The short answer: measure the object once it's already protected
The right box is the smallest one in which the product fits wrapped, separated from the walls, and unable to move. Don't choose the size using only the bare object: a sleeve, several layers of foam, accessories, and filler also take up space.
As a guide, a mobile phone might start in a 16x10x5 cm box, a single book in 28x23x5 cm, a folded garment in 30x20x10 cm, shoes around 34.5x21x12.5 cm, and a protected laptop in a 42x30x14 cm box or larger. These are starting points, not universal measurements: always check the useful internal space of the box and remeasure the item after protecting it.
Quick size chart by object
| Object | Suggested box | Recommended protection | Key check |
|---|---|---|---|
| Small mobile phone | From 16x10x5 cm | Foam sleeve and perimeter filling | Must not touch any wall |
| Single book | 28x23x5 cm | Edge and corner protection | Cover should not slide |
| T-shirt or thin garment | 30x20x10 cm | Inner bag against moisture | Do not compress until deformed |
| Shoes without original box | 34.5x21x12.5 cm | Paper inside and between both shoes | Size and model may require more |
| Compact laptop | From 42x30x14 cm | Foam on all sides and corners | Also measure charger and accessories |
| Console | 40x29x25 or 50x35x35 cm | Wrap console, controllers, and cables separately | No part should collide with another |
These measurements help narrow down the search. In small and medium boxes you'll find formats for books, clothing, and compact items; for larger equipment, compare the collection of shipping boxes.
The formula for choosing a box without mistakes
Use this relationship for each dimension:
Useful internal box measurement ≥ measurement of the product already protected
Before comparing numbers, distinguish length, width, and height and check if the product sheet publishes internal or external measurements. The previous guide on how to measure a cardboard box explains the correct order and avoids swapping dimensions.
- Place the object as it will travel: folded, disassembled, or with its accessories grouped.
- Wrap surfaces and specifically protect corners, screens, and protruding parts.
- Remarry length, width, and height at the point of greatest volume.
- Choose a box whose interior accommodates those three measurements without forcing the closure.
- Fill the remaining space and perform a movement test before sealing.
There is no fixed margin valid for any product. A t-shirt may need very little extra space; a screen, a ceramic piece, or heavy equipment needs a continuous buffer zone. The goal is not to fill the box with filler, but to prevent impact from reaching the item.
Small objects: mobile, cosmetics, and accessories
For a mobile phone or a compact accessory, a 16x10x5 cm postal box can be a good starting point if the already protected device fits without pressure. Inserting it naked because the measurement seems exact is a mistake: the screen and corners would be too close to the outside.
Group cables and small parts in a separate bag, never loose on the screen. If there are liquids or cosmetics, close each container, add a watertight barrier, and keep them separate from the cardboard. When several items share a box, wrap each unit so they can't hit each other.
Books: snug, but without damaging the corners
A book sleeve of 28x23x5 cm reduces empty space and protects better than a deep box. If the book has a dust jacket, delicate corners, or collector's value, add a protective sheet and flat cardboard to both covers before closing.
For multiple books, distribute the weight. A huge box filled to the brim can exceed manageable weight and break at the bottom. Place the books flat, eliminate lateral movement, and reinforce the bottom closure with packing tape.
Clothing: the size depends on how you fold it
Fold the garment before measuring it and place it in a clean bag to protect it from moisture and dust. A 30x20x10 cm box usually accommodates one or more thin garments; a jacket, a handbag, or a bulky lot will need more height.
Don't force a box to reduce a few centimeters. If the cardboard bulges, the flaps don't close flat, and the package loses strength. Nor should you leave a small garment in a disproportionate box: you'll occupy shipping volume and waste filler without improving protection.
Shoes: measure the pair, not a single unit
Place paper inside to retain shape, protect each shoe, and measure the set. A 34.5x21x12.5 cm postal box may work for certain pairs without original packaging, but the size, heel, and type of footwear greatly change the volume.
If you keep the brand's box, use it as inner presentation and add an outer box. The original box should not travel exposed to rain, labels, scuffs, and bumps if it is part of the product's value.
Laptops and consoles: protection rules, not nominal measurement
For electronics, measure the device after wrapping it on all sides. A 42x30x14 cm postal box may fit some compact laptops; ensure there is real margin for foam on the base, lid, sides, and corners. If the equipment is heavy or the journey demanding, consider a more resistant cardboard box.
For a console, a 40x29x25 cm flap box may be sufficient depending on the model and its accessories. Separate controllers, power supply, base, and cables. A loose part can become the impact that damages the casing during transport.
The four mistakes that waste the most space and money
- Using outer measurements as if they were inner: the thickness of the cardboard and the folds reduce useful space.
- Measuring the object without protection: then it doesn't fit or padding is removed to close it.
- Choosing a huge box "for safety": increases filler, volume, and internal movement.
- Ignoring weight: a box that fits by volume may not have the necessary strength for the load.
Before buying several units, prepare a complete sample and check dimensions, weight, closure, and handling. This test avoids adopting a box that works on the table but fails when the order includes accessories or a different size.
If the object is heavy, don't decide only by volume: consult how much weight a cardboard box can hold and adapt the channel's resistance to the load and the journey.
Related guides to finalize the shipment
If the sale comes from a second-hand platform, review the specific rules for packaging for Wallapop and Vinted. To convert the chosen box into a cost per order, use the ecommerce packaging cost formula. And before delivering delicate products, go through the checklist to reduce damage and claims.
Frequently asked questions
How many centimeters should I add to the object?
There is no universal figure. Add the actual thickness of the necessary protection on each side and measure afterward. A flexible product needs less margin than a fragile or electronic piece.
Are box measurements internal or external?
It depends on how the manufacturer or store publishes them. Check the product sheet and look for the useful internal measurement before confirming that your protected item fits.
Is it better to have extra space?
Only what's necessary for cushioning. Empty space without filling allows movement; an excessive box consumes more material and can increase volumetric transport costs.
Can I use the original box of a laptop or a console?
Yes, as inner packaging if it retains its protections. For shipping, it is advisable to put it inside a fitted outer box that protects the original packaging and conceals the content.
How do I know if the box is well-fitted?
It should close flat, without bulging or compressing the item. After filling the gaps, the contents should not move when gently tilting or shaking the package.
In summary
Protect first, then measure. Compare the three dimensions with the useful interior of the box, check the weight, and choose the smallest format that keeps the product separated from the walls and completely immobile. This reduces filler, transport volume, and damage without trying to save space at the expense of protection.
