"I set a stop-loss at a $10 loss, but why do I lose more money when the exchange triggers the stop-loss? And when I take profit, why do I receive less money?"

In reality, the figures on the exchange’s calculator are only provisional estimates. The formula is as follows:

Long profit = (Closing price - Opening price) * Position size
Short profit = (Opening price - Closing price) * Position size

Since this formula does not account for fees such as trading fees, funding fees, or liquidation fees, discrepancies arise. Additionally, most exchanges do not intervene in liquidity provision but allow market makers to trade freely. Therefore, if there is a liquidity shortage when your order is executed, it may match at a less favorable price, causing you to incur a slightly larger loss.

For example, if you want to quickly close a Long BTC position at $90,000, there must be someone willing to go Long at that price. However, if the only matching order available is at $89,995, you will incur an additional loss of $5 due to this price difference.