×
Too tight
The product jams, packing slows down and the carton bulges. There is no room for inserts, tissue or a protective wrap.
Box measurement guide
How to measure a box correctly
Learn the simple L × W × H rule, understand internal versus external dimensions, and work out exactly what Pakko needs to manufacture packaging that fits your product.
Tap a dimension to see it on the box
Length — the longer dimension across the opening or base of the box. In 300 × 200 × 100mm, the length is 300mm.
Length
300mm
300mm
Width
200mm
200mm
Height
100mm
100mm
L × W × H · MILLIMETRES300 × 200 × 100mm
Australian packaging manufacturer
Brisbane based
ISO 9001 accredited
Structural design in-house
The simple rule
Length × Width × Height
Box measurements are written in one order, every time. 300 × 200 × 100mm means a length of 300mm, a width of 200mm and a height of 100mm. Select a card to highlight that dimension on the diagram above.
Remember this: always give dimensions in millimetres, in L × W × H order.
Internal vs external
Internal or external dimensions?
This is one of the most common packaging mistakes. There is an important difference between the space inside the box and the finished size outside the box — cardboard has thickness.
Internal dimensions
Internal dimensions describe the usable space available for your product. When developing custom packaging with Pakko, these are usually the most useful measurements because they tell us what needs to fit inside.
- What the product actually sits in
- The starting point for custom packaging
- Where inserts and protection are allowed for
- Normally what Pakko quotes from
The gap becomes more noticeable with heavier corrugated board, double-wall board or multi-layer packaging. Not sure which to send? Send both and label them clearly.
300 × 200 × 100mm
Board thicknessUsable internal space
Cross-section of a carton wall: mint line shows which measurement internal figure refers to.
Choose your path
What are you measuring?
Pick the situation that matches yours and we will show the right steps. Nothing is hidden — you can read every path.
Measure the box
Measure the inside of the assembled box
If you want an existing box reproduced, the internal cavity is what matters. Assemble the box first, then measure the usable space.
- 1Assemble the box exactly as it is used.
- 2Measure internal Length, Width and Height in millimetres.
- 3Note the approximate board thickness if you can.
!Always measure corner to corner. Board has some flex, so measuring across the middle of a panel can bow inwards or outwards and give you the wrong dimension.
Even better, send Pakko
- A photo of the box assembled
- A photo of the box opened or flattened
- The existing packaging sample
- The approximate board thickness
- Your annual or order quantity
- What product goes inside
Box style explorer
Choose your box style
Different constructions are measured differently. Find the closest structure to yours, then follow the three steps — and check what not to include.
Swipe for all seven box styles.
Reference photo
Shipping carton (RSC)
Regular Slotted Cartons are one of the most widely used transport boxes. Measure the internal cavity once the carton is assembled.
L
Longer opening dimension, measured inside the assembled carton.
W
Shorter opening dimension across the same opening.
H
Inside the base up to the top of the carton walls.
What not to measure
Closing flaps. They are part of the construction and are not added to the usable height.
Measure with the carton assembled — a flat blank will not give you the usable cavity.
Quote this styleAll seven box styles at a glance
Shipping carton / RSC
Measure: Inside L × W × H
Do not include: Closing flaps
Mailer box
Measure: Usable internal L × W × H
Do not include: Locking tabs, wings and external folds
Tuck end carton
Measure: Internal main-panel L × W × H
Do not include: Tuck flaps and dust flaps
Box + lid
Measure: Base internal L × W × H
Do not include: Lid allowance — do not guess it
Sleeve
Measure: Dimensions of the item the sleeve fits around
Do not include: Treating sleeve as a normal cavity box
Carry handle
Measure: Usable body L × W × H
Do not include: Handle above the main product area
Spare parts / industrial
Measure: Product maximum L × W × H plus protection
Do not include: Weight, sharp edges and handling requirements
Fit and clearance
How much space should I leave around my product?
There is no universal clearance. The right allowance depends on the product, protection, inserts, board material and packaging structure.
✓
Right-sized
Enough clearance for protection and easy removal, without transporting air. Pakko can engineer this fit around your product.
!
Too loose
The product moves in transit, more void fill is needed and the parcel takes more space in storage and freight.
A close-fitting retail carton
Cosmetics, pharmaceuticals, supplements and small retail products may require relatively precise dimensions. Packaging may also incorporate a custom insert to hold the product securely.
An ecommerce mailer
A mailer may need additional room for tissue, documentation or protective material while still keeping the contents secure during transport.
Fragile products
Fragile products may require more space for protective packaging or an engineered insert designed around the product.
Heavy products
Heavy products can require different board grades, box constructions and internal support — clearance is only part of the answer.
Multiple products
If several products are packed together, measure them in the exact configuration you intend to ship.
Irregular products
Measuring something that isn't rectangular
Imagine the smallest invisible rectangular box that can contain the entire product. Measure the maximum length, width and height to the furthest protruding points.
Select a protruding part to see what people commonly forget to include.
