I'm a long-time player with a small handful of DMing experiences. I'm getting a group of coworkers together to play a one-shot or two via Discord (we all work remotely and don't get to see each other often but are fairly close) but most aren't very experienced (one has never played). I've got a ton of official content a quite a lot of Kobold Press one-shots to dig through, but everything seems tailored for parties of 3-5 PCs. It's looking like we're going to have 7-8 in this group... I'm very aware that this is a huge adventuring party but I'm not sure the best way to adjust difficulty. I don't want to throw them into an adventure for higher level PCs as they could probably get wiped out quickly, despite their numbers. I've never had much luck trying to use the formulas for CR & XR. Is there another relatively easy way to adjust some of these encounters for more low-level PCs? Just add more gerblins?

For the most part, you can just multiply encounter size by relative party size (or mix things up by combining encounters; just taking two encounters and combining them is fair). This will somewhat break down when dealing with monsters with area effects -- the CR calculation generally assumes area effects hitting two targets, and more PCs means more PCs being hit.

For encounter building, the rules in Xanathar's are somewhat easier to use, though they do generate roughly medium encounters.

Understood, and more or less what I expected. I know we'll struggle with pace, but this is a pretty close group of type-As. I just don't want encounters to be super easy because of the number of players and, obviously, don't want to bump up difficulty to the point where they get stomped.

I've played around with the Xanathar's rules a bit but I'll dig in deeper and see what I come up with. Thank you for the response!