If you have ever opened a carry-on on a hotel floor and wondered how everything fitted inside it the day before, you have already dealt with a small-space design problem.
There is a fixed shell. Shoes compete with clothing. A laptop needs protection but also quick access. Toiletries should stay away from fabrics. Chargers disappear into corners. Dirty clothing eventually has to share the same limited space with clean clothing.
It is surprisingly close to designing a very small apartment.
There is an envelope that cannot easily expand. Different functions need their own zones. Frequently used objects should remain accessible. Awkward corners need to earn their space. And squeezing something into every available centimetre does not necessarily make the interior work better.
That comparison is becoming more relevant as travellers rely more heavily on cabin luggage.
Expedia’s 2026 Air Hacks research found that 48% of U.S. travellers now fly carry-on only. The trend is even creating new forms of travel: Expedia reports that one in four U.S. Millennial and Gen Z travellers plans to take a 24-hour international trip in 2026, often with little more than cabin luggage.
When the suitcase is expected to hold an entire trip, interior planning starts to matter.
The Exterior Is a Hard Boundary
Architects start with the site boundary.
Luggage designers have an even less forgiving one.
IATA says many airlines use 56 × 45 × 25 cm (22 × 18 × 10 in) as a general maximum reference for carry-on baggage, including wheels and handles. Some airlines also impose weight limits starting at just 5 kg (11 lb).
Actual allowances remain airline-specific.
This means every wheel, hinge, handle, divider and piece of hardware competes with the traveller for the same limited envelope.
Making the suitcase slightly larger can create more internal space, but it may also make the bag unacceptable on another airline.
The design problem is therefore familiar to anyone who works with small interiors: get more practical use from the space already available.
A Suitcase Works Better When It Has Zones
Imagine a studio apartment where the shower, stove, bed and front door all occupy one undivided room.
Technically, everything fits.
Living there would still be awkward.
A suitcase has the same problem when the interior is treated as one large box.
Shoes do not behave like shirts. Toiletries can leak. Electronics need protection. A jacket may not be needed until dinner, while a laptop could be required twice before boarding.
Thinking in zones makes more sense:
- Transit zone: laptop, chargers or items required while travelling
- Main zone: clothing and larger belongings
- Protected zone: electronics and fragile objects
- Separated zone: shoes, laundry or damp items
- Small-item zone: cables, toiletries and accessories
This is basic spatial planning at a much smaller scale.
Related functions stay together. Things that can interfere with one another are separated.
Access Matters as Much as Capacity
Airport security is a good test of suitcase design.
If the laptop technically fits but retrieving it requires opening the main compartment, moving a packing cube and lifting out two layers of clothing, the storage problem has not really been solved.
Architects think about circulation for the same reason.
A building can contain every required room and still be frustrating if reaching them means constantly crossing other spaces.
Modern luggage is increasingly separating items needed in transit from those needed only after arrival.
NOBL’s Duo Carry, for example, uses a detachable, lockable side bag alongside the main case. It includes a padded laptop sleeve, organised storage and a separate ventilated area for shoes or gear.
The design idea is more interesting than the individual feature list.
The part of the luggage needed during movement can operate independently from the part carrying most of the trip.
A similar principle appears in apartments with entry storage, service zones or rooms that can be divided as needs change.
Shoes Are Tiny Pieces of Wasted Architecture
Shoes are one of the stranger objects in a suitcase.
They occupy considerable volume, but much of that volume is hollow.
Anyone interested in small-space design should immediately see the problem.
An empty shoe inside a packed suitcase is essentially unused storage.
Filling shoes with socks, belts or small accessories recovers some of that space while also helping the shoes retain their shape. Keeping heavier footwear toward the wheel end can also improve weight distribution.
There are several practical ways to pack shoes in a suitcase, including wrapping the soles, filling the interior and positioning pairs around other belongings.
The larger lesson is useful beyond footwear.
Hats, bags and other hollow objects should not automatically be treated as solid blocks.
Good packing often starts by noticing where the empty volume actually is.
Compression Is Useful Until It Becomes the Problem
Compression has become one of the standard answers to limited suitcase space.
It works particularly well with clothing because fabric contains plenty of air.
But compression cannot change weight.
That matters when some airlines apply cabin-bag limits starting at 5 kg.
It also does very little for shoes, chargers, cosmetics or rigid objects. Delicate clothing can crease when packed under too much pressure, and an expandable case may become too deep for an airline’s cabin allowance once fully opened.
This is where the comparison with compact architecture becomes especially useful.
