Prevent items in suitcase from shifting around

Thank you for this idea to use cardboard boxes to fill empty space so things don't shift around!

We too, often have this challenge with our nesting luggage set. The largest suitcase simply becomes TOO heavy if filled completely. Yet at our destination we like to unpack and nest all three (carryon, 26" and 29") together to save space. I found a cardboard box that is 14x10x5 inches which I believe will occupy enough space to prevent our largest suitcase to exceed weight AND prevent items from moving around AND prevent the top of the suitcase to sag and which causes it to be excessively beaten up by baggage handling.

As books are heavy I would wrap them together tightly with clear wrap, which would also protect them, and place them at the bottom of the suitcase. Fill the middle of the suitcase with your clothing and other items in packing cubes, heaviest items towards the bottom I find works best. Finally use sturdy cardboard boxes to fill any empty space remaining near the top.

I love rolling my clothes! You can get your clothing into the nooks and crannies created by the suitcase and books. The suitcase is most likely to be handled in the standing/rolling position so I typically lay the heaviest items at the bottom of the suitcase. When gravity takes place, the heavy items won't squish all my clothing/toiletries.

Pack travel friendly clothing/wrinkle spray

My other suggestion is packing travel friendly clothing (synthetic materials). Anti-wrinkle or wrinkle resistant travel clothes are a life saver. Using fabric softeners should also help prevent extreme wrinkling beforehand.

If you can't forego cottons and other materials that wrinkle easily (cotton, rayon, linen) then look into some wrinkle relaxing spray. The gist is to hang and spray the clothing. Then after a few minutes, the wrinkles should relax. Another trick is allowing the clothing to hang in the bathroom while you take a hot steamy shower. There are other DIY and tricks on how to make your own spray but at your own risk!

Compression bags

Look into travel clothing bags to preserve your best clothing. These should be secured flat on top of everything else. Some suitcases have those elastic bands inside for this purpose. Sometimes I use compression bags to keep clothing flat.

These won't replace having to iron your clothes but if you can pack effectively, you'll be able to prevent the worst. Some hotels, hostels, or air bnbs may offer irons as part of their service if you inquire ahead of time.

Travel clothing and compression bags can be found at travel stores like Tilly, Columbia, Mountain Equipment Coop, Travel Smith, etc...

Obviously a fuller and more densely packed suitcase helps item stay in place. So, go ahead and pack more stuff or use a smaller suitcase, although it nice to have room to bring things back.

What happens though is that items of different densities will cause others to compress. This happens while carrying books for example. Packing them towards the bottom of the suitcase helps but is not a complete solution. One thing that I do particularly with books is wrap them with rubber bands to keep them from opening and get more mixed and damaged by other items.

The most effective though is to use packing cubes and compression bags. Clothes that do not wrinkle easily go into compression bags which makes them dense and tight, so they resist better pressure of other items. Cubes keep the rest organized and really minimize shifting more than anything else. You basically put everything that fits into the cubes and put the filled compression bags around which takes care of neatly immobilizing most items.

If your suitcase is flexible and still have some room to expand, you can add a compression strap. All these products are available from travel stores on online at Amazon and are not very costly but once you start using them, can make unpacking much more pleasant.

If you need the space in the suitcase only one way, you could fill the case on the other leg with cheap and light items.

When packaging for work we use air filled plastic bags, filled and sealed by a machine. I do not know how well those travel by air, with different pressures and such.
But an alternative is bubble wrap and scrunched up paper possibly in zip-lock bags with some air in it as well as the paper.
Or card board boxes which are sturdy enough to keep your things sorted around them.

With those you can fill your case so there is no 'empty space'.

The most obvious answer would be to fully fill your suitcase (by putting more things into your existing suitcase, or by using a smaller suitcase where everything fit snugly). Of course, you'll have to be careful to avoid overloading the bag and exceeding airline weight limits, assuming you fly.

You can also pack smaller objects together, e.g. you could make a stack of books and then bag them, wrapping the bag securely around them, to keep them from sliding around so much. (Either the whole pile will shift, or none of them will shift, if you pack them correctly.)

One other secret with clothing is to roll it, not fold it. Rolled clothing seems to survive shifting contents better.