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Last Updated: August 20, 2026

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Overview

Kalshi APIs represent prices and contract quantities as fixed-point strings:
  1. Prices: fixed-point dollar strings (_dollars suffix), up to 4 decimal places
  2. Contract quantities: fixed-point strings (_fp suffix), up to 2 decimal places

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Prices

Prices are represented as fixed-point dollar strings.
  • *_dollars fields are fixed-point dollar strings with up to 4 decimal places (e.g., "0.1200")
  • Integer-cent fields cannot represent sub-cent prices; on markets with sub-cent ticks, read prices from the *_dollars fields
  • When combined with fractional contract sizes, intermediate calculations can reach up to 6 decimal places (for example, in fee rounding math)

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Price Level Structures

Each market’s valid prices form a fixed grid, described by two fields on Market responses:
  • price_ranges — an array of { start, end, step } bands in fixed-point dollars. This is the source of truth for valid prices: any price on the grid is valid, and any off-grid price is rejected. Consume it dynamically per market and snap order and quote prices to the relevant band’s step.
  • price_level_structure — a human-readable label for the grid. Do not key pricing logic off this name; new structures are introduced over time, and a client that reads price_ranges is automatically compatible with all of them.
Newer structures follow the naming convention center_{center}_edge_{edge}_cent, where the shorthands are whole = $0.01, half = $0.005, quint = $0.002, deci = $0.001, and centi = $0.0001. Tapered structures apply the finer edge tick near the boundaries of the price range — where small absolute price differences represent large relative changes in implied probability — and the center tick in between; most taper below $0.10 and above $0.90, while center_deci_edge_centi_cent tapers below $0.01 and above $0.99. When the center and edge ticks are equal, the grid is uniform. The older names (linear_cent, tapered_deci_cent, deci_cent) predate this convention. Whole-cent prices are valid in every structure. Structures are assigned per market — for example, multivariate (combo) markets use center_deci_edge_centi_cent. When a market’s structure changes, the price_level_structure_updated event on the market lifecycle WebSocket channels carries the new price_ranges.

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Fractional Contracts

Contract count fields use fixed-point strings and support fractional contract sizes.
  • *_fp fields are strings
  • Accept 0-2 decimal places on input (responses always emit 2 decimals)
  • Minimum granularity is 0.01 contracts
  • In requests where both integer and _fp fields are provided, they must match
Even if you are not placing fractional orders, you will encounter fractional values elsewhere in the API (for example, fills). If your system uses integer arithmetic, one approach is to internally multiply the _fp value by 100 and cast to an integer — treating "1.55" as 155 units of 1c contracts.

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Fee Rounding

Both sub-cent pricing and fractional contracts can produce balance changes with more precision than a user’s balance alignment. When this happens, the exchange applies a rounding fee to restore the applicable balance precision, and a fee accumulator issues rebates to prevent systematic overpayment. See Fee Rounding for the mechanics and worked examples.