Package dimensions are a key pricing factor in shipping rates from all carriers, including USPS and FedEx.

This makes measuring your shipping boxes a key step in accurately estimating your shipping costs. Shipping companies charge extra for oversized and unusually sized boxes, so it’s best to get your dimensions right to avoid surcharges.

Grab a measuring tool like a tape measure to take the length, width, and height of shipping boxes. In this article, we show you how to measure your boxes for accurate shipping rates, including all important dimensions:

Length
Width
Height
Girth

Our free shipping rate calculator gives you instant quotes for shipping rates. Just enter your shipping destination and weight for the cheapest and fastest rates from all available couriers.

How to Measure Length for Shipping Boxes

How to measure a box starts with finding the longest side. This is because length is the largest measurement of most shipping boxes, which are expressed as:

Length x Width x Girth

Next, grab your measuring tape or ruler to figure out the package dimensions. Hold your measuring tool to the edge of the longest side to find the total length from end to end. You can round your box length measurement to the nearest inch or centimeter.

Length is the most important dimension for shipping boxes because couriers use it to determine whether a package is oversized. For example, UPS labels any package longer than 108 inches as oversized, which costs more to ship.

Be sure to record your length measurements for the package dimensions. First, length is a factor in package girth, which we'll discuss later. Secondly, if you use shipping software, you’ll need to enter the dimensions of your commonly used boxes. Accurate dimensions allow the shipping platform to give you accurate, pre-calculated shipping costs in checkout for your shipments.

How to Measure Width for Box Measurements

The width of your shipping box is the surface on the shortest side. To measure the width of your box, turn your measuring tool 90 degrees from the long side. Record the package dimensions from one edge to the other, as you’ll need it later to calculate the girth of the package.

Shipping box width isn’t as important as length. This is because couriers assess rates by the longest side, and package width is rarely greater than length.

How to Measure Height for Box Measurements

To measure box height, hold your measuring tool vertical up in the air. Measure this standing side, rounded to the nearest inch or centimeter, and record the number of the package dimensions.

Like box width, height isn’t likely to impact your costs. This is because, on many standard shipping boxes, height and width are identical. Or, height will be your smallest measurement and have no impact on cost.

How to Measure Girth for Box Measurements

How to measure girth for shipping boxes is simple.

Just double your measurements for both width and height, then add them together for the girth measurement. Alternatively, you can multiply both your dimensions for width and height by two, then add them together.

Girth is the total distance around the thickest section of a shipping box. Couriers often ask for girth on volumetric shipments, such as USPS Cubic.

How to Calculate Total Size for Box Measurements

To calculate the total size of your package, just add the girth measurement to the length measurement. For example, if your girth measurement was 40 inches and your length was 30, your shipping box would be 70 inches.

Couriers also use total package size – length x girth – to determine if packages incur oversize charges. UPS, for example, requires packages to be less than 165 inches in combined length and girth to not incur cost extra to ship.

Shipping Box Costs by Size

Unless oversized, the size of your shipping boxes won’t increase your cost of shipping. In fact, courier companies like USPS let you order free shipping boxes in various shapes and sizes on their website.

Looking for free shipping boxes? Here’s a guide to ordering free boxes.

Large and oddly shaped boxes, however, can cost more to ship. For example, bike boxes. Long lengths are hard for drivers to move and often require special services. Secondly, a heavy bike upwards of 50-70 pounds will run into a heavy item surcharge of $24 from UPS and FedEx.

Flat Rate boxes can be a good way to ship heavy items over greater distances, cheaply. This is because Flat Rate services are a single rate for any item below 50 or 70 pounds, courier depending. The drawback is Flat Rate boxes are all of the typical dimensions, so they’re of no help when trying to ship outsized or odd-shaped items.

Package Dimensions & the Limits by Carrier

At what size does your carrier consider a package “oversized” and charge extra? Here’s the breakdown for common US carriers on domestic shipments:

USPS Package Size Limit

The maximum weight is 70 pounds
The maximum size is 108 inches in combined length/girth
The maximum length is 130 inches (must use USPS Retail Ground, also incurs an oversized charge)

UPS Package Size Limit

The maximum weight is 150 pounds
The maximum size is 165 inches in combined length/girth
The maximum length is 108 inches

FedEx Package Size Limit

The maximum weight is 150 pounds
The maximum size is 165 inches in combined length/girth
The maximum length is 119 inches

How to Measure a Box with Easyship Shipments

If you use Easyship for eCommerce, you'll want to input the dimensions of your typical box sizes before you ship. Our shipping automation can calculate accurate shipping rates for all your shipments in real-time with dimensions entered.

This automated shipping feature is called Rates at Checkout. It displays three accurate rates for customers in the checkout based on their order specifics.

Your shoppers value cost transparency, and are actually more likely to complete a purchase with options for shipping. 2 in 3 shoppers say they buy from a brand based on the available shipping and delivery options.

Some buyers may want budget shipping while others may be willing to pay extra for expedited delivery. Rates at Checkout gives every customer the flexible, frictionless checkout experience they expect – without any effort from you. To learn more about Rates at Checkout, head over to the feature page.

As a final note, be sure to measure your shipping boxes accurately. It only takes one fee from USPS or FedEx for a wrong-sized package to make you want to get your numbers right.

With Easyship, you’ll always use the right-sized box for your package. Rates at Checkout guarantees it. You can create a free Easyship account to try all our features free for 50 shipments per month, forever. You’ll also get up to 70% off all couriers’ rates on all shipments.