A frequent but overlooked issue in custom packaging projects is miscommunication about dimensions. Buyers send a set of length‑width‑height values. After mass production, products cannot fit inside boxes or inner inserts do not match. Some orders pass production check but bring unexpected high shipping costs.
Most of these troubles come from confusing inner dimensions and outer dimensions. Buyer and manufacturer interpret size reference differently, and heavy losses happen after goods are finished.
1. What is Inner Dimension
Inner dimension: the usable inner space of a closed box, L×W×H.
👉Use for fitting your product, inserts and accessories. If you need your item to fit well inside the box, you should specify inner dimensions.
Example: Your item measures 80×50×20 mm. If you want the box to hold this product, specify inner size 80×50×20 mm. Board thickness will make outer size slightly larger automatically.
2. What is Outer Dimension
Outer dimension: overall outside size including paper‑board thickness after box closure.
👉Freight forwarders, Amazon warehouses and container loading all calculate volumetric weight based on outer dimensions.
For a rigid gift box with inner size 80×50×20 mm and 2 mm board thickness, outer dimension becomes 84×54×24 mm.
If you mistakenly treat outer size as inner specification, finished box inner cavity will be too small for your goods.
3. Four Common Costly Pitfalls
❌Pitfall 1: Only send numbers without marking inner or outer. Gift‑box factories often work from inner size, while corrugated carton factories may use outer size by default. Without written note, misunderstanding is very likely.
❌Pitfall 2: Measure sample outer surface and use that number as required inner space. What you measure on the outside is outer dimension, which will result in insufficient inner cavity.
❌Pitfall 3: Estimate shipping cost using inner measurements. Carriers calculate dim‑weight from outer size. Budget based on inner size will under‑estimate real freight.
❌Pitfall 4: Design inner inserts against outer dimension. Paper or EVA inserts will be too big to fit inside box cavity.
4. Practical Buying Tips For Overseas Brands
① Always mark Inner / Outer when submitting dimensions. Example: Box inner size: 80×50×20 mm. Never send raw numbers only.
② If you have physical sample: measure inner cavity for inner dimension, also measure outer shell, send both sets to your supplier.
③ Design inserts based on box inner dimension, not outer dimension.
④ For container planning, freight calculation and FBA preparation, always refer to outer dimensions.
⑤ After receiving pre‑production samples, double‑check both inner and outer size, confirm product fits properly before approving mass‑production.
Box dimensions are the foundation of custom packaging. Missing inner‑outer reference may cause rework, scrap goods and extra logistics expense. Always clarify size reference during quotation and pre‑production confirmation to prevent avoidable losses.