# How do you start one-bag travel?

> OneBag Kit · https://onebagkit.com/how-to-start-one-bag-travel/  
> Updated: 2026-10-08 · Published: 2026-10-08

Take a two- or three-night trip with a bag you already own before you buy one. Pack it a week ahead, check it against your fare's size limit, and on the way home list what you never used. Then buy a 30–45 L travel pack sized to what's left. The cost is a less comfortable first trip. If nothing you own fits the cabin limit, buy first, from a shop that takes returns.

Five steps, in this order, because each one tells you something the next one needs:

1. Test-pack a bag you own and check it against your fare.
2. Take it on a trip of two or three nights.
3. Cut the list using what you didn't touch ([how to stop overpacking](https://onebagkit.com/how-to-stop-overpacking/index.md) has the test for borderline items).
4. Practise one wash ([the laundry guide](https://onebagkit.com/how-to-do-laundry-one-bag-travel/index.md) has the method).
5. Buy the bag, or keep the one you have ([how to choose a carry-on travel backpack](https://onebagkit.com/how-to-choose-a-carry-on-travel-backpack/index.md) covers fit).

## Test-pack a bag you already own

![An everyday backpack on a bathroom scale beside a tape measure, with a folded T-shirt that still has a small coloured tape tag on it.](https://onebagkit.com/img/brick-spot-how-to-start-one-bag-travel-640.webp)

Any soft backpack or duffel will do for a trial: a school pack, a gym bag, the bag you take to work. A poster in an [r/onebag thread reflecting on several trips](https://www.reddit.com/r/onebag/comments/1tzt4j7/reflecting_on_minimal_travel_after_some_onebag/) put it this way: "I would try to avoid buying basically any new stuff 'for travel.'" The exceptions they gave were a travel power converter or a battery pack, and trips of several months, though the same post calls a travel pack with "the proper load transferring harness" "basically always worth it", which is the bag to buy once a trial shows the size ([isaac-get-the-golem](https://www.reddit.com/r/onebag/comments/1tzt4j7/reflecting_on_minimal_travel_after_some_onebag/)).

Pack it a week before you leave, with everything in it, then hold it up against the fare you booked. Ryanair includes one small bag of 40 × 30 × 20 cm on every fare, kept under the seat, and its Priority option adds a 10 kg bag of 55 × 40 × 20 cm for the overhead locker ([Ryanair bag rules](https://help.ryanair.com/hc/en-gb/categories/12489112419089-Bag-Rules), checked 8 Oct 2026). Lufthansa's personal item is smaller, 40 × 30 × 15 cm, and its carry-on is 8 kg at 55 × 40 × 23 cm, though an Economy Basic ticket on short- or medium-haul routes comes with the personal item alone ([Lufthansa carry-on baggage](https://www.lufthansa.com/us/en/carry-on-baggage), checked 8 Oct 2026). [How to measure a carry-on bag](https://onebagkit.com/how-to-measure-a-carry-on-bag/index.md) shows where to put the tape. Weigh the bag too, and write both numbers down. You'll want them after the trip.

## A first trip: three nights in Gothenburg

A first-timer posted their whole list in r/onebag before [three nights in Gothenburg in early October](https://www.reddit.com/r/onebag/comments/1wrmo8d/3_nights_in_gothenburg_early_oct_first_time/). The bag was an American Tourister Take2cabin S/M backpack listed at 40 × 30 × 20 cm and 26.5 L, booked on Ryanair's basic fare. Packed, it weighed 4.5 kg and was within the permitted dimensions by the poster's own measure, though the post still hoped it would fit "the Ryanair sizer". The poster called it "a trial run for a longer trip to Copenhagen", a week at the end of October ([comment](https://www.reddit.com/r/onebag/comments/1wrmo8d/3_nights_in_gothenburg_early_oct_first_time/pcdpoi7/)), and planned to "test this on a short trip first and then essentially take the same stuff for longer and longer trips" ([comment](https://www.reddit.com/r/onebag/comments/1wrmo8d/3_nights_in_gothenburg_early_oct_first_time/pcexhlb/)).

