Kalshi vs Polymarket: Will CPI Core rise more than 0.0% in August

Last observed 2026-09-04 20:08 UTC. Prices and fees change constantly; the rules comparison is the durable part.

• SETTLEMENT_POLICY_MISMATCH — both venues publish settlement policy, but the published texts diverge
• THRESHOLD_OPERATOR_MISMATCH — one contract pays on 'above' and the other on 'at or below' the same number
• SETTLEMENT_GUARANTEE_UNKNOWN — the venue does not publish enough settlement policy to prove what happens in every branch (missing data, cancellation, revision)

The Polymarket leg here is the global venue, which US accounts cannot trade; it is shown for the rules comparison only.

Capital lock-up: about 13.7 days until the later of the two contracts settles.

Kalshi fine-print grade: F (35/100)
−20 FAMILY_POLICY_INCOMPLETE: the rules omit terms this contract family requires — the measurement basis, the revision rule, or the missing-release branch its peers publish
−20 MISSING_CANCELLATION_POLICY: the rules never say what happens to open positions if the event is canceled, voided, or never takes place
−15 MISSING_REVISION_POLICY: the rules never say whether a later revision of the underlying number changes the outcome
−10 MISSING_NEGATIVE_BRANCH: the rules say what settles the contract Yes but never state what settles it No

What Kalshi publishes

If the seasonally adjusted Consumer Price Index for All Urban Consumers: All Items less Food and Energy for August 2026, as published by the Bureau of Labor Statistics, increases by above 0.0%, then the market resolves to Yes. Please note that the value of the Underlying is the single-decimal value reported by the BLS. In the case of a delay in data caused by a federal government shutdown impacting the reliability of the Source Agency, the market’s latest Expiration Date will be extended to the sooner of the release of the Underlying or six months after the end of the government shutdown.

What Polymarket publishes

This is a market about the one-month percent change in the Consumer Price Index for All Urban Consumers excluding food and energy in August 2026 as reported by the Bureau of Labor Statistics. This market will resolve to the one-month percentage change in the Consumer Price Index for All Urban Consumers excluding food and energy (Core CPI-U) in August 2026 according to the monthly Bureau of Labor Statistics (BLS) report (seasonally adjusted change from the preceding month). The resolution source for this market will be the BLS Consumer Price Index report released for August 2026 (https://www.bls.gov/bls/news-release/cpi.htm), currently scheduled to be released on September 11, 2026, at 8:30 AM ET. Resolution of this market will take place upon release of the aforementioned data. Note: the resolution source for this market will be the official monthly BLS CPI news release, which reports core inflation (all items less food and energy) over 1-month periods to only one decimal point (e.g., 0.3%). Thus, this is the level of precision that will be used when resolving the market. For the avoidance of doubt, this market resolves on the core CPI figure — the all items index excluding food

Fees use each venue's published taker formula at the last observed price — see the fee calculator for any price.