How to Measure Packaging Box Dimensions

Hello! If you’re getting started with your first custom packaging order, welcome. It’s an exciting step for your brand, and we’re here to help.

One of the very first questions we, as your packaging partner, will ask is, “What dimensions do you need?” This might seem like a simple question, but getting it right is one of the most important parts of the entire process. 

This guide is here to walk you through exactly how to measure packaging box dimensions correctly, so you can order with confidence. Let’s make sure your product fits perfectly from day one.

Why Accurate Measurements Are for Packaging Box

You might be thinking, “It’s just a box, how hard can it be?” But in the world of custom manufacturing, even a small miscalculation can lead to big problems. Accurate measurements are crucial for two main reasons:

1. Product Fit and Security: This is the most important one. The last thing you want is your beautiful product rattling around in a box that’s too big, or not fitting at all. A snug, secure fit protects your item from damage and gives your customer a professional, high-end unboxing experience.
2. Accurate Shipping Costs: Box size directly impacts your shipping expenses. An oversized box not only costs more to produce but can also increase your shipping fees (due to dimensional weight), eating into your profits.

Understanding the Two Types of Box Measurements

Before you grab a ruler, it’s essential to know what you’re measuring. When it comes to custom packaging, there are two distinct sets of dimensions that we talk about: internal vs external box dimensions.

What Are Packaging Box Internal Dimensions?

These are the measurements of the inside of the box. Think of it as the usable, empty space where your product will go. 

As our customer, this is almost always the measurement you should focus on. It tells us how big to make the box to perfectly hold your item.

What Are Packaging Box External Dimensions?

These are the measurements of the outside of the box, from one outer edge to the other, including the thickness of the box material. 

These dimensions are less about product fit and more about logistics, like how many of your boxes will fit inside a larger shipping carton or how much space they will take up on a storage shelf.

The Standard Formula: Length x Width x Depth (L x W x D)

In the packaging industry, we always follow a standard formula to avoid confusion. Knowing how to measure L x W x D correctly is key to communicating your needs clearly.

• Length (L): This is the longest side of the box’s opening when you’re looking down into it.
• Width (W): This is the shortest side of the box’s opening.
• Depth (D): This is the “height” of the box, measuring from the bottom up to the top opening.

How to Correctly Measure Internal Box Dimensions

This is the measurement we’ll need 99% of the time. Here’s how to get it right.

First, choose your tool. For most product boxes, a simple ruler or tape measure is all you need. If you’re working with very small items (like jewelry) and need high precision, a vernier caliper is an excellent tool.

Now, for the technique:

1. Assemble the box if it’s flat, or grab an existing sample.
2. Place your ruler or tape measure on the inside of the box.
3. To find the internal Length: Measure the inside of the box from one crease line to the opposite crease line (on the longest side).
4. To find the internal Width: Do the same for the shortest side of the opening.
5. To find the internal Depth: Measure from the bottom crease (where the base folds up) straight up to the top edge of the box.

How to Correctly Measure External Box Dimensions

Measuring the exterior is more straightforward. Simply lay your fully assembled box down and use your tape measure to find the total length, 

width, and depth from one outermost edge to the other. This is most useful for your own storage or master carton calculations, but less common for placing the initial order.

Common Mistakes to Avoid When Measuring

As your packaging partner, we’ve seen a few common slip-ups. Here are the main ones to watch out for in this box measurement guide:

• Mixing up Length and Width: Always remember, Length is the longest side of the opening. Providing these numbers in the wrong order (e.g., 4″ L x 6″ W) can result in a box that is the wrong shape.
• Measuring the Product, Not the Box: This is the biggest one! Don’t just give us the exact dimensions of your product. You must account for…
• Forgetting “Clearance” or “Wiggle Room”: You need to add a little extra space so your product can be inserted and removed easily. We recommend adding at least 1/8 inch (or 3-4mm) to each of your product’s dimensions. This new, larger number will be your ideal internal box dimension.
• Measuring a Rough Handmade Prototype: If you’ve folded a sample by hand, it might not be perfectly square. Always try to measure from the intended crease lines, not just the cut edges, to ensure your final manufactured boxes will be uniform.

How to Provide Your Dimensions to Your Packaging Supplier

You’ve got your numbers! Now, how do you send them to us? To make the process of measuring for custom packaging perfectly smooth, please follow these simple rules:

1. Always provide the internal dimensions unless we specifically ask for the external.
2. Clearly label your measurements in the L x W x D format. (e.g., 6″ L x 4″ W x 2″ D).
3. Always state your units. Clearly write “inches” (or “) or “centimeters” (cm) to avoid any confusion.

Following these steps ensures that the quote we provide is accurate and the first sample we make is a perfect fit. At MJCPack, our goal is to make this process as easy as possible for you.

Still unsure? Let our packaging experts help you find the perfect fit.