Choosing the right corrugated box size is one of the most practical decisions you'll make for your business. The wrong size means wasted void fill, higher shipping costs, and products that shift in transit. The right size means a clean, professional shipment and lower per-unit packaging costs.

Here's how to figure out exactly what you need.

How to Measure Your Product

Before picking a box, measure your product at its widest points — length, width, and height. These are the interior dimensions you need the box to accommodate. Always measure in the order Length × Width × Height (L×W×H).

Add a small buffer — typically 1 to 2 inches on each side if you're using void fill or wrapping material. If your product is a rigid item going straight into the box with no padding, you can go with a tighter fit.

Understanding Corrugated Box Sizes

Corrugated boxes are measured by their interior dimensions. A box listed as 12×10×8 means the inside of the box is 12 inches long, 10 inches wide, and 8 inches deep. This is the space your product needs to fit into.

When browsing sizes, keep in mind:

• Small boxes (6" to 11") — best for compact items, small parts, cosmetics, and retail goods. Light and easy to handle.
• Medium boxes (12" to 15") — the most versatile range. Good for e-commerce orders, food packaging, and general retail shipping.
• Large boxes (16" to 20") — suited for bulkier items, multi-product orders, and larger retail goods.
• Oversized boxes (21" to 36") — moving, furniture parts, industrial equipment, and anything that doesn't fit a standard range.

What Is 32C Kraft Corrugated?

Most standard shipping boxes — including all of Prime Carton's in-stock sizes — are made from 32 ECT (Edge Crush Test) single wall Kraft corrugated board. This is the industry standard for everyday shipping and storage. It handles the typical bumps, stacking, and humidity of regular transit without being unnecessarily heavy or expensive.

For heavier items or anything being stacked under significant weight, double wall corrugated (which uses two layers of fluting) offers significantly more crush resistance.

Choosing Based on Use Case

E-commerce and order fulfillment: Go for a snug fit. Oversized boxes increase dimensional weight charges from couriers. A box that fits your product with 1–2 inches of buffer on each side is ideal.

Moving and storage: Use medium to large boxes for most household items. Keep heavy items like books in small boxes — a large box packed with books becomes impossible to lift safely.

Retail and distribution: Your box size should fit your product plus any retail packaging or inserts. Consistency across your product line makes palletizing and warehouse stacking much more efficient.

Food and beverage: Size for your product configuration — whether that's a single item, a pack, or a case. If your product is temperature-sensitive, a tighter fit helps maintain pack integrity.

A Practical Sizing Example

Say you're shipping a product that measures 9×7×5 inches. You'd want a box with interior dimensions of roughly 11×9×7 — giving you about an inch of clearance on each side for light void fill. That falls squarely in Prime Carton's 12"–15" size range.

Custom Sizes vs. Stock Sizes

If your product fits one of our standard sizes, in-stock boxes are the fastest and most cost-effective option. They ship flat, are available in bundle quantities, and can be ordered online.

If your product has unusual dimensions — very flat, very long, or an irregular shape — a custom corrugated box manufactured to your exact specifications will reduce void fill costs and give your product a cleaner fit. Prime Carton manufactures custom sizes at our Scarborough facility.

Need Help Choosing?

Browse our corrugated boxes by size range — 6" to 11", 12" to 15", 16" to 20", and 21" to 36" — or request a custom quote if you need something built to spec. We deliver to businesses throughout the Greater Toronto Area from our Scarborough facility.