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Last Updated: April 2, 2026

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Overview

Kalshi uses fixed-point representation across all APIs. This involves two independent changes:
  1. Subpenny Pricing — price fields use fixed-point dollar strings (_dollars suffix)
  2. Fractional Contracts — contract count fields use fixed-point strings (_fp suffix)
Two fields on Market responses indicate which of these features are active for a given market:
FieldTypeDescription
price_level_structurestringPrice level structure defining price ranges and tick sizes
fractional_trading_enabledbooleanWhether fractional order sizes are accepted

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Subpenny Pricing

Prices are represented as fixed-point dollar strings. 
{
    "price_dollars": "0.1200"
}
  • *_dollars fields are fixed-point dollar strings with up to 4 decimal places (e.g., "0.1200")
  • When combined with fractional contract sizes, intermediate calculations can reach up to 6 decimal places (for example, in fee rounding math)
Subpenny pricing is offered on a per-market basis. The price_level_structure field on Market responses indicates which pricing tier is active, and the price_ranges array provides the exact valid price intervals and tick sizes for that market.

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Price Level Structures

StructureRangesTick Size
linear_cent$0.00 – $1.00$0.01
tapered_deci_cent$0.00 – $0.10$0.001
$0.10 – $0.90$0.01
$0.90 – $1.00$0.001
deci_cent$0.00 – $1.00$0.001
tapered_deci_cent provides finer $0.001 (decicent) precision at the tails of the probability range — below $0.10 and above $0.90 — where small absolute price differences represent large relative changes in implied probability. The middle range uses standard $0.01 (cent) ticks. deci_cent applies $0.001 precision across the entire range.

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Fractional Contracts

Contract count fields use fixed-point strings. 
{
  "count_fp": "10.00"
}
  • *_fp fields are strings
  • Accept 0-2 decimal places on input (responses always emit 2 decimals)
  • In requests where both integer and _fp fields are provided, they must match
Check the fractional_trading_enabled field on Market responses to determine whether a given market supports fractional order sizes. Even if you are not placing fractional orders, you may encounter fractional values in other parts of the API (for example, fills on fractional-enabled markets). One way to prepare is to internally multiply the _fp value by 100 and cast to an integer. For example, treating "1.55" as 155 units of 1c contracts allows continued use of integer arithmetic.

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Fee Rounding

Both subpenny pricing and fractional contracts can produce sub-cent balance changes on fills. When this happens, the exchange applies a rounding fee to restore cent-alignment, and a fee accumulator issues rebates to prevent systematic overpayment. See Fee Rounding for the mechanics and worked examples.