Fees and Spreads Explained for the SSP Aggregator
Nobody shows you a bill. There is no line item that says "our cut." Instead, every buy, sell, and swap quote you see in SSP has costs folded into it in ways that are easy to miss — and the single most useful skill you can develop is knowing where to look.
The good news: there are only four places a fee can hide, and once you know them, reading a quote takes about five seconds.
The rate is not the price
Start here, because it's the mistake almost everyone makes.
When an exchanger or a fiat provider quotes you a rate, the spread is already inside it. They do not charge you the market price and then add a percentage. They quote you a slightly worse rate than the market and keep the difference. That's the spread, and it is the primary way these businesses make money.
The consequence is that comparing headline rates between providers tells you something, but comparing the amount that actually lands in your wallet tells you everything. That number — the output amount — already has the spread baked in. It is the only figure that cannot lie to you.
If you take one habit from this article: compare output amounts, not rates.
The four places a cost hides
1. The spread, inside the quoted rate
As above. Invisible by construction. It varies by provider, by pair, and by how liquid the assets are. Obscure pairs cost more. This is normal, not predatory — but it's why the aggregator quoting several exchangers at once is genuinely useful: you can see who's offering the best output for the same input, which is the spread revealing itself through competition.
2. The destination network fee
When you swap, the exchanger has to pay a network fee to deliver your bought asset on the destination chain. That cost is passed to you, and it appears as a distinct component of the quote.
This is why swapping into an asset on a congested, expensive chain costs more than swapping into the same asset on a cheap one — the delivery fee is different. It's also why small swaps into Ethereum mainnet assets can look brutally inefficient: a fixed delivery cost is a much bigger slice of a small trade.
3. The network fee on your own outgoing transaction
This one catches people, because it isn't part of the quote at all.
Remember what an in-wallet swap actually is: an ordinary send to the exchanger's deposit address. Ordinary sends cost network fees. You pay Bitcoin miners in sat/vB, or Ethereum validators in gas, exactly as you would sending to a friend — and that is on top of everything in the quote.
So the true cost of a swap is:
the spread (inside the rate) + the destination network fee (in the quote) + the network fee on your send (not in the quote)
The same is true of a sell: the fiat provider quotes you a rate, but you still pay the network fee to get your crypto to their deposit address. Budget for it. On UTXO chains this is where fee strategy matters; on EVM chains it's gas, and it's the reason the same swap can cost a few cents on one chain and a painful amount on another.
4. The fiat rail, on buys and sells
Card payments, bank transfers, and local payment methods do not cost the provider the same amount, and that difference reaches you. A card is typically instant and expensive; a bank transfer is typically slow and cheap. When a widget offers you several ways to pay, it is often offering you several different prices.
Fixed rate or floating rate
Swap quotes come in two flavours, and the difference is about when the price is decided.
A floating rate is provisional. It's the rate now, but the trade settles when your deposit confirms on-chain — which could be a minute later or, on a slow chain at a low fee, considerably longer. The final rate is whatever it is at settlement. If the market moves in your favour, you gain; if it moves against you, you lose.
A fixed rate is locked at quote time. The exchanger takes on the market risk between your send and their payout, and they charge you for it — a fixed-rate quote is normally a little worse than the floating one at the same moment. That's the premium for certainty.
Neither is a trick. It's a straightforward trade:
- Volatile pair, slow chain, or a large amount? Fixed rate. Paying a small premium to remove settlement risk is usually the right call when the exposure window is long.
- Stable pair, fast chain, small amount? Floating rate. The window is short, the risk is small, and you keep the better rate.
Minimums and maximums
Every exchanger order has a minimum and a maximum size, and they're per-provider, not universal. Fall outside them and the order is rejected — or worse, accepted and then dropped into a refund flow, which costs you time and two network fees for nothing.
If a quote looks impossible, an out-of-range amount is the first thing to suspect.
Reading a quote in five seconds
- What lands? Find the output amount. That's your real price.
- What does my send cost? Add the network fee for the chain you're sending from. It's not in the quote.
- Fixed or floating? Match it to how volatile the pair is and how slow the chain is.
- Am I inside the limits? Check the minimum and maximum.
- Is a different provider better? The aggregator is showing you competing offers. Look at more than the first one.
The uncomfortable truth about small trades
Fixed costs — the destination network fee, your own send fee — don't shrink when your trade does. On a $20 swap into an Ethereum-mainnet asset, they can eat a serious fraction of the value. On a $2,000 swap, they're a rounding error.
There's no clever fix for this, only an honest observation: small swaps on expensive chains are a bad deal, and no aggregator can make them a good one. If you're moving small amounts, do it on a cheap chain, or batch it into fewer, larger trades. That single decision will save you more than any amount of provider-shopping.
For where these costs come from architecturally, see Swapping Tokens Inside SSP vs Using a DEX. For the buy and sell sides, see Buying Crypto Inside SSP and Selling Crypto from SSP.
