Two weeks does not need twice what one week needs. Past roughly seven days, the size of your bag is decided by whether you will do laundry, not by how long you are away — and the difference between the two lists is smaller than most people expect.
Past roughly seven days, bag size stops tracking trip length and starts tracking one decision: whether you will do laundry. A fortnight with a single wash packs much like a week. A fortnight without one is a checked bag.
Both generated by the packing tool for the same warm-weather city trip, changing only the duration. The gap is smaller than the doubling of days suggests, because documents, tech and toiletries do not scale with time.
| 7 days, warm | 14 days, warm |
|---|---|
| 24 items | 24 items |
| ~13 L packed | ~15 L packed |
| 33 garments | 52 garments |
| Fits a carry-on | Fits a carry-on |
Prescription medication is the one thing to over-provide for, with enough margin to cover a delayed return. Everything else — toiletries, socks, a phone cable — can be bought almost anywhere and is not worth the packing volume.
Close to what you would pack for a week, plus one laundry stop. Packing fourteen distinct outfits is what turns a manageable bag into a checked one.
In warm weather, comfortably, provided you wash clothes once. In cold weather it is much harder, because the bulk per garment is what fills the bag.
Less than the length suggests. Documents, tech and toiletries are fixed costs that do not scale with time; only clothing grows, and laundry caps that.
Pick the midpoint and a place you will be for two nights. Hotel laundry is quick and expensive, laundrettes are cheap and cost an afternoon, and a sink handles underwear and shirts if you bring a travel detergent.
Slightly, but toiletries are the easiest thing to buy on arrival almost anywhere. Prescription medication is the exception and should cover the full trip with margin.