Handles and grips
A handle can push the bounding box wider or taller than the body of the product. Measure from the outermost edge of the handle, not the body.
Measure to outermost points — including handles, caps, wheels, knobs and fittings.
The complete pack
Measure everything the customer receives
One of the easiest mistakes is measuring only the hero product. Before deciding your finished box dimensions, arrange the full pack exactly as the customer will receive it.
Nothing selected yet
0 of 10 included
Start with the product, then add everything else that travels inside the finished box.
Volume calculator
Calculate your box volume
Enter length, width and height in millimetres to estimate internal volume. Volume is useful for comparing box sizes, but it doesn't determine board strength or suitability.
Proportions preview
L
W
H
Internal volume
6litres
0.006 m³
300 × 200 × 100 mm = 6,000,000 mm³
Freight providers may consider parcel dimensions as well as weight when calculating cubic or dimensional weight. Packaging should protect the product without transporting unnecessary air.
Quote-ready checklist
What Pakko needs to quote your packaging
Tick what you already have. You don't need every item to start — but the more you can tell us, the faster and more accurate the quote.
The essentials
Even better
- A photo of the product
- A photo of your current packaging
- An existing packaging sample
- A dieline or keyline
- The product itself
- Your expected annual volume
- Your packing method and freight requirements
You don't need to understand every technical packaging detail before contacting Pakko. That's part of what we're here to help with.
?
You do not need everything to contact us
If you know what the product is, roughly how big it is, what it weighs and how many you need, Pakko can help work through the rest.
Avoid these
8 box measuring mistakes to avoid
1Mistake
Giving dimensions in the wrong order
Use Length × Width × Height — not height × width × length.
2Mistake
Mixing internal and external measurements
Tell us clearly which you are providing. For custom product packaging, internal is normally the best starting point.
3Mistake
Forgetting accessories
Measure everything that needs to fit inside the finished package, not just the hero product.
4Mistake
Forgetting protective packaging
If an insert, wrap or divider sits between the product and box, it needs to be considered.
5Mistake
Measuring box flaps
Closing flaps are part of the construction and should not be added to your usable internal dimensions.
6Mistake
Rounding dimensions too much
Provide accurate measurements in millimetres. Small differences matter with close-fitting retail cartons.
7Mistake
Making the box unnecessarily large
More space is not always better. The objective is the right amount of space for the product.
8Mistake
Assuming board thickness does not matter
Different board grades have different thicknesses. Pakko accounts for this when converting internal dimensions into a manufacturable design.
FAQ
Questions about box measurements
Are box dimensions measured Length × Width × Height?
Yes. Packaging dimensions are commonly supplied as Length × Width × Height, written as L × W × H.
Are cardboard box dimensions internal or external?
Packaging manufacturers commonly work from internal dimensions when the objective is determining how much usable space is inside the box. However, external dimensions are also important for freight, storage, palletisation and other applications. Always state which measurement you are providing.
Does length always mean the longest side?
For many standard rectangular boxes, length will be the longer dimension of the opening or main panel. For specialised packaging constructions, panel orientation can sometimes affect terminology, so providing a photo or dieline can help avoid confusion.
Is height the same as depth?
The terms are sometimes used interchangeably in packaging. Pakko generally uses Length × Width × Height to keep specifications consistent.
Should I measure my product or my current box?
If you want an existing box reproduced, measure the internal dimensions of that box. If you are designing new packaging, start by measuring the product and everything that needs to fit inside it.
How much bigger should a box be than my product?
There is no universal answer. The correct allowance depends on your product, material, inserts, required protection and packaging style. For close-fitting custom packaging, Pakko can calculate the appropriate clearance during structural design.
Should I include the box flaps in my measurements?
No. Flaps are part of the box construction and normally are not included in the usable Length × Width × Height measurement.
What units should I use?
Pakko works primarily in millimetres (mm) — for example, 320 × 240 × 85mm.
Can Pakko copy an existing box?
Yes. If you have packaging you would like reproduced or improved, send us the dimensions, photos or preferably an existing sample so we can assess the structure.
What if my product is an unusual shape?
Measure its maximum Length × Width × Height and send Pakko photographs. For complex products, a physical sample may be the easiest way for our structural packaging team to design the correct solution.
Does box size affect shipping costs?
It can. Freight providers may consider both physical weight and the amount of space a parcel occupies. Choosing appropriately sized packaging can therefore help reduce unnecessary packaging volume.
Can Pakko help determine the correct size?
Yes. Provide the product dimensions, photographs, product weight and intended use and our team can help determine an appropriate packaging size and construction.
Keep learning
Related packaging guides
Still not sure?
Don't guess your box dimensions
Send Pakko a photo, your product dimensions or an existing packaging sample and our team can help determine what you need. Whether it's a printed retail carton, ecommerce mailer, shipping carton or complex custom packaging, getting dimensions right at the beginning makes everything easier.
Australian custom packaging, manufactured by Pakko in Brisbane.
Send your measurements
Send your measurements and we'll get back to you within one business day.
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