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Calculate your box’s dimensions to estimate shipping cost

**Co-authored by**Grace Imson, MAand Cheyenne Main

Last Updated: May 14, 2024Fact Checked

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Regardless of which postal service you choose, the cost associated with shipping a package will vary depending on its size. To make sure you’re paying the right amount for shipping, it’s important to know the exact dimensions of the box you’re sending your item in. Use a ruler or measuring tape to find the length, width, and height of the box. You can then use these measurements to calculate other metrics like total size and dimensional weight, which might contribute to the package’s shipping cost.

## Things You Should Know

- Measure the longest side of the package that has a flap attached to it for the length. Measure the other side that has a flap to find the width.
- To find the height of the package, measure the box from top to bottom.
- To get the volume, or cubic size, of the box, multiply the length, width, and height of the box in inches or centimeters.

Method 1

Method 1 of 3:

### Measuring the Dimensions of a Package

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1

**Measure the longest side of the package that has a flap to find the length.**Identify the longest side of the package that has a flap attached to it. Hold a ruler or tape measure up to the edge and read the length of the box from one end to the other. Round your measurement to the nearest 1in (2.5cm) or^{1}⁄_{2}in (1.3cm).^{[1]}- Jot down the measurements on a scrap piece of paper so you can refer to them later.
- Many shipping services only handle packages up to a certain size, which is typically noted in whole inches or centimeters.
- The actual length of your package might vary by
^{1}⁄_{8}in (0.32cm).

2

**Measure the other side with a flap to find the width.**The width is the distance from one “wall” of the shortest side of the box to the opposite wall. Stretch your ruler or tape across the package from edge-to-edge, then round to the nearest 1in (2.5cm) or^{1}⁄_{2}in (1.3cm).^{[2]}- The actual width of your package might vary by
^{1}⁄_{8}in (0.32cm).

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- The actual width of your package might vary by
3

**Measure the side of the box that you don’t close up for the height.**Measure the standing side of the box that doesn’t have a flap attached to one side to record the height. Round the box’s height dimension to the closest 1in (2.5cm) or^{1}⁄_{2}in (1.3cm).^{[3]}- The actual height of your package might vary by
^{1}⁄_{8}in (0.32cm).

**Tip:**If your package has an irregular shape, measure it the same way you would as if it were in a rectangular box, taking the length, width, and height from each of the box’s extreme points.- The actual height of your package might vary by

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Method 2

Method 2 of 3:

### Calculating Volume & Dimensional Weight

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1

**Multiply the length, width, and height of the box to find its volume.**Volume is the same as cubic size, which indicates the amount of space inside the box. If you have a package with a length of 12 inches (30cm), a width of 8 inches (20cm), and a height of 4 inches (10cm), its volume, or cubic size, would be 384 cubic inches (6,290cm^{3}).^{[4]}- Or if you have a box with a length of 12 inches (30cm), a width of 3 inches (7.6cm), and a height of 17.5 inches (44cm), its volume would be 630 cubic inches (10,300cm
^{3}).

- Or if you have a box with a length of 12 inches (30cm), a width of 3 inches (7.6cm), and a height of 17.5 inches (44cm), its volume would be 630 cubic inches (10,300cm
2

**Divide the volume by the shipping carrier’s divisor to find its dimensional weight.**Many major shipping companies use the dimensional (dim) weight to calculate shipping costs.^{[5]}The dimensional weight is based not only on the package’s size but its destination and shipping carrier.- Contact your preferred shipping carrier to find out their specific divisor. Here are the divisors (for Imperial measurements) for a few of the common carriers in the U.S.:
**FedEx:**For U.S., Puerto Rico, or international shipments, divide the cubic size by 139.^{[6]}**UPS:**Divide the cubic size by 139 for Daily Rates and 166 for Retail Rates.^{[7]}**USPS:**If the volume of the package goes over 1,728 cubic inches (28,320cm^{3}), divide the cubic size by 166 and round up to the next whole number.^{[8]}

- For example, if the volume of your box is 384 cubic inches (6,290cm
^{3}) and you’re shipping with FedEx (139), its dimensional weight is 2.76 cubic inches (45.2cm^{3}). - To find the dimensional weight of an irregularly-shaped package, multiply the volume by an adjustment factor of 0.785, then divide the answer by the shipping carrier’s divisor.
^{[9]} - Keep the dimensional weight exact to give you a rough estimate of the box’s shipping costs—try to avoid rounding.

- Contact your preferred shipping carrier to find out their specific divisor. Here are the divisors (for Imperial measurements) for a few of the common carriers in the U.S.:
3

**Weigh your package on a postage scale to determine its actual weight.**Place your package on the scale and wait for it to display a reading. Record the weight without rounding it up because you’ll compare it with the package’s dimensional weight to see how much you can expect to pay for shipping.^{[10]}- You can request to have your package measured at the post office if you don’t own a postage scale.

**Tip:**Having your own postage scale can save you valuable time and energy if you’re a frequent shipper. It’s possible to buy a good postage scale online for as little as $20-30.4

**Compare your package’s actual weight to its dimensional weight.**If the dimensional weight is greater than the actual weight, you’ll pay the dimensional weight price. Most shipping carriers charge whichever of the two weights is greater to maximize their profits per shipment.^{[11]}- It’s important to know the actual weight of your package as well as its dimensional weight since the dimensional weight is only an estimate, not a precise measurement.

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Method 3

Method 3 of 3:

### Finding the Girth and Total Size of a Package

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1

**Double the width and height and add them together to find the girth.**After you find the length, width, and height of the package, multiply the width and height dimensions by 2. Then, add the doubled width and doubled height together. The number you get is the girth of the box.^{[12]}- If your box is 12 inches (30cm) long, 4 inches (10cm) wide, and 6 inches (15cm) tall, doubling the width and height would give you 8 inches (20cm) and 12 inches (30cm).
- When you add 8 inches (20cm) and 12 inches (30cm), the girth is 20 inches (51cm).

- The term “girth” refers to the total distance around the thickest part of the box.
^{[13]}This only applies to the area encircling the shortest side of the package, so the length isn’t required.

- If your box is 12 inches (30cm) long, 4 inches (10cm) wide, and 6 inches (15cm) tall, doubling the width and height would give you 8 inches (20cm) and 12 inches (30cm).
2

**Add the combined length and girth to get your total package size.**When shipping ground packages, you might be asked to provide the overall*size*of the package. To do this, simply add the length and girth measurements together.- If you add a length of 12 inches (30cm) to a girth of 20 inches (51cm), you’d get a total size of 32 inches (81cm).
- If the package you’re shipping is larger than 105 inches (270cm) in combined girth and length, you may be charged an additional special handling fee.
^{[14]}- The maximum size for most packages is 130 inches (330cm). The maximum weight is 70 pounds (32kg) for international packages and 50 pounds (23kg) for U.S. ground packages.
^{[15]}

- The maximum size for most packages is 130 inches (330cm). The maximum weight is 70 pounds (32kg) for international packages and 50 pounds (23kg) for U.S. ground packages.

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## Community Q&A

Search

Question

How do I calculate the volume of an object whose dimensions are L=320, b=160, and h=110?

Community Answer

Multiply the length by the base (or width) by the height.

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Not Helpful 6Helpful 34

Question

How do I find the length, breadth and height of a tank?

Community Answer

Height is the ground to the top, length is the diameter and breadth is the distance around the tank.

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Question

How do I know what size shipping box I need?

Community