> ## Documentation Index
> Fetch the complete documentation index at: https://docs.kairos.trade/llms.txt
> Use this file to discover all available pages before exploring further.
# Fees
> Kairos platform fee policy — live fee tiers, per-venue exchange fees, and fee quotes
Two separate charges can apply to a fill: the **Kairos platform fee**, set by your fee tier, and the **venue's own exchange fee**, set by the exchange. They are computed independently and reported separately. This page explains how each is calculated and where to read the live numbers.
**Never assume either charge is zero.** Price an order with the
[Fee Quote endpoint](/rest/orders#fee-quote), which returns both
components plus the all-in cost.
| Charge | Set by | Basis | Where to read it |
| - | - | - | - |
| Platform fee | Kairos, via your fee tier | Basis points on notional | `fees.getUserTier` / `fees.getFeeTiers` |
| Exchange fee | The venue | A per-venue formula (below) | Fee quote, or the venue's own schedule |
## Kairos Platform Fee
Your platform fee uses the maker or taker schedule from the fee tier that
applies to you at fill time. A tier can use a flat rate:
```text theme={null}
platform fee = notional × bps / 10,000
```
where `notional = fill quantity × fill price`. Maker and taker carry separate
rates, so a resting limit order and a marketable order on the same market can
be charged differently.
A curve tier instead stores ordered `{ price, feeBps }` control points for each
side. Kairos linearly interpolates the effective basis-point rate at the fill's
actual share price, then applies that rate to notional. Curves cover the complete
price range from `0` through `1`; the `makerFeeBps` and `takerFeeBps` fields on a
curve tier expose its peak rates for backwards-compatible displays. Read
`feeModel`, `makerFeeCurve`, and `takerFeeCurve` to price the full schedule.
A parabolic tier stores an edge rate and a center rate for each side. For a fill
price `p` between `0` and `1`, Kairos evaluates the exact symmetric schedule:
```text theme={null}
effective bps = edge bps + 4 × (center bps − edge bps) × p × (1 − p)
```
The configured edge rate applies at `p = 0` and `p = 1`; the configured center
rate applies at `p = 0.50`. Read `makerFeeEdgeBps`, `makerFeeCenterBps`,
`takerFeeEdgeBps`, and `takerFeeCenterBps` when `feeModel` is `parabolic`.
### How volume tiers apply
Your rolling 7-day and 30-day matched volume determines your position on the
volume ladder. Tier changes take effect on the next fill, and volume tiers are
recomputed as your rolling volume changes.
## Live fee schedule
Rendered from the live `fees.getFeeTiers` configuration. Last schedule update: **2026-09-02T03:28:36Z**. Rates are configuration, not a fixed schedule — the fee quote shown before an order is authoritative.
### Volume ladder
| Tier | 7-day volume | 30-day volume | Rate model | Gas |
| - | - | - | - | - |
| [Kairos Starter](#kairos-starter) | \$0 | \$0 | Parabolic | Sponsored |
| [Kairos Bronze](#kairos-bronze) | \$0 | \$50,000 | Parabolic | Sponsored |
| [Kairos Silver](#kairos-silver) | \$0 | \$99,900 | Parabolic | Sponsored |
| [Kairos Gold](#kairos-gold) | \$0 | \$1,000,000 | Parabolic | Sponsored |
Gas sponsorship for a tier is typical, not a billing guarantee — availability depends on your wallet and chain integration. See the [glossary](/learn/glossary).
### Kairos Starter
* **7-day volume** — \$0
* **30-day volume** — \$0
* **Network gas** — Sponsored
* **Maker rate** — `0 + 4 × (0 − 0) × p × (1 − p) bps`
* **Taker rate** — `10 + 4 × (50 − 10) × p × (1 − p) bps`
| Fill price | Maker rate | Taker rate | Taker fee on 100 shares |
| - | - | - | - |
| 10¢ | 0 bps | 24.40 bps | \$0.0244 |
| 25¢ | 0 bps | 40 bps | \$0.1000 |
| 50¢ | 0 bps | 50 bps | \$0.2500 |
| 75¢ | 0 bps | 40 bps | \$0.3000 |
| 90¢ | 0 bps | 24.40 bps | \$0.2196 |
### Kairos Bronze
* **7-day volume** — \$0
* **30-day volume** — \$50,000
* **Network gas** — Sponsored
* **Maker rate** — `0 + 4 × (0 − 0) × p × (1 − p) bps`
* **Taker rate** — `9 + 4 × (40 − 9) × p × (1 − p) bps`
| Fill price | Maker rate | Taker rate | Taker fee on 100 shares |
| - | - | - | - |
| 10¢ | 0 bps | 20.16 bps | \$0.0202 |
| 25¢ | 0 bps | 32.25 bps | \$0.0806 |
| 50¢ | 0 bps | 40 bps | \$0.2000 |
| 75¢ | 0 bps | 32.25 bps | \$0.2419 |
