much?

Before nominations are announced, the list of names in an awards market is the platform's own guess at the field. One platform may list dozens of possible winners and another only a handful. A name that is missing from one list cannot attract trades there, so the prices on the shorter list are spread across fewer outcomes and cannot be laid side by side with the longer one.

The rules are usually close. Kalshi's Oscar contracts resolve Yes if the named person "has won" the category at the 99th Academy Awards, and Polymarket US's Grammy contracts settle on who wins at the 69th Annual Grammy Awards, with the Recording Academy as the source. The gap comes from the lists and the traders, not from the definition of a win.

Nominations day is when the lists converge, because every platform then knows the real field. The Academy's show-date announcement and the Recording Academy's 2027 Grammys announcement give the official dates.

Which "Polymarket" is in the chart?

Polymarket US is a separate platform from the international Polymarket, with its own markets, rules and traders. A price tracker or a social media chart labeled only "Polymarket" may be showing the international platform, not the app New Yorkers use. If a chart shows a market that the app does not list, that is the likely reason.

For how the two platforms open to New Yorkers compare on devices, offers and markets, see our Kalshi vs. Polymarket guide for New Yorkers.

What should you check before comparing two prices?

1. The source. Find the data provider or publication named in each rule.
2. The boundaries. Line up the ranges or thresholds and look at what happens to a reading on the edge.
3. The list. Count the outcomes and note any name that appears on only one platform.
4. The clock. Note when each market closes and when each price last traded.
5. The platform. Confirm whether a "Polymarket" figure comes from Polymarket US.

Where can New Yorkers compare these markets?

Check Kalshi first, then Polymarket US, then OG; listings differ on each, and our platform reviews describe what each one covers. Their New York status is the same: Available — dispute pending (as of October 13, 2026). Our New York legality guide, Kalshi in New York page and Polymarket in New York page follow the dispute.

Kalshi's, Polymarket US's and OG's minimum age is 18; we recommend 21+.

Frequently asked questions

Why do Kalshi and Polymarket show different prices for the same event?

Each platform writes its own contract. The settlement source, the outcome boundaries, the list of outcomes, the closing time and the traders can all differ, so two prices that look comparable may be answering slightly different questions.

Does a price gap mean one platform is wrong?

No. A gap records two prices, not an error. If the two contracts settle on different sources or use different outcome lists, both prices can be reasonable at once.

Is a gap between two platforms free money?

No. Opposite positions on two platforms only offset each other if both contracts settle on the same fact. Different sources, fees and stale prices can turn an apparent gap into a loss on both sides.

Do Kalshi and Polymarket US settle New York temperature markets the same way?

Not necessarily. Each rule names its own data source for the day's high, and the two can differ. The sources we read are listed in the status box at the top; always read the rule on the contract you are trading.

Is Polymarket US the same as Polymarket?

No. Polymarket US is a separate platform from the international Polymarket, with its own markets and rules. A chart labeled only "Polymarket" may not show the US app's prices.

Can New Yorkers use both Kalshi and Polymarket US to compare prices?

Both are open to New Yorkers while a legal dispute is pending. The current status line is in the last section above, and our Kalshi in New York page tracks any change.