Short answer: choose a fixed rate when the market is moving fast, the amount matters to you, or your deposit chain is slow to confirm. Choose a floating rate when the market is calm and you send on a fast chain — on average it delivers slightly more, because you are not paying for insurance.
What each one actually is
A floating rate is recalculated at the moment your deposit is confirmed and the swap executes. Whatever the market does in the meantime, good or bad, lands on you.
A fixed rate locks the quoted number for a defined window, usually a handful of minutes. If the market moves against the service during that window, it absorbs the difference. That protection is not free: it is priced into a slightly less generous quote.
Comparison
| Fixed rate | Floating rate | |
|---|---|---|
| Amount you receive | Known before you send | Known at execution |
| Cost | Slightly worse quote | Best available quote |
| Market drop during confirmation | You are protected | You receive less |
| Market rise during confirmation | You do not benefit | You receive more |
| Time pressure | Must deposit within the window | None |
| Best when | Volatile market, slow chain, larger amount | Calm market, fast chain, small amount |
The variable people forget: confirmation time
The rate type only matters for as long as your deposit is unconfirmed. That window is set by the chain you send from:
- Solana, Tron, BNB Chain, most L2s — seconds. Market risk is negligible, and floating is usually the sensible default.
- Litecoin, Dogecoin — a couple of minutes. Mild exposure.
- Ethereum — minutes, longer if you set a low fee.
- Bitcoin — 10 to 30 minutes and occasionally much more. This is where a fixed rate earns its premium.
Sending BTC with a low fee during a volatile day is precisely the scenario a fixed rate exists for.
A rule of thumb
- Fast chain, calm market → floating.
- Bitcoin deposit, or a market moving several percent an hour → fixed.
- Amount large enough that a 2% swing would annoy you → fixed.
- Amount small and the difference is pocket change → floating, and do not overthink it.
Things to watch either way
- The window is real. A fixed rate that expires before your deposit confirms typically reverts to the market rate, which removes the benefit you paid for. Do not under-pay the network fee on a fixed-rate order.
- Send the exact amount. A deposit that differs from the quote often invalidates the lock.
- Compare final amounts, not rate types. The number that matters is what lands in your wallet after all network fees.
Key takeaways
- A fixed rate is insurance with a premium built into the quote.
- Your exposure lasts only as long as confirmation takes.
- Bitcoin deposits are the strongest case for locking.
- On fast chains in a calm market, floating wins on average.
Both options are available per order on the Cryptozilla calculator, and the estimated output updates as you switch between them.
Frequently asked questions
Why is the fixed rate always slightly worse?
Because the service takes on the market risk for the duration of the lock and hedges it. The difference between the two quotes is the price of that hedge.
What happens if the fixed-rate window expires?
The order usually falls back to the current market rate or is offered for a refund, depending on the service and how late the deposit arrives. Paying an adequate network fee is the way to avoid this.
Does a floating rate mean the rate can change after the swap?
No. It is fixed at the moment of execution. "Floating" refers only to the period between creating the order and confirming the deposit.
