Fixed vs Floating Exchange Rates Explained

A fixed exchange rate is set in advance and stays the same for an agreed period; a floating exchange rate moves with supply and demand. In crypto, the difference shows up every time you swap: a fixed-rate swap locks the quote before you send funds, while a floating-rate swap gives you whatever the market rate is when your trade is executed. Stablecoins add a third model, the peg, which aims to keep a token close to the value of a currency such as the US dollar or the euro.

Key takeaways

• A fixed rate gives you a known amount but usually costs a little more, because the provider carries the market risk while the quote is valid.
• A floating rate follows the market and can turn out better or worse than the initial estimate.
• A peg is a target, not a promise: stablecoins can trade below their reference value, as USDC did in March 2023.
• Only eligible customers, usually institutions, can redeem major stablecoins directly with the issuer, so most users rely on the market price during a depeg.
• The rate is only one part of the cost: spreads, platform fees and network fees all reduce the amount you receive.

In practice, crypto exchange rates are affected by much more than the headline price on a chart. The price shown is usually a mid-market or last-traded price; the rate you get includes the provider's spread, depends on how much liquidity is available for your trade size, and can change between the moment you see it and the moment your trade is executed. Two services can therefore quote different amounts for the same pair at the same time without either being wrong.

Time is the main source of friction. When you swap on a service that needs your crypto to arrive first, your deposit has to be confirmed on the blockchain, which can take from seconds to an hour depending on the network. During that period the market keeps moving. A 0.5% move is easy to ignore on a €100 swap but means a €50 difference on €10,000, which is why businesses converting crypto revenue into euros pay close attention to how rates are set.

The terms come from traditional finance, where they describe the currency rate mechanisms used by central banks. Sterling and the euro float: their value against other currencies is set by the market. The Hong Kong dollar has been pegged to the US dollar since 1983 and is kept within a band of 7.75 to 7.85 per dollar. Pegs can also end abruptly: on 15 January 2015, the Swiss National Bank dropped its minimum rate of 1.20 francs per euro, and the franc jumped sharply within minutes.

Crypto uses the same ideas on a smaller scale and over shorter periods:

The fixed vs floating exchange rate trade-off is the same in both worlds: certainty against cost and flexibility. Choosing a fixed exchange rate gives you a predictable result, but someone else has to carry the risk of the market moving, and they charge for it. Choosing a floating exchange rate avoids that charge and lets you benefit if the market moves your way, but you accept that the result may be worse than expected.

For a crypto swap, this means a fixed quote is usually slightly less favourable than the floating estimate shown at the same moment. Whether that premium is worth paying depends on how much an adverse move would hurt you.

A pegged exchange rate links an asset to a reference value and relies on a mechanism to keep it there. For a central bank, that mechanism is buying and selling its own currency with its reserves. For fiat-backed stablecoins such as USDT and USDC, it is a combination of reserves held by the issuer, the issuer's willingness to issue and redeem tokens at 1:1, and traders who profit from small deviations.

If a stablecoin trades below $1, a trader who can redeem with the issuer buys it cheaply on the market and redeems it for a full dollar, pushing the price back up. If it trades above $1, the trader buys new tokens from the issuer at $1 and sells them on the market. In the EU, MiCA classifies a stablecoin pegged to a single official currency as an e-money token and gives holders a right to redeem it from the issuer at par value. Before relying on a particular stablecoin in the EU, check its current status in the ESMA register.

A stablecoin peg is only as strong as confidence in the reserves and the ability to redeem. Depegging happens when sellers outnumber buyers at the target price and the arbitrage that normally restores it is too slow, too limited or doubted. Common triggers are concerns about the reserves, problems at a bank holding them, or a sudden wave of redemptions.

The best-known recent case of a fiat-backed stablecoin depegging came in March 2023. After Circle disclosed that $3.3 billion of USDC's reserves were held at the failed Silicon Valley Bank, USDC fell to about $0.88 on secondary markets. It returned close to $1 within days, once US authorities said all of the bank's deposits would be protected. Algorithmic stablecoins without full reserves can fail completely, as TerraUSD did in May 2022.

Direct redemption is not open to everyone. Tether lists a minimum redemption of $100,000 and a fee of 0.1% or $1,000, whichever is greater, for verified customers, while Circle Mint, the service for issuing and redeeming USDC, is for institutions rather than individuals. Most users can only sell on the market, at whatever price it offers during a depeg. For businesses that accept crypto payments and convert them into euros, even a short deviation can create a cash shortfall: €100,000 of invoices paid in a stablecoin trading at $0.97 converts into roughly 3% fewer euros than expected.

The amount you receive depends on several layers of cost, not only on the crypto swap rate shown:

On Ethereum, network fees depend on how much gas a transaction uses and on the base and priority fees at that moment, so sending a token costs more than sending ETH. These fees are separate from the exchange rate and are paid even if the rate itself is fixed.

On swap and exchange services, the two options differ in who carries the risk while your deposit is confirmed:

A floating rate swap makes sense when the amount is small, the pair is liquid and the deposit will confirm quickly. You avoid paying for rate protection and receive the market rate at execution. If the market moves in your favour, you keep the gain; if it moves against you, you absorb the loss. Floating rates are also the default on most decentralised exchanges, where the slippage tolerance you set is the only limit on how far the price can move.

It makes sense to lock the exchange rate when the exact result matters more than the last fraction of a per cent: paying an invoice, converting a large amount, or swapping during volatile markets. You accept a quote, send the exact amount within its validity window, and receive the agreed sum. The protection only lasts as long as the quote: a fixed rate swap does not shield you from a stablecoin depeg or a price fall that happens before you request the quote or after the trade is settled.

Behind the scenes, fixed vs floating crypto exchange models rely on different ways of finding liquidity. A floating swap on a decentralised exchange is executed against an automated market maker pool or an order book at the moment the transaction is included in a block, so the price can keep changing until then. A floating swap on a centralised service is executed from the provider's liquidity once your deposit is confirmed.

There is no single best model; the right choice depends on the transaction. Use these questions before you confirm a swap:

Also check the network fee separately from the rate, and expect larger conversions to trigger additional verification or source-of-funds questions. Businesses that receive crypto regularly and keep both crypto and euro balances, for example in a multicurrency business account, often decide on a standard approach in advance, such as fixed quotes for supplier payments and floating rates for small top-ups.

ABF Swap's instant crypto swap converts supported crypto assets into euros or other supported assets, and the company states that the rate it shows is final and already includes its fee. As with any service, check the quoted rate, the amount you will receive, the network for any deposit or withdrawal and the destination details before confirming. Network fees for on-chain deposits and withdrawals are charged separately by the blockchain.

This article is for general educational purposes and does not constitute financial, investment, legal or tax advice. Cryptoassets, including stablecoins, are high-risk, their value can fall to zero, and transfers are generally irreversible. In the UK, cryptoassets are generally not protected by the FSCS, and you may not be able to complain to the Financial Ombudsman Service; in the EU, they are not covered by deposit guarantee schemes. Rules on cryptoasset services differ by country, so check whether any provider you use is authorised to serve customers where you live.