Run the numbers on that bag. It matches Ryanair's free small bag to the centimetre, with nothing spare on any side. A commenter in the same thread warned that Ryanair "has used open frame sizers in Gothenburg. No squishing" ([SeattleHikeBike](https://www.reddit.com/r/onebag/comments/1wrmo8d/3_nights_in_gothenburg_early_oct_first_time/pci0abc/)), so a bag that matches on paper but bulges when packed can still fail. On a Lufthansa Economy Basic ticket the same bag is 5 cm too deep (20 cm against 15 cm). A trial proves the bag for the airline it was flown on and no other. At 26.5 L it is also below the 30–45 L range we suggest for a first bought pack, which makes it a fair test: if a week fits in 26.5 L, a 40 L bag leaves room to spare.

The poster said they were "kinda deliberately over packing a little" and not washing anything, to prove the setup before the longer trip ([comment](https://www.reddit.com/r/onebag/comments/1wrmo8d/3_nights_in_gothenburg_early_oct_first_time/pcewpro/)). The bag still bulged and sagged a bit while not full. Replies split two ways. One commenter said to take the list as it is, then "When you get back, mindfully re-evaluate what you DID NOT use or wear" ([zdubbzzz](https://www.reddit.com/r/onebag/comments/1wrmo8d/3_nights_in_gothenburg_early_oct_first_time/pcevlle/)). Others pushed for a much shorter list, and the poster answered that "There's a difference between optimising the contents and minimising the contents of a bag" ([comment](https://www.reddit.com/r/onebag/comments/1wrmo8d/3_nights_in_gothenburg_early_oct_first_time/pcy9lm2/)). We side with the first reply for a first trip. Pack what feels safe, take it, and make the cuts from what came back unused.

## Cutting the list after the trip

Start the cut list on the way home, while you still remember what stayed packed. One r/onebag commenter marks each item before packing: "Attach a small piece of colored tape to each thing you pack and remove the tape when you use an item" ([squeebs555](https://www.reddit.com/r/onebag/comments/1uksf8r/i_packed_for_a_5day_trip_with_one_bag_and/ov0dw66/)). Whatever still has tape on it at home goes on the cut list.

Don't cut everything that came back unused. In the same thread, a commenter pointed out that a rain jacket or a small sewing kit can stay in the bag untouched on one trip and still matter on the next, and that a few trips in different conditions "usually sorts it out" ([LadyLightTravel](https://www.reddit.com/r/onebag/comments/1uksf8r/i_packed_for_a_5day_trip_with_one_bag_and/ouz2ejd/)). For the items you're unsure about, the three questions on [how to stop overpacking](https://onebagkit.com/how-to-stop-overpacking/index.md) settle most of them.

Weight is the other thing a trial shows you. A first-timer took a Patagonia MLC 45L to eastern Europe for six days with six T-shirts and a 13-inch laptop, and wrote while boarding that the "bag felt pretty heavy on the shoulders"; a bulge also made it hard to fit in the overhead bin ([Different_Scholar548](https://www.reddit.com/r/onebag/comments/1rqp433/first_time_onebag_trip_mlc_45l/o9wn3in/)). They planned to pack lighter next time. For a printed starting point, the [free checklist](https://onebagkit.com/checklist/index.md) has every group to tick off.

## Practise one wash before a longer trip

A short trip doesn't need laundry. A week or more in one bag does, and washing is easier to learn at home than in a small hotel room. In the Gothenburg thread, a commenter told the poster that if they weren't washing on their trips, "I would strongly recommend you learn sink washing at home" ([LadyLightTravel](https://www.reddit.com/r/onebag/comments/1wrmo8d/3_nights_in_gothenburg_early_oct_first_time/pch4ybj/)). The poster already planned to wash every three or four days on longer trips so things have time to dry ([comment](https://www.reddit.com/r/onebag/comments/1wrmo8d/3_nights_in_gothenburg_early_oct_first_time/pcixisa/)).

