Corrugated Box Sizing: How to Measure and Choose the Right Size
Too big = wasted shipping cost. Too small = product doesn’t fit. Learn how to measure your product and choose the right corrugated box size. Chengtop Packaging’s sizing guide.
- Understand internal vs. external dimensions
- Know how to measure your product
- Learn the 5mm rule for fit
- Compare standard box sizes
- Avoid oversize shipping costs
- Avoid common sizing mistakes
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Description
Size Matters
The right box size protects your product AND saves shipping money. Too big and you pay for air. Too small and your product doesn’t fit.
Internal vs. External Dimensions
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Type
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What It Means
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Internal dimensions
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Space inside the box (where product sits)
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External dimensions
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Outside size (for shipping cost calculation)
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Rule: Always specify internal dimensions when ordering.
How to Measure Your Product
- Measure length, width, and height
- Add padding space (at least 5–10mm each side)
- Choose the box that fits snugly
The 5mm Rule
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Gap
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Problem
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Too tight
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Product doesn’t fit
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Snug (5mm gap)
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Perfect — product fits with padding
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Too loose (20mm+)
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Product rattles, wasted space
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Standard Box Sizes
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Box Size
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Best For
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Small (100×100×100mm)
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Small products, accessories
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Medium (200×150×100mm)
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Most e-commerce products
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Large (300×200×200mm)
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Larger items, multiple products
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Extra large (400×300×300mm)
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Bulky items, multi-item orders
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Why Size Affects Cost
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Factor
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Impact
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Box size
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Bigger box = more material cost
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Shipping size
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Dimensional weight = more cost
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Void fill
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Bigger box = more packing material
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Storage
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Bigger box = more warehouse space
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Right Size = Right Cost
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Box Size
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Relative Cost
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|
Perfect fit
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1× (base)
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10% too big
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+10–15%
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30% too big
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+30–40%
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Common Sizing Mistakes
- Measuring external, not internal — Product doesn’t fit
- No padding space — Product touches box, gets damaged
- Box too big — Product rattles, wasted shipping cost
- Ignoring dimensional weight — Shipping costs more than expected
- No sample test — Box doesn’t fit actual product
Ready to Size Your Boxes?
Tell us your product dimensions — we’ll recommend the right box size and flute profile.
Email: chengtop888@outlook.com
WhatsApp / Phone: +86 15272060604
