Why exchanges have minimum and maximum amounts

Every pair has a range. Send less than the minimum and the order cannot be filled; send more than the maximum and it has to be handled differently.

The minimum

Settling an exchange costs a network fee on each side. Below a certain size, those fees eat the whole amount. The minimum is roughly where the trade stops making sense, which is why it is higher on expensive chains and moves when fees move.

The maximum

A large order can be bigger than the liquidity available at the quoted price. Beyond that point it is filled differently rather than refused outright.

In practice

Swap Heaven shows the range for the pair you have chosen as part of the quote. If your amount is outside it, you will be told before you send rather than after. If you are near the minimum, remember that the quote assumes the amount actually arriving, so a wallet that deducts its fee from the amount sent can land you just under.