Pick any liquid pair and pull quotes from a dozen exchangers. The rates cluster tightly — usually inside half a percent — because they are all pricing off the same underlying market. Then compare what those services actually pay out on the same input amount, and the spread opens to several percent.
The difference is entirely in things the rate does not mention.
Network fee, deducted at payout
The largest and least visible component. An exchanger quotes you a rate, then deducts the cost of the outbound transaction from your payout. On a Tron payout that is a dollar and nobody notices. On an Ethereum payout during a busy hour it can be twenty, which on a $500 trade is four percent — larger than every other factor combined.
Some services publish the deduction, some fold it into a worse rate, and some do both. Where a partner reports it, we show it; where it is folded into the rate, ranking by payout catches it anyway.
The spread itself
The exchanger buys at one price and sells at another, and the gap is its margin. Typical is 0.5% to 2% depending on the pair’s liquidity and the service’s positioning. This is the honest, expected cost of the service.
It is also the part that competition compresses, which is why an aggregated table tends to produce better prices than any single service’s front page: the services that are visible in a comparison behave differently from those that are not.
Amount tiers
Many exchangers price in bands. The rate on the front page is often the one for a mid-sized trade, and both smaller and much larger amounts get worse treatment — smaller because fixed costs dominate, larger because the reserve has to be rebalanced.
This is why quoting at a realistic amount matters. A comparison run at one unit of the source asset tells you very little about what a $50 trade will do.
Reserve depth
A rate against a reserve smaller than your trade is not a price, it is an advertisement. What happens next is either a partial fill, a wait while the service rebalances, or a refund minus fees.
Reserve is the column people skip and the one that most often explains a transaction that “went wrong”.
Rate type
A fixed quote costs more than a floating one for the same pair, because the exchanger is absorbing price risk on your behalf. Comparing a fixed quote from one service against a floating quote from another and concluding that the first is expensive is a category error. Both appear in our table, marked, so the comparison is at least labelled.
Why we sort by payout
Every factor above is invisible in a rate and visible in an amount. Sorting the table by what actually lands in your wallet is not a design preference; it is the only ordering that cannot be gamed by moving cost from one column to another.
The rate is still shown, because it is a useful sanity check. It is just not what the ordering is based on.