What is BRTI? The CF Benchmarks Bitcoin Real Time Index explained

If you read the rules of a Kalshi Bitcoin market, you will see "BRTI". This TickTilt guide explains what it is without the math jargon.

The basic idea

BRTI stands for the CME CF Bitcoin Real Time Index, run by CF Benchmarks. It is a live U.S. dollar price for one bitcoin, published continuously throughout the day. CF Benchmarks describes it as the price input for settling event contracts and prediction markets offered by Kalshi, CME Group and ForecastEX.

Where the number comes from

Instead of copying the last trade from one exchange, BRTI looks at the order books of a set of approved "constituent" exchanges. An order book is the list of open offers to buy (bids) and sell (asks) at different prices. In simplified steps, the methodology:

1. Pulls the current order books from each constituent exchange.
2. Combines them into one big consolidated order book, capping very large orders so a single giant order can't dominate.
3. Works out a "mid price" (halfway between buying and selling prices) at different trade sizes.
4. Uses depth only up to the point where the spread stays tight (within 0.5%), and weights the prices closest to the top of the book most heavily.

The result is meant to be a fair estimate of the instantaneous price you could actually trade at, across several venues.

Why use an index at all?

Any one exchange can have a brief glitch, a thin moment, or a price slightly out of line with everyone else. Blending several order books makes the number harder to push around and less dependent on any single venue. Kalshi's help center gives this as its reason for using CF Benchmarks indexes.

BRTI vs. the price on your app

Because BRTI blends several exchanges, it will usually be very close to, but not exactly equal to, the price you see on Coinbase or a chart site. Most of the time the gap is tiny. In a 15-minute round decided by a few dollars, that tiny gap can matter. TickTilt shows a live Coinbase price as a stand-in, which is why we say close rounds can settle the other way.

How Kalshi uses it

For the 15-minute rounds, Kalshi does not use a single BRTI value. It averages 60 values from the final minute and compares that to the same kind of average from just before the round opened. See our guide on how 15-minute rounds settle.

Other coins

CF Benchmarks runs similar real-time indexes for other cryptocurrencies, such as Ether. Each Kalshi market's rules name the exact index it settles on.

Sources

CF Benchmarks: BRTI · CME CF Real Time Indices methodology (PDF) · Kalshi Help Center