Polymarket Tick Size (2026): Minimum Ticks, Changes and the API

What tick sizes does Polymarket use?

An order price must be a whole multiple of the market's active increment. Polymarket's documentation notes that the 0.0025 increment applies only to World Cup to-advance, moneyline, spread and total markets, and tells integrators to read the active value from the market rather than assume one.

How do you get a market's tick size from the API?

There are three places to read it, and they agree:

This reads both the Gamma value and the CLOB value for a market, with Node 18 or newer and no keys:

const slug = 'your-market-slug';

const [market] = await (await fetch(`https://gamma-api.polymarket.com/markets?slug=${slug}`)).json();
const [yesToken] = JSON.parse(market.clobTokenIds);

const { minimum_tick_size: tick } = await (await fetch(`https://clob.polymarket.com/tick-size?token_id=${yesToken}`)).json();
console.log({ gammaTick: market.orderPriceMinTickSize, clobTick: tick, minOrderSize: market.orderMinSize });

Why does Polymarket's tick size change?

Because the right increment depends on where a market trades. A market sitting at 99 cents has little room left on a one-cent grid, so a finer tick lets traders quote between 99 and 100 cents. Polymarket can change a market's tick size while it is live. When it does, every resting order and every price you compute has to follow the new grid.

Short crypto markets show both settings. In our checks, a 5-minute Bitcoin market trading near even odds quoted in one-cent steps, while Bitcoin markets trading near the extremes quoted in tenths of a cent.

How do you catch tick size changes?

Subscribe to the market channel of Polymarket's WebSocket. When a market's increment changes, it sends a tick_size_change event with the old and new values:

{
  "topic": "market",
  "type": "tick_size_change",
  "payload": {
    "market": "0x747dc809fb79e1b05be09c42d6179459a58de2ef3e40f02484a4e1260f741f75",
    "tokenId": "107505882767731489358349912513945399560393482969656700824895970500493757150417",
    "oldTickSize": "0.01",
    "newTickSize": "0.001",
    "timestamp": "1782753357257"
  }
}

Update your cached tick for that token as soon as the event arrives, then re-price anything you were about to send. Streaming setup is covered in the Polymarket WebSocket API guide.

Why was my Polymarket order rejected for tick size?

Before matching, the CLOB checks that an order's price meets the market's minimum tick size, and rejects it if not. The error looks like this:

order 0xabc... is invalid. Price (100) breaks minimum tick size rule: 0.1

Rounding onto the grid fixes it. Round a buy down and a sell up, so the rounded price never pays more or accepts less than you intended:

function toTick(price, tick, side) {
  const steps = side === 'buy' ? Math.floor(price / tick + 1e-9) : Math.ceil(price / tick - 1e-9);
  const decimals = String(tick).split('.')[1]?.length ?? 0;
  return Number((steps * tick).toFixed(decimals));
}

toTick(0.5372, 0.01, 'buy');   // 0.53
toTick(0.5372, 0.001, 'sell'); // 0.538

How do you handle tick sizes across venues?

Every venue has its own price grid, and Kalshi, Polymarket and Polymarket US do not share one. The Predictefy API reads each Polymarket token's current tick size from the CLOB when it builds an order, along with its fee details and negative risk flag, and stores the increments Polymarket US publishes for each market in its catalog. That way one integration handles each venue's grid across 15+ venues.

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