Fees

What placing an order locks

A reservation is not a fee. It is your own money moved from available to locked the moment an order is accepted, and released in full if the order never fills. It is also the number that decides whether an order can be placed at all, which makes it the first cost anyone actually meets.

Funds are reserved at placement, not at fill. Without that, two orders each pass their own balance check against the same money and both rest; whichever fills second overdraws an account that looked solvent to both of them.

• Spot limit buy

  engine/reserve.ts

  Limit price × quantity, in the quote asset. Exact, never rounded — the most the order can ever cost, because a limit buy cannot fill above its price.

  Fee not reserved. The fee comes out of the base that arrives, so reserving for it would lock quote the order will never spend.

• Spot limit sell

  engine/reserve.ts

  The quantity itself, in the base asset. Nothing is reserved in the quote asset at all.

  Fee not reserved. The fee comes out of the quote that arrives, which the order does not hold yet.

• Spot market order

  engine/lifecycle.ts

  Nothing. It fills in the same breath as it is placed and never rests, so it spends straight out of available — placement only checks that available covers the walk it just planned.

  Fee not reserved. It comes out of the asset the fill delivers, so it is never part of what the order has to be able to afford.

• Perpetual — the part that rests

  engine/futures.ts

  Initial margin plus the 0.05% fee on the resting quantity, priced at the order's own limit. That is the reservation rule: margin and fee together, in one number, for every non-reduce-only order.

  Fee reserved. Both are charged in the quote asset the order is already reserving, and a fill with no fee reserved would have nothing to pay from.

• Perpetual — the part that fills now

  engine/futures.ts

  Nothing is locked. Placement instead checks that available covers margin plus fee at the price the order actually plans to fill at — not at its limit, because a sell that fills above its limit produces a larger notional and needs more margin, not less.

  Fee reserved. It is part of the affordability check, then paid straight out of available when the fill settles.

• Perpetual — reduce-only

  engine/futures.ts

  Nothing. The position it reduces is its funding.

  Fee not reserved. The fee is taken out of the margin released by the close, so nothing has to be set aside first.

The pattern down the right-hand side is the whole rule: a fee is reserved only when it is charged in the same asset the order is already holding. On spot it never is — the fee comes out of what arrives — so reserving for it would lock money the order cannot spend, and produce “insufficient funds” on an account with exactly enough. On a perpetual it always is, because margin and fee are both quote.

One fill, line by line

A 1 BTC market buy on BTCUSDT, from order to ledger. Every number below was produced when this page rendered, by the same two functions a real order runs: the matcher that walks the book and the settler that builds the legs. None of it is written down — change the fee rate and this section changes with it.

The fee is 0.001 BTC — 64.663425 USDT at the price it filled at. Clearing 3 levels rather than one cost a further 3.425 USDT against the best ask, which is 0.5297 bps — an order-book cost, not a charge, and on this order about a twentieth of the fee. It behaves differently from the fee in the way that matters: the rate is flat at any size, while the walk depends entirely on what the book is holding at that moment. On a deep pair at this size it is noise. On a thin one, or on a size that clears most of a side, it stops being noise, and no fee schedule can tell you which you are about to do.

Both assets sum to zero across those 5 rows, and a transfer that does not is refused before it reaches the database. That is why the fee has to be its own entry: there is no way to take money out of one account here without naming the account it went into.

The market is real and its filters are the venue’s — tick size 0.01, lot step 0.00001, minimum notional 5 USDT. The four book levels are illustrative: a live BTCUSDT ask side is far finer, and a one-BTC order routinely touches dozens of levels holding dust. Everything derived from those four levels is the engine’s own arithmetic.

Where the money goes

Every balance in this product is the sum of entries in one double-entry ledger. The ledger knows 10 buckets, and 6 of them are out of reach of anything on this page: three belong to the test-network settlement rail, two hold customer balances committed to the lending desk, and one holds house money already reserved to a reward campaign. That leaves the four below. Two of them are yours. Two have no owner at all, and one of those two is where every fee lands.

available

Yours, and spendable — one balance per wallet, per asset.

locked

Yours, but committed: a resting order’s reservation, or the margin behind an open position.

external

The outside world. No owner, and permanently negative by design — that number is what the exchange owes everyone outside it. Deposits, both sides of every fill, and funding all cross here.

fees

House revenue. Also owner-less, and the destination of all 7 fees in the schedule above; the test-network payout rail would settle its flat fee here too. It is not a dead end, and it is the one place on this page money runs backwards: 10% of every settled fill fee is claimable straight back out of it into a member’s spot wallet, and a reward campaign has to reserve its whole winner cap out of it, into the rewards bucket, before it is allowed to start. Both are on Rewards.

