Corrugated Box Sizes Guide

A complete reference for corrugated box sizing — standard dimensions, how to measure, flute profiles, and how box size affects shipping costs.

How Corrugated Boxes Are Measured

Corrugated box dimensions are always expressed as Length × Width × Height (L × W × H), measured from the inside of the box. This is an important distinction — outside dimensions will be slightly larger due to the thickness of the corrugated board itself.

Length is the longest side of the box opening. Width is the shorter side of the box opening. Height is the distance from the bottom to the top (the flap side). When you look down at an open box, length is the longer dimension and width is the shorter dimension of the rectangular opening.

Standard Corrugated Box Sizes

Stock sizes are boxes kept in inventory by suppliers — they ship faster and cost less than custom sizes because they require no custom tooling. Here are the most common stock sizes in the US market:

Small Boxes (up to 12")

Size (L × W × H)	Typical Use	Approx. Volume
4 × 4 × 4"	Small parts, samples, candles	0.04 cu ft
6 × 6 × 6"	Mugs, small bottles, jars	0.13 cu ft
8 × 6 × 4"	Books, small electronics	0.11 cu ft
10 × 8 × 6"	Shoes, toys, multiple small items	0.28 cu ft
12 × 10 × 8"	Medium products, clothing bundles	0.56 cu ft
12 × 12 × 12"	General purpose, multi-item orders	1.0 cu ft

Medium Boxes (12" - 24")

Size (L × W × H)	Typical Use	Approx. Volume
14 × 14 × 14"	Medium products, small appliances	1.6 cu ft
16 × 12 × 12"	Bulk shipments, housewares	1.3 cu ft
18 × 14 × 12"	Clothing, medium electronics	1.75 cu ft
18 × 18 × 18"	General purpose, moving	3.4 cu ft
20 × 16 × 14"	Larger products, multi-piece	2.6 cu ft
24 × 18 × 18"	Large items, bulky shipments	4.5 cu ft

Large Boxes (24"+)

Size (L × W × H)	Typical Use	Approx. Volume
24 × 24 × 24"	Large/heavy items	8.0 cu ft
30 × 20 × 20"	Furniture components, bulk	6.9 cu ft
36 × 24 × 24"	Very large items	12.0 cu ft
48 × 24 × 24"	Industrial, long items	16.0 cu ft

Flute Types and Thickness

The flute (the wavy layer inside corrugated board) determines the box's thickness, cushioning ability, and print surface quality. Flute choice is one of the most important decisions in box specification.

Flute	Height	Flutes/ft	Best For
A-Flute	3/16"	33-36	Maximum cushioning, fragile items
B-Flute	1/8"	47-52	Die-cuts, displays, smooth print surface
C-Flute	5/32"	38-42	Standard shipping boxes (most common)
E-Flute	1/16"	90-98	Retail packaging, mailer boxes
F-Flute	1/32"	125+	Micro-flute, replaces folding cartons

How Box Size Affects Shipping Costs

Modern shipping pricing is largely based on dimensional weight (DIM weight), which means the size of your box matters as much as — or more than — its actual weight. DIM weight is calculated by multiplying L × W × H and dividing by a DIM factor (typically 139 for domestic carriers). If the DIM weight exceeds the actual weight, you're billed for the DIM weight.