| 90¢ | 0 bps | 20.16 bps | \$0.1814 |
### Kairos Silver
* **7-day volume** — \$0
* **30-day volume** — \$99,900
* **Network gas** — Sponsored
* **Maker rate** — `0 + 4 × (0 − 0) × p × (1 − p) bps`
* **Taker rate** — `8 + 4 × (30 − 8) × p × (1 − p) bps`
| Fill price | Maker rate | Taker rate | Taker fee on 100 shares |
| - | - | - | - |
| 10¢ | 0 bps | 15.92 bps | \$0.0159 |
| 25¢ | 0 bps | 24.50 bps | \$0.0612 |
| 50¢ | 0 bps | 30 bps | \$0.1500 |
| 75¢ | 0 bps | 24.50 bps | \$0.1837 |
| 90¢ | 0 bps | 15.92 bps | \$0.1433 |
### Kairos Gold
* **7-day volume** — \$0
* **30-day volume** — \$1,000,000
* **Network gas** — Sponsored
* **Maker rate** — `0 + 4 × (0 − 0) × p × (1 − p) bps`
* **Taker rate** — `5 + 4 × (25 − 5) × p × (1 − p) bps`
| Fill price | Maker rate | Taker rate | Taker fee on 100 shares |
| - | - | - | - |
| 10¢ | 0 bps | 12.20 bps | \$0.0122 |
| 25¢ | 0 bps | 20 bps | \$0.0500 |
| 50¢ | 0 bps | 25 bps | \$0.1250 |
| 75¢ | 0 bps | 20 bps | \$0.1500 |
| 90¢ | 0 bps | 12.20 bps | \$0.1098 |
## Exchange Fees
Venue fees are charged by the exchange, not by Kairos, and are on top of the
platform fee. Polymarket and Predict.fun charge **takers only** — a resting
maker order pays no exchange fee there. Kalshi is the exception.
### Polymarket
```text theme={null}
fee = shares × rate × p × (1 − p)
```
`p` is the share price and `rate` is the market's category fee curve. The fee
peaks at `p = 0.50` and tapers toward both extremes, and the result is rounded
to five decimal places.
| Category | Rate | Taker fee per 100 shares at 50¢ |
| - | - | - |
| Crypto | 0.07 | \$1.75 |
| Sports, Economics, Culture, Weather, Other | 0.05 | \$1.25 |
| Finance, Politics, Mentions, Tech | 0.04 | \$1.00 |
| Geopolitics | 0 | \$0.00 |
Markets with fees disabled charge nothing regardless of category. These rates
mirror Polymarket's published schedule and can change on their side.
**A resting Polymarket buy still needs balance headroom for a fee it may never
pay.** Polymarket's CLOB **reserves** the taker-fee estimate at placement even
for an order expected to rest. The fee quote reports this separately as the
venue reserve.
### Predict.fun
```text theme={null}
fee = (feeRateBps / 10,000) × min(p, 1 − p) × shares
```
`feeRateBps` is per market and read from live market metadata. When it cannot
be resolved, the quote falls back to a 200 bps (2%) base and flags itself as an
estimate. Like Polymarket's curve, the fee peaks at `p = 0.50`.
### Kalshi
```text theme={null}
fee = scale × contracts × p × (1 − p)
```
The `scale` depends on the market's series ticker — the part before the first
`-`. Unknown series fall back to Standard.
| Series tier | Maker scale | Taker scale | Taker fee per 100 contracts at 50¢ |
| - | - | - | - |
| Standard | 0 | 0.07 | \$1.75 |
| Non-standard (most sports and macro) | 0.07 | 0.0175 | \$0.44 |
| Index (S\&P 500 / Nasdaq) | 0 | 0.035 | \$0.88 |
| Fee-free series | 0 | 0 | \$0.00 |
> **On the non-standard series the inversion bites: the *maker* pays the higher
> scale.** Resting an order there is the expensive side, not the cheap one.
> **Kalshi fee quotes are estimates.** Kalshi does not expose a fee API, so
> Kairos maintains this schedule by hand from Kalshi's published table. Confirm
> against Kalshi's published schedule for anything rate-sensitive.
## Fee Quotes
`GET /orders/fee-quote` prices a hypothetical order against the live book and
returns the platform fee, the exchange fee, the venue reserve, the total fee,
and the all-in cost — see [Fee Quote](/rest/orders#fee-quote). Fee quotes
are supported for `kalshi`, `polymarket`, and `predictfun`.
Quotes are marked as estimates: they price off a point-in-time book, and a
market order's realised average price (and therefore its fee) depends on what
the book looks like at execution.
For a live stream of quotes as you size an order, subscribe to
`subscribe_fee_quote` on the order-execution socket — see
[Fee Quote WebSocket](/websocket/fee-quote).
## Network Costs
Beyond exchange fees, on-chain venues can carry network costs and collateral
conversion steps that are not Kairos platform fees.
**The fee quote's total cost covers the platform and exchange fees only** — it
does not include network or conversion costs.
This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.