> ## Documentation Index > Fetch the complete documentation index at: https://docs.calibri.io/llms.txt > Use this file to discover all available pages before exploring further. # Fees > Calibri charges a single taker fee, once, at the moment of the trade — price-dependent, highest at 50/50 and falling toward zero at the extremes. Makers pay nothing, and there is no settlement fee. Calibri's trading cost is deliberately simple: **one fee, charged once, when your order fills.** There is no settlement fee, no redemption fee, and makers pay nothing. * **One fee, at the trade** — A single **taker fee** is charged the moment your order fills. Nothing is taken again at settlement — winners redeem the **full 1.00 USDC per share**. * **Makers pay nothing** — Only the **taker** (the side that crosses the book to fill a resting order) pays. If your resting order gets filled, you pay **no** fee — and you may even earn a [maker rebate](/concepts/maker-rebates). ## How the taker fee is calculated The fee is **not** a flat percentage of what you spend. It scales with how uncertain the market is, peaking at price `0.50` and falling to zero at the extremes: ``` fee = rate × volume × P × (1 − P) ``` where **P** is the trade price (0–1), **volume** is the number of contracts, and **rate** is the taker rate for that market's category. The `P × (1 − P)` term is a bell curve. It is `0` at the edges, rises to its maximum of `0.25` at a coin flip, and is symmetric about `0.50` — so: * You pay the **most** on **coin-flip prices** (near `0.50`). * You pay **very little** on **lopsided prices** (near `0.05` or `0.95`) — a near-certain outcome is cheap to trade. * The fee **scales with your fill size**. This is the same formula Polymarket publishes. ### Relative fee across prices Holding rate and size fixed, the fee at each price relative to its maximum (at `P = 0.50`): | Trade price P | `P × (1 − P)` | Fee vs. the 50/50 maximum | | - | - | - | | `0.05` / `0.95` | `0.0475` | 19% | | `0.10` / `0.90` | `0.09` | 36% | | `0.25` / `0.75` | `0.1875` | 75% | | `0.50` | `0.25` | 100% (highest) | The curve is symmetric: `P` and `1 − P` give the same value, so a trade at `0.30` and a trade at `0.70` carry the same fee. ### Worked example Buying **100 contracts** of YES at `0.60` in a **Crypto** market (taker rate **7.00%**): ``` P × (1 − P) = 0.60 × 0.40 = 0.24 fee = 0.07 × 100 × 0.24 = 1.68 USDC ``` Your stake is `0.60 × 100 = 60.00 USDC`, so the fee works out to **2.80% of what you put in** — below the headline rate, because the curve tops out at `0.25` and `0.60` is off the midpoint. ### The fee is set aside when you place the order The maximum fee your order could incur is reserved **alongside** your collateral the moment you place, so a fee is never taken out of the stake backing a contract. Anything left over is released when the order fills, rests, or is cancelled. * A **limit** order reserves the fee at its own limit price. * A **post-only** order reserves **nothing** — it can only ever be a maker, and makers pay no fee. Practically: an order needs `stake + maximum fee` available, not just the stake. On the example above that is `60.00 + 1.68 = 61.68 USDC`. ## Taker rates by category The rate is resolved per market: an event-specific override if one is set, otherwise the market category's rate. | Category | Taker rate | | - | - | | Crypto | 7.00% | | Culture | 5.00% | | Economics | 5.00% | | Science | 5.00% | | Weather | 5.00% | | Other | 5.00% | | Sports | 5.00% | | Finance | 4.00% | | Mentions | 4.00% | | Politics | 4.00% | | Tech | 4.00% | | Geopolitics | 0.00% | | World | 0.00% | A market whose category carries a `0.00%` rate is **free to take** — no fee is charged and no rebate or referral reward is generated from it. The resolved rate is also carried in the market data the app reads, so the figure shown in the order ticket is always the one that will be applied. Read the rate as the input to the formula above, **not** as a flat percentage of your stake. Because it is multiplied by `P × (1 − P)` — at most `0.25` — the effective cost is always a fraction of the headline rate, and smaller still away from the middle. ## Where the fee goes The taker fee is the only money the platform takes from a trade, and it also funds both reward programmes: | Share | Goes to | | - | - | | **15% / 20% / 25% of the fee**, by category | The **maker** on the other side of your fill, as a [rebate](/concepts/maker-rebates) | | A **percentage of the fee**, by category | Your **referrer**, if you were referred | | The remainder | Platform revenue | The maker's share is set per category — **20%** in Crypto, **15%** in Sports, **25%** everywhere else. See [Maker rebates](/concepts/maker-rebates) for the full table. The referral share is likewise set per category and published in the rewards schedule — see the [referral program](/rewards-referral-program). Both rewards are a percentage **of the taker fee**, not of your stake — so on the 1.68 USDC Crypto example above, the maker earns `0.20 × 1.68 = 0.336 USDC`. Neither is paid at the moment of the trade: each fill records a reward, and a **daily payout** settles them. Markets in a `0.00%` category generate no fee, and therefore no rewards. ## Currency and rounding * All fees are denominated in **USDC** (6 decimals — one base unit is `0.000001 USDC`). * The fee is computed from the formula, then converted to base units and **rounded up**. A fee smaller than one base unit rounds up to the minimum unit (or is skipped entirely when the rate is zero). ## How the fee is collected The fee is **pulled on-chain from your Safe** to the operator at settlement. Your Safe pre-approved this during setup, so you only ever *sign* — the operator pays the gas. See [Self-custody](/non-custodial/overview) for the full model. ## What you are **not** charged | | | | - | - | | Maker fee | **None.