What is tick size on Polymarket?
Filed 22 Jul 2026 · The Cent Signals desk
Every order book has to decide how finely it will let a price be stated, and that smallest allowed step is the tick size. On Polymarket, where a contract's price doubles as an implied probability, tick size is not just a display detail: it sets a limit on how precisely a probability can be expressed at all, which matters most at the extremes of a market. This guide covers what tick size means, what the platform's own public data shows about it, and why it matters more for some markets than others.
Tick size, defined
A contract on Polymarket is priced between zero and one dollar, and the tick size is the smallest amount that price is allowed to move. A one-cent tick means an order can rest at 1¢, 2¢, 3¢, and so on, but not at anything between two adjacent whole cents. A finer tick allows more gradation; a coarser one forces prices into wider steps. This is the same concept used across exchanges generally, applied here to a contract whose price is read directly as implied probability.
What the public data shows
A standard market's order-entry form on Polymarket generally presents prices in whole cents. Live data tells a slightly more detailed story at the edges. In the 2026-07-17 Cent Signals snapshot, several deep-tail and extreme-probability contracts show prices below a single cent stated to a hundredth of a cent, for example a French presidential candidate leg at 0.15¢ and a long-shot US presidential contender at 0.35¢. That level of granularity is finer than a whole-cent tick would allow, which indicates the underlying price precision available to these markets, particularly deep in a multi-outcome field, runs finer than the cent-denominated view most markets present.
Why tick size matters more at the extremes
A one-cent step is a modest move on a market trading near 50¢, roughly a two percent relative change. The same one-cent step on a market trading at 1¢ is a full doubling. Any market whose genuine implied probability sits well under one percent needs pricing finer than whole cents to be represented at all; otherwise the market is forced to round to the nearest tick, which can misstate a very small probability by a meaningful relative amount. This is most visible in the long tail of a wide multi-outcome field, where most legs are, by construction, priced well below one percent.
Tick size, spread, and negative risk sums
Tick size sets a floor on the narrowest achievable bid-ask spread: the tightest possible gap between the best resting bid and the best resting ask is one tick, no matter how much depth sits behind either side. It also plays a small role in why a negative risk field rarely sums to exactly one dollar even when complete: each leg can only land on an allowed price increment, and that rounding compounds with spreads and timing differences across a dozen or more legs into the small gaps that show up in practice.
Frequently asked questions
What is tick size on Polymarket?
Tick size is the smallest price increment an order book allows. On a market priced in cents on a one-dollar contract, a one-cent tick means an order can only sit at whole-cent prices, 1 through 99, with nothing in between. It sets a floor on how finely a price, and therefore an implied probability, can be expressed.
Can Polymarket prices display finer than one cent?
Yes, in practice. Deep-tail legs of multi-outcome fields and extreme-probability contracts commonly show prices to a hundredth of a cent, such as 0.15¢ or 0.35¢, in Polymarket's own public data. That reflects finer internal price precision than the whole-cent increments a standard order form typically presents for an ordinary market.
Why does tick size matter for a market priced near zero or one hundred cents?
A coarse tick becomes a large relative error at the extremes. A one-cent step is a small move on a market near 50¢ but is a full doubling on a market priced at 1¢. Long-tail legs in wide multi-outcome fields, where true probabilities can be a fraction of a percent, need finer-than-whole-cent pricing to be expressed at all, which is part of why sub-cent prices show up specifically in that part of the data.
Does tick size set a floor on the bid-ask spread?
Yes. The narrowest possible gap between the best resting bid and the best resting ask is one tick, so a market's minimum achievable spread is bounded by its tick size regardless of how much liquidity sits in the book. A finer tick allows a tighter minimum spread; a coarser one does not.
Does tick size affect whether a negative risk field sums exactly to a dollar?
It contributes to it. A field's YES prices are supposed to sum to roughly one dollar, but each leg can only sit at an allowed price increment, so rounding at the tick level is one of several small frictions, alongside spreads and timing, that keep the observed sum close to a dollar rather than landing on it exactly.
Related reading
This guide is editorial reference about publicly available Polymarket data. It is not financial advice, a tip, or a recommendation to take any position, and Cent Signals does not facilitate trades. For how the figures are collected, see the methodology page.