Naming the account is the disclosure. A fee that is described only as a percentage can be reconciled against nothing; a fee that is a leg addressed to fees can be summed, and it has to balance against the entry it came from or the transfer is rejected outright. Real exchanges do not publish this because their fee revenue is a business number. Ours is a schema.

What a round trip costs

Nobody trades one fill. The cost that decides whether a strategy survives is getting in and back out again — and on a leveraged position that cost is not the one on the rate card, because the rate is charged on the notional while the account only ever posted the margin.

Below is one 10,000 USDT perpetual position, opened and closed at the same price. The rate never changes down the table and neither does the amount of USDT it comes to. The last column runs from 0.10% to 7.50%, for the only reason it can: margin is notional divided by leverage, so the same 0.05% is a larger share of a smaller stake.

• 1×

  0.10% of margin

  Margin

  10,000 USDT

  Reserved to open

  10,005 USDT

  Both fees

  10 USDT

• 2×

  0.20% of margin

  Margin

  5,000 USDT

  Reserved to open

  5,005 USDT

  Both fees

  10 USDT

• 5×

  0.50% of margin

  Margin

  2,000 USDT

  Reserved to open

  2,005 USDT

  Both fees

  10 USDT

• 10×

  1.00% of margin

  Margin

  1,000 USDT

  Reserved to open

  1,005 USDT

  Both fees

  10 USDT

• 25×

  2.50% of margin

  Margin

  400 USDT

  Reserved to open

  405 USDT

  Both fees

  10 USDT

• 50×

  5.00% of margin

  Margin

  200 USDT

  Reserved to open

  205 USDT

  Both fees

  10 USDT

• 75×

  7.50% of margin

  Margin

  133.33333334 USDT

  Reserved to open

  138.33333334 USDT

  Both fees

  10 USDT

Margin is initialMargin, the reservation is marginWithFee — the function placement calls to size a lock — and both fees are takerFee at ledger precision. Funding and the book walk are excluded, and on a position held for more than a session funding is usually the larger of the two.

How far the price has to move to break even

Slightly further than twice the rate, and the gap is not rounding. The closing fee is charged on the closing notional, so a position that moved in your favour pays a bigger second fee than its first. Solve it and the required move is 2f / (1 − f) rather than 2f.

Perpetuals

0.1001%

the rise a long needs, against 0.10% of fees

0.1000% — the fall a short needs

Spot, in and back out

0.2003%

the rise a long needs, against 0.20% of fees

0.1999% — the fall a short needs

A short’s break-even move is marginally shorter for the mirror-image reason: it closes at a smaller notional, so its second fee is smaller. Both figures are rounded up — a required move that rounded down would tell you that you needed less than you do. Neither includes funding, the book walk, or the lot-step rounding two sections below.

Which way every number rounds

Rounding direction is not a detail here; it is the difference between an engine that settles and one that quietly leaks. Two rules carry most of it, and they point in opposite directions on purpose.

A quantity rounds down, because rounding one up asks an account to spend money it does not have — the order passes its own balance check and then fails at settlement, which is the worst possible place to discover it. A fee rounds up, because rounding one down means the house absorbs the remainder on every trade, and each individual shortfall is small enough to look like a rounding error rather than a leak.

• 0.011 BTC × 0.10%

  = 0.000011 exactly

  What is charged

  0.00002

  If it rounded down

  0.00001

  The house would absorb 0.00001 BTC on this one order. At volume that is a real number, and it never appears in any report because each shortfall looks like a rounding error.

• Selling a balance of 0.123456789 BTC

  = 0.123456789 exactly

  What is placed

  0.12345

  If it rounded up

  0.12346

  The order would offer 0.000003211 BTC the account does not hold. It passes its own balance check, rests, and fails at settlement — the worst possible place to find out.

Everything else follows the same principle: where a rounding has a beneficiary, the house is it. Every one of them is listed below, because a schedule that publishes a rate and hides its rounding has published the smaller half of the price.

• Fill quantity

  Down

  at the venue's lot step

  Taking more than a level holds would invent liquidity the venue never offered.

  engine/matching.ts

• Trading fee

  Up

  at the precision of the asset it is charged in

  The house would absorb the remainder on every trade, and each shortfall is small enough to look like a rounding error rather than a leak.

  engine/fees.ts

• Amount spent on a convert

  Down

  at 8 decimals

  Rounding a debit up spends money the account does not have.

  engine/convert.ts

• Amount credited by a convert

  Down

  at 8 decimals

  A credit that rounds up pays out value the rate did not produce.

  engine/convert.ts

• Initial margin

  Up

  at 8 decimals

  A position would sit on slightly less collateral than its leverage claims, and the shortfall would be the house’s.

  core/futures.ts

• Margin released by a partial close

  Down

  at 8 decimals

  Releasing more than the pro-rata share hands back margin the position still needs.

  engine/futures-plan.ts

• Realised PnL — a gain

  Down

  at 8 decimals

  Recorded PnL has to equal settled PnL exactly, so the gain shrinks toward zero rather than away from it.

  engine/futures-plan.ts

• Realised PnL — a loss

  Up

  at 8 decimals

  The same rule seen from the other side: a loss grows away from zero.

  engine/futures-plan.ts

• Funding you pay

  Up

  at 8 decimals

  Both funding directions round the same way the fee does.

  core/futures.ts

• Funding you receive

  Down

  at 8 decimals

  The mirror of the line above.

  core/futures.ts

One rounding costs more than the rate says

On a spot buy, the fee is charged in the base asset and rounded up at that market’s lot step — the same precision the venue uses for quantities. On BTCUSDT that step is 0.00001 BTC — so 0.00001 BTC is the smallest fee a BTC buy can be charged, however small the order is.

Below 0.01 BTC that floor is the whole fee, so the effective rate is a multiple of 0.10%. Above it the rounding usually costs nothing — but the 0.011 row is in the table deliberately: a several-hundred-dollar order is not automatically clear of it either. What decides the outcome is whether the fee lands on the lot grid, not whether the order feels large.

Scroll the table sideways for the fee and the effective rate.

Computed by calling the engine’s own takerFee at this market’s lot precision, priced at the example fill above. The floor is a spot-buy effect only: a sell, a convert and every perpetual charge round at 8 decimals in the quote asset, where a step that size is far below anything a fee can reach. If you are trading small size on spot, buy in round lots or use convert, which does not have this rounding.

Convert, against the two orders it replaces

Going from one asset to another on the spot book takes two market orders through USDT — two fees, two book walks, two spreads. A convert is one operation at one rate, and it is charged 0.10% once. On this product that genuinely is the cheaper route, which is the opposite of how the same button works nearly everywhere else.

The reason it is cheaper here is that there is nowhere to hide a markup. A retail convert usually quotes a rate with the venue’s margin already inside it, so the advertised zero fee is paid anyway and cannot be measured. Ours is each leg’s last traded price against USDT, divided — and the fee is a ledger leg addressed to fees, which is the only charge in the path.

The row worth reading twice is depth. A last price is not a tradeable price, and the same missing book that removes the spread also removes the slippage — so a convert of any size fills at that one rate. For a wallet-sized balance that is exact. For a size that would clear several levels of the real book it is a simplification in your favour, and the spot terminal is where the honest version of that trade lives.

The rate is re-derived on the server at execution and compared against the one you were shown. Beyond 50 bps in either direction the conversion is refused and your balance is untouched — a rate that moved in your favour is still not the trade you agreed to. A convert whose result would be nothing after the fee is refused too, rather than executed for zero.

What a liquidation costs

A position is liquidated when its equity — margin plus unrealised PnL, measured at the venue’s mark price rather than at the last trade — falls to or below maintenance margin. That is a flat 0.50% of notional, with no tiered brackets and no size-dependent schedule. The engine then closes the position at the mark and charges the ordinary perpetual rate, 0.05%, on quantity × mark. There is no separate penalty on top of a perpetual liquidation.

A lending liquidation is the other engine and works the other way. It is not a rate on a fill: the desk sells the collateral at a fresh server mark and keeps 5.00% of what it marked at before settling the debt, which is a penalty in the sense this section says perpetuals do not have. Any surplus after the debt goes back to the borrower, and a mark that would not cover the debt after the penalty is refused outright rather than settled at a loss to the pool.

The order the arithmetic runs in is the part worth knowing. Margin, plus realised PnL, minus the fee — and the result is floored at zero. A loss can consume the whole margin you posted, and the fee can consume what is left of it, but neither can reach past it. Anything beyond the margin is absorbed by external, and that is the whole meaning of isolated margin: the most a position can cost you is the margin standing behind it.

A mark price older than sixty seconds is not used at all. The sweep reports the symbol as degraded and skips it, because a stale price must never settle anything — and a liquidation is the least reversible thing this engine does.