How much mark-room am I actually owed at the mark?
Mark-room is room for three things: to sail to the mark when that's your proper course, to round or pass it on the required side, and to leave it. There is no fixed maximum and no minimum — the space depends on the existing conditions: wind, sea state, your speed, your sails and your boat. Light air on a flat lake, barely a boat-length; a steep sea with the mark pitching, more than a hull-length. You're owed what you actually need to do it in a seamanlike way.
<iframe width="560" height="315" src="https://www.youtube.com/embed/AiLKmHfAYiE" title="Sailing Kiwi" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>
<p><a href="https://sailing.kiwi.nz/leeward-mark/rule-18-how-much-mark-room/">Source: Sailing Kiwi</a></p>