** Only the taker pays — and the maker earns a [rebate](/concepts/maker-rebates) | | Settlement / redemption fee | **None.** Winners redeem the full `1.00 USDC` per share | | Deposit fee | **None on Polygon.** Funding is an ordinary on-chain transfer to your Safe; you pay only the network's gas to send it. USDC sent on another network carries a [bridge fee](#deposits-from-other-networks), capped unless you accept a higher one | | Withdrawal fee | **None on Polygon.** Moving USDC out of your Safe is relayed for you and the operator pays the gas. A withdrawal to another network carries a [withdrawal fee](#withdrawals-to-other-networks) | ## Deposits from other networks Depositing USDC **on Polygon is free**, with no minimum. USDC you send to your Safe address on **Ethereum, Base, Arbitrum or Optimism** is bridged to your Safe on Polygon, and that bridge carries one fee. It is not a trading fee and is not shared with makers or referrers: * **It covers network gas** — the bridge transaction on the network you sent from, the delivery on Polygon, and, on your first bridge from a network, creating your Safe there. * **At most 10 USDC, and at most 20% of the amount** bridged. Both caps are fixed in the bridge contract; Calibri cannot raise them. * **Above the cap only with your acceptance.** When gas — mostly on Ethereum — costs more than the caps allow, the deposit waits and the Wallet page shows the fee it would cost now. You can accept it and bridge now, or wait: we bridge automatically at the standard fee once it covers the cost. A fee you accept is taken from that deposit and is non-refundable once the bridge is sent. See [When Ethereum gas is high](/non-custodial/deposits-from-other-networks#when-ethereum-gas-is-high). * **One fee per bridge.** Below the network's minimum — **20 USDC on Ethereum, 5 USDC on Base, Arbitrum and Optimism** — deposits wait and are combined, then bridged together for one fee. * **Taken before the bridge**, in USDC, on the network you sent from. The rest is what arrives in your Safe on Polygon. * **Circle charges nothing** for its Standard transfers today. If that changes, Circle's own fee comes out of the amount it mints on Polygon. The Wallet page shows the current estimate for each network before you send. If anyone bridges your USDC before Calibri does — including you, which you can do at any time — no fee is charged on what they move. See [Deposits from other networks](/non-custodial/deposits-from-other-networks). **Deposit on Polygon to avoid this fee.** USDC sent on Polygon is credited directly, with no bridge, no fee and no minimum. ## Withdrawals to other networks Withdrawing USDC **on Polygon is free**, with no minimum. A withdrawal from your Safe to an address on **Ethereum, Base, Arbitrum or Optimism** goes through Circle's bridge and carries one fee. It is not a trading fee and is not shared with makers or referrers: * **It covers the cost** — the transaction on Polygon and the delivery on the destination network — **plus a margin**. * **At least 3 USDC to Ethereum, and at least 0.50 USDC to Base, Arbitrum and Optimism.** There is **no maximum**: the fee follows gas on the destination network. * **Shown before you sign.** The withdraw form shows the fee and what you receive, and the fee is part of the transaction you sign. You are never charged more than that — if gas rises after you send it, we complete the delivery at our own cost. * **Taken before the transfer**, in USDC on Polygon. The rest is what arrives at your address. * **Minimum withdrawals** are **20 USDC to Ethereum** and **5 USDC to Base, Arbitrum and Optimism**. * **Non-refundable** once the withdrawal is sent. See [Withdrawals to other networks](/non-custodial/withdrawals-to-other-networks). **Withdraw on Polygon to avoid this fee.** A withdrawal on Polygon has no fee and no minimum, and many exchanges accept USDC on Polygon. ## In short > You pay a single **taker fee** when your order fills — **never again** at > settlement. **Makers pay nothing** and earn a rebate. The fee is highest around > 50/50 prices, near-zero on lopsided prices, and scales with your fill size. The > rate depends on the market's category (0%–7%). ## Related The share of this fee paid back to the maker, on the same curve. Prices as probabilities and how settlement pays out. Read resolved fees programmatically in the API Reference. The bridge fee, minimums and timing for USDC sent on another network. The withdrawal fee, minimums and timing for USDC sent to another network. This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.