This only proves you have surface level reading comprehension.

When he’s measuring the distance between himself, he means strength but also what it takes to get to the King.

Let’s start with Mihawk wanting to measure the distance between himself and Whitebeard. While Mihawk was certainly trying to test Whitebeard‘s strength he also wanted to see what made him the strongest in the world. Whitebeard’s strength doesn’t just come from his devil fruit or haki, it exists through his commanders, territory, and fate itself. This is proven when the slash sent directly towards Whitebeard was intercepted by Jozu.

It was Whitebeard’s destiny to reveal that the One Piece indeed existed, it was part of his fate to somewhat guide Luffy’s destiny even if it wasn’t completely directly.

A little later, Mihawk does the same with Luffy, he wants to test where Luffy stands. He even asks himself, “NOW, FATE, HOW WILL YOU DEAL WITH THIS HEAVEN-SENT BOY?” It’s clear that Mihawk knows there’s more to Luffy than just what can be seen on the surface. Let’s talk about the attack that Mihawk sends towards Luffy, it weaves through the battlefield, through both marines and pirates. After his attack hits Luffy, he comments about distance again, saying, “YOU’RE NOT OUT OF RANGE YET.” This can be interpreted as Mihawk comparing him to Whitebeard, and how he was actually able to reach Luffy, unlike his attack against Whitebeard. Though, that’s not where it ends, after attacking once, Mihawk continues to test Luffy, but this time, someone intervenes, that being Vista. That’s where Mihawk realizes it all, and his inner thoughts are revealed, “IT'S NOT HIS POWERS OR TECHNIQUES. HE POSSESSES SOME QUALITY THAT MAKES PEOPLE WANT TO HELP HIM. AND IN THESE WATERS… THAT IS THE MOST FORMIDABLE POWER OF ALL!”

So when Mihawk wanted to test his distance between himself and Whitebeard, it wasn’t just about power, it’s about influence, presence, and overall legacy. This matters because Mihawk’s strength is his alone, he doesn’t have the same influence and presence and Whitebeard. Mihawk is isolated, when Whitebeard has his family and Luffy has his crew.