Small homes are rarely comfortable because every square centimetre has been filled.
They work because storage is deliberate and enough free space remains for the room to function.
The same principle applies inside luggage.
A suitcase packed to absolute capacity at home also leaves nowhere for a jacket removed at the airport, something purchased during the trip or clothing that never folds quite as neatly on the return journey.
The Best Small Spaces Can Change Function
One reason tiny apartments are interesting to architects is that one space often has to do several jobs.
A dining table folds into a wall.
A bed becomes storage.
A sliding partition changes one room into two.
Travel creates similar changes in use.
At the airport, a traveller may need a laptop and passport.
After arrival, they may want only a small day bag.
At the hotel, the entire case becomes storage.
On the return journey, the interior may need to accommodate purchases that were not there before.
That makes modularity particularly relevant to luggage.
Removable organisers and detachable compartments allow the same physical object to behave differently throughout the journey rather than forcing one fixed layout onto every situation.
That is a more useful form of flexibility than simply adding another pocket.
Technology Should Not Dictate the Life of the Suitcase
There is another mismatch product designers need to consider.
A good suitcase may last for years.
A battery, tracker or charging device probably will not.
Early smart luggage often treated those products as one system, integrating electronic components directly into the case.
Airline safety rules make that increasingly awkward.
IATA states that power banks and spare lithium batteries must remain in carry-on baggage, while FAA guidance similarly requires removable batteries in many types of battery-equipped luggage before the bag can travel in the hold.
A more durable approach separates the life cycles.
The suitcase provides a place or connection for technology.
The technology remains replaceable.
A removable power bank can be changed when battery performance declines. A tracker can be replaced when the standard changes. A phone provides the interface instead of forcing another screen into the luggage.
That is not very different from designing a building so its services can be repaired without demolishing the structure around them.
Even a Tracker Needs a Logical Place
Baggage tracking sounds like a technology issue, but there is a spatial-design question hidden inside it too.
Where should the tracker go?
It needs to be secure, difficult to lose and reasonably easy to access when its battery needs replacing.
Demand for that visibility is high.
IATA reported in 2026 that 81% of passengers want better baggage tracking and 88% expect real-time baggage updates on their phones.
There is a reason for that.
SITA’s latest Baggage IT Insights report says 24 million bags were mishandled globally in 2025. That sounds enormous, although the industry’s mishandling rate actually improved by 23% in a single year.
Tracking therefore sits at an interesting intersection between digital infrastructure and physical product design.
The suitcase does not necessarily need to become an electronic device.
Sometimes it simply needs to provide the electronic device with the right place to live.
Weight Distribution Changes How the Object Moves
Unlike most interiors, a suitcase spends much of its life moving.
That makes the position of objects matter outside the case as well as inside it.
Put several heavy items near the top and the luggage becomes easier to tip.
Allow dense objects to shift and the balance changes every time the case turns.
Place too much weight on one side and even good spinner wheels have more work to do.
The practical response is simple: heavier items generally belong lower and closer to the wheel end, with enough compression or restraint to stop them moving.
This is familiar territory for architects and engineers.
Mass is not only about how much there is.
Where it sits affects how the larger object behaves.
Repairability Is Part of Good Spatial Design Too
A wheel can fail while the shell remains almost perfect.
A handle can wear out before the interior lining.
A charging connection can become outdated long before the case itself reaches the end of its useful life.
That creates the same question architects face when thinking about a building’s service life: which parts will fail first, and can they be reached when they do?
Designing high-wear components so they can be repaired or replaced can extend the useful life of luggage considerably.
The argument becomes even stronger as more mechanisms are added.
A clever feature has limited value if its failure turns an otherwise usable suitcase into waste.
The Carry-On Is a Tiny Space With a Difficult Job
There is a lot being asked of roughly 56 × 45 × 25 centimetres.
The space has to carry clothing, technology, shoes and toiletries. It may have to meet a weight restriction. The contents need to survive movement while remaining organised. Certain objects need immediate access. Others need protection or separation.
Then the entire interior has to work again in reverse a few days later.
The rise of carry-on-only and even 24-hour international travel makes those decisions more noticeable.
Thinking of luggage as micro-architecture offers a useful way to approach them.
Where should the high-traffic objects live?
Which functions should be separated?
Where is empty volume being wasted?
What needs to adapt during the journey?
Which parts will wear first?
And can someone reach what they need without dismantling everything around it?
Those questions would be familiar in an architecture studio.
They happen to work surprisingly well for the smallest interior many of us travel with.
