Last Updated: March 3, 2026
Overview
Kalshi is migrating from integer to fixed-point representation across all APIs. This involves two independent changes:
- Subpenny Pricing — price fields transition from integer cents to fixed-point dollar strings (
_dollars suffix)
- Fractional Contracts — contract count fields transition from integers to fixed-point strings (
_fp suffix)
Two fields on Market responses indicate which of these features are active for a given market:
| Field | Type | Description |
|---|
price_level_structure | string | Price level structure defining price ranges and tick sizes |
fractional_trading_enabled | boolean | Whether fractional order sizes are accepted |
Deprecation Timeline
_fp and _dollars fields returned and accepted across REST and WebSocket APIs — Completed January 29, 2026- Legacy integer count fields and integer cents price fields will no longer be returned. Fractional order sizes enabled per-market. Users must migrate to
_fp and _dollars equivalents — March 12, 2026 (they may be truncated prior to March 12 and will be removed after March 12)
- REST endpoints will no longer accept integer fields for contract counts — TBD
Please follow along the changelog for further updates.
Subpenny Pricing
Prices are represented in two formats: integer cents (legacy) and fixed-point dollars (new).
{
"price": 12,
"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)
- Legacy integer cents price fields (e.g.,
yes_bid, no_ask, last_price) will be deprecated on March 12, 2026. Their _dollars equivalents (e.g., yes_bid_dollars, no_ask_dollars, last_price_dollars) are already available
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.
Price Level Structures
| Structure | Ranges | Tick 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.
Fractional Contracts
Contract count fields are transitioning from integers to fixed-point strings.
{
"count": 10,
"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
Starting the week of March 9, 2026, fractional trading will be enabled on a limited per-market basis. Check the fractional_trading_enabled field on Market responses to determine whether a given market supports fractional order sizes.
For fractional-enabled markets, the legacy integer count fields (e.g., count, remaining_count) should not be relied upon. Between fractional enablement (week of March 9, 2026) and legacy-field removal (March 12, 2026), they may still appear but will contain truncated values; after March 12 they will no longer be returned. Migrate to their _fp equivalents to avoid data loss.
_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.
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. 