The test that helps most is drying time. A commenter on an r/onebag tips thread suggested a test hand wash at home, because "Some things are much easier to wash and dry than others", and noted, "I've got some T-shirts that dry overnight and some that take DAYS" ([Responsible-Walrus-5](https://www.reddit.com/r/onebag/comments/1osy9vi/after_scrolling_through_the_community_for_a_long/no0xojo/)). Wash the shirts from your trial in a bathroom sink one evening and check them in the morning. The ones still damp are the ones to replace first, before you spend anything on a bag. [How to do laundry on a one-bag trip](https://onebagkit.com/how-to-do-laundry-one-bag-travel/index.md) has the sink method and the kit.

## Buy the bag, or keep the one you have

If the trial bag held everything with room left and didn't hurt to carry, keep it. If it didn't, you now know the volume you need. A first-timer who was "worried the 30L would be too small" and found that "the next size up (45L) felt huge" took a Patagonia 30L MLC mini on 13 days in Spain and Portugal, and wrote that it "ended up being perfect" ([errboww](https://www.reddit.com/r/onebag/comments/1tnkbx7/my_first_one_bag_trip_patagonia_30l_mlc_mini/)). Afterwards they said they would "pack less and plan to do laundry mid trip" next time ([errboww](https://www.reddit.com/r/onebag/comments/1tnkbx7/my_first_one_bag_trip_patagonia_30l_mlc_mini/oo2p3jv/)).

Buy within 30–45 L, at the size your trial list fills, and check its depth against the fares you fly. Three packing cubes (two medium, one small) and a laptop fit a 40 L pack, as the worked example on [is a 40L backpack big enough](https://onebagkit.com/is-a-40l-backpack-big-enough/index.md) shows. The empty bag counts against a weight cap: Lufthansa allows 8 kg in the cabin, and Singapore Airlines 7 kg in Economy ([Singapore Airlines cabin baggage](https://www.singaporeair.com/en_UK/sg/travel-info/baggage/cabin-baggage/), checked 8 Oct 2026). [How to choose a carry-on travel backpack](https://onebagkit.com/how-to-choose-a-carry-on-travel-backpack/index.md) covers harness fit and empty weight.

## When to wait before going one-bag

Some first trips are a poor place to start. If the trial list already includes a suit for a wedding, ski or camping kit, or two climates, check a bag this time and run the trial on a simpler weekend; [the main one-bag guide](https://onebagkit.com/carry-on-one-bag-packing/index.md) lists the trips that outgrow a carry-on. An under-seat-only fare suits a short first trip like the Gothenburg one, but not a first week away, and Lufthansa's Economy Basic bag, at 40 × 30 × 15 cm, is 5 cm shallower than Ryanair's free one. A week in an under-seat bag is a harder exercise than one 40 L bag, covered in [how to pack with only a personal item](https://onebagkit.com/personal-item-only-packing/index.md). For a longer first trip, book a fare that includes a full-size cabin bag, and move to the smaller allowance once you know what you use.

## Related OneBag Kit guides

- [How to stop overpacking “just in case” items](https://onebagkit.com/how-to-stop-overpacking/index.md): three questions to put to whatever your trial trip left unused
- [How to do laundry on a one-bag trip](https://onebagkit.com/how-to-do-laundry-one-bag-travel/index.md): sink washing, drying overnight and the kit for a longer trip
- [How to choose a carry-on travel backpack (deep guide)](https://onebagkit.com/how-to-choose-a-carry-on-travel-backpack/index.md): fit, empty weight and pockets once you know the volume
- [How to pack carry-on / one bag](https://onebagkit.com/carry-on-one-bag-packing/index.md): a full ten-day trip in one 40 L bag, once the trial is done

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