How to Choose the Right Shipping Box Size

Choosing the right shipping box size is one of the fastest ways to cut shipping costs and reduce damaged deliveries. A box that's too big wastes void fill and invites crushing; a box that's too small splits at the seams. This guide gives you a repeatable method to size boxes for any product.

Why box size matters more than you think

Carriers increasingly bill by dimensional weight — a formula based on a package's volume, not just its actual weight. An oversized box for a light product means you pay for air. The right-sized box lowers your billed weight, uses less protective filler, and arrives intact more often.

Measure your product first

Measure the longest, widest and tallest points of your product, including any handles or protrusions. Then add clearance for cushioning:

• Light, sturdy items: 2.5–5 cm (1–2 in) of space on each side.
• Fragile items: 5 cm (2 in) minimum, more for glass or electronics.
• Multiple items: measure the combined footprint when packed together, not each item alone.

Your ideal internal box dimensions are the product size plus that clearance on every axis.

Match the box to the product, not the other way around

Stocking two or three box sizes covers most single-product orders. A medium corrugated shipping box handles the bulk of everyday e-commerce parcels, while a large corrugated shipping box suits bundles and bigger goods. For flat or soft items, a padded mailer is cheaper and lighter than any box.

Don't forget board strength

Size is only half the equation — the board grade (single vs. double wall) determines how much weight the box can carry and stack. Heavier or denser products need double-wall board even in a small footprint. When in doubt, choose the sturdier grade; the cost difference is tiny next to a damaged order and a refund.

A quick sizing checklist

1. Measure the product (L × W × H), including protrusions.
2. Add cushioning clearance on every side.
3. Pick the nearest stock box at or just above those internal dimensions.
4. Confirm the board grade suits the product weight.
5. Test-ship one parcel before committing to a size for a whole product line.

Ready to stock the right sizes?

Browse our full range of shipping boxes to find the sizes and board grades that fit your products — available at wholesale prices with fast delivery. Getting box size right pays for itself in lower postage and fewer returns.