Polymarket Price to Beat API (2026): How to Get the Start Price

What is the price to beat on Polymarket?

It is the starting price a crypto Up or Down market measures against. Polymarket's rules for the 5-minute, 15-minute and 4-hour markets say the market resolves Up if the time-weighted average price of Bitcoin, generated by Chainlink, over the time range is greater than or equal to the price at the beginning of that range. The resolution source is Chainlink's BTC/USD TWAP data stream, not any exchange's spot price.

The same pattern covers other coins, with the ticker swapped in, such as sol-updown-5m- and xrp-updown-5m-. How the short markets work day to day is covered in how to track 5 minute Bitcoin markets.

How do you get the price to beat from the API?

Ask the Gamma API for the event by slug. No key is needed. A settled window returns both values:

curl -s "https://gamma-api.polymarket.com/events?slug=btc-updown-5m-1790965500"

"eventMetadata": {
  "finalPrice": 84595.45276441918,
  "priceToBeat": 84556.29882459581
}

This pulls the last ten settled 5-minute windows and the result each one produced, which is the raw material for a backtest:

const WINDOW = 300;
const now = Math.floor(Date.now() / 1000);
const latest = now - (now % WINDOW) - 3 * WINDOW;

for (let start = latest - 9 * WINDOW; start <= latest; start += WINDOW) {
  const [event] = await (await fetch(`https://gamma-api.polymarket.com/events?slug=btc-updown-5m-${start}`)).json();
  const { priceToBeat, finalPrice } = event?.eventMetadata ?? {};
  if (finalPrice == null) continue;
  const result = finalPrice >= priceToBeat ? 'Up' : 'Down';
  console.log(new Date(start * 1000).toISOString(), priceToBeat.toFixed(2), finalPrice.toFixed(2), result);
}

When does the price to beat appear?

Later than most traders expect. In our checks on 2 October 2026, a 5-minute window had no eventMetadata at all while it was trading. The previous window's finalPrice appeared about five and a half minutes after that window closed, and the next window's price to beat had still not appeared seven minutes after it opened.

Gamma is a reliable record once the metadata lands. Across 22 consecutive 5-minute windows, every price to beat equaled the previous window's final price, and every market resolved Up exactly when its final price was at or above its price to beat. For backtests and settlement checks, Gamma is the source. For a live window, it is too slow.

How do you track the price to beat live?

Read the Chainlink TWAP stream yourself, and take its value at the window boundary as the start price. Polymarket streams reference prices through PolyBolt, its real-time data service, which replaces the older RTDS feeds:

• prices.crypto.twap streams Chainlink-computed crypto TWAPs with a fixed 60-second window, the same kind of stream that settles these markets, with symbols such as btcusd.
• prices.crypto streams crypto reference prices in US dollars.

Both need an authenticated secure client from @polymarket/client 0.11.0 or later. Each new subscription starts with a snapshot of the previous two minutes, so a bot that connects just after a boundary still sees the value it needs.

To see the market and the reference prices together, the Predictefy API streams Polymarket's Up and Down order books over one WebSocket alongside Binance's BTC/USDT price and Chainlink's on-chain BTC/USD price. That is a close reference rather than the TWAP stream that settles the market. We used exactly that setup to run our Claude vs GPT-6 trading test on these markets.

How do hourly Bitcoin Up or Down markets work?

They use a different source. Polymarket's hourly Bitcoin Up or Down markets resolve Up if the close of the Binance BTC/USDT 1-hour candle that begins at the stated time is greater than or equal to its open. The price to beat is that candle's open price, which Binance's public kline data provides, and those events carry no priceToBeat in Gamma.

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