What size duffel bag do I need for a weekend trip?

For a 2–3 day trip, most reviewers across the threads we read recommend something in the 30–50L range. A 30L bag like the Patagonia Black Hole Mini MLC fits airline personal-item or carry-on limits, while a 50L waxed canvas weekender gives more room for shoes and toiletries but starts pushing carry-on dimensions when fully packed.