When you swap one coin for another on an instant exchange, there is a gap between the moment you create the order and the moment your deposit is confirmed. Bitcoin may take 10 to 60 minutes to confirm; even fast networks need a few minutes once you count the time to open your wallet and send. Prices keep moving during that gap. The rate type decides who absorbs that movement: you or the service.
What a floating rate means
With a floating rate, the quote you see is only an estimate. The final amount you receive is calculated when your deposit is confirmed, using the market price at that moment. If the price moved in your favor, you get more. If it moved against you, you get less.
Floating quotes are often a little better on screen, because the service does not have to price in the risk of the market moving. The trade-off is uncertainty: you do not know the exact result until the swap is done.
What a fixed rate means
With a fixed rate, the amount you will receive is locked when you create the order, as long as you send the agreed deposit within the time window. Whatever the market does during that window, the number on your order page is the number you get.
The service carries the price risk during the lock, so a fixed quote can include a small margin for that. In exchange, you get certainty, which is especially valuable for volatile coins and for larger amounts.
Slippage, in plain words
Slippage is the difference between the price you expected and the price you actually got. On a floating-rate swap, slippage is part of the deal: the longer your deposit takes and the more volatile the pair, the bigger it can be. On a fixed-rate swap, slippage within the lock window is zero by design, because the outcome was agreed in advance.
Side-by-side comparison
| Fixed rate | Floating rate | |
|---|---|---|
| Amount you receive | Known when the order is created | Known only after confirmation |
| Who carries price risk | The service, during the lock | You |
| Slippage | None within the window | Possible, up or down |
| Time pressure | Must deposit before the lock expires | Usually more relaxed |
| Best for | Volatile coins, larger amounts, exact payments | Small amounts, stable pairs, flexible timing |
When each type suits you
Choose fixed if
- You need an exact amount on the other side, for example paying someone 500 USDT.
- You are swapping a volatile coin and the deposit will take a while to confirm, as with BTC.
- You simply prefer to know the result before you send anything.
A floating rate can suit you if
- The amount is small and a few dollars of movement does not matter.
- You are swapping between two assets that move together, such as two stablecoins.
- You are comfortable taking market risk in exchange for a possibly better quote.
How LarkSwap handles rates
To be direct about it: LarkSwap offers fixed rates only. There is no floating option. Every order locks the rate for 30 minutes from the moment you create it, and the quote already includes the flat 0.4 % fee. A small payout network cost, such as about $1.50 for USDT on TRC20, is deducted from what you receive and is shown before you confirm.
The practical rule is to send your deposit well inside those 30 minutes, ideally right after creating the order. Delivery typically follows within 5 to 30 minutes once the deposit has enough confirmations, with Bitcoin usually the slowest because of its block times.
What if you pay late?
If your deposit arrives after the 30-minute lock has expired, the order is reviewed manually. Depending on the situation, it is either processed at the current market rate or refunded. Adding a refund address when you create the order makes that second path simpler. And if you have sent but the order does not show your deposit, you can paste the transaction hash on the order page.
Practical tips for fixed-rate orders
- Have your wallet open before you create the order. That way the 30 minutes are spent sending, not searching for a seed phrase.
- Send the exact amount. The unique decimals identify your payment. If your exchange deducts a withdrawal fee, add it on top.
- Use a normal or high network fee for BTC. A very low fee rate can leave your transaction waiting in the mempool past the window.
- Do not reuse an old order. If the lock has expired and you have not sent yet, create a fresh order with a fresh quote.
You can see a fixed quote in action on the BTC to USDT pair, or compare it with ETH to USDT. For a full walk-through of the first one, read how to convert BTC to USDT, and if speed is your priority, the fast crypto swap page explains typical timings.
Frequently asked questions
Does LarkSwap offer a floating rate?
No. LarkSwap uses fixed rates only. The rate is locked for 30 minutes from the moment you create the order, and the amount you will receive is shown before you send anything.
Is a fixed rate always more expensive than a floating rate?
Not necessarily. A fixed quote may include a small margin for price risk, but a floating rate can end up lower if the market moves against you while your deposit confirms. The fixed rate trades a possible upside for certainty.
What happens if my BTC confirms after the 30 minutes?
A payment that arrives after the 30-minute lock is reviewed manually and is either processed at the current rate or refunded. To avoid that, send right after creating the order and use a normal or high network fee so the transaction is picked up quickly.