Methodology

Every number on GeoOdds is a market price, not an editorial opinion. This page explains exactly where the data comes from and how we present it.

Where the data comes from

Probabilities are sourced from two regulated-or-public prediction markets via their free, public APIs:

• Polymarket — current prices, market metadata and volumes from the public Gamma API; full price history from the public CLOB API. Polymarket is the primary source for every page on this site.
• Kalshi — prices from Kalshi’s public trading API, used only in the side-by-side comparison module.

We do not adjust, model or re-weight any price. What traders pay is what you see.

What “implied probability” means

A prediction-market contract pays $1 if the event happens and $0 if it doesn’t. If that contract trades at 65¢, the market is collectively pricing a 65% chance the event occurs — that price is the implied probability. Because traders profit by correcting mispriced contracts, these numbers tend to absorb new information faster than polls or pundits. We also display each headline price as American (+154 / -186) and decimal (1.54) odds for bettors used to those formats.

Refresh cadence

Every data page revalidates against the live APIs every 10 minutes. The “24h change” figures are computed by diffing each market’s hourly price history over the trailing day — not from a vendor field — so movers reflect genuine traded prices.

How Polymarket–Kalshi matching works

The two venues word their markets differently, so cross-market comparisons are dangerous if done sloppily. Our nightly matcher pairs markets only when titles, resolution dates and resolution criteria align with at least 85% confidence, or when a human has manually pinned the pair. Anything below that threshold is simply not shown — you will never see a Kalshi comparison on a page unless the markets are verified equivalents.

What this site is not

GeoOdds is a data aggregator. We are not affiliated with Polymarket or Kalshi, we do not take positions in any market, and nothing here is investment advice. Market prices can be wrong — especially in thin markets — and past probability moves do not predict future ones.

Learn more

New to prediction markets? Our partner site has plain-English guides on how they work, how odds formats convert, and how to read a probability chart: predictor.tips — how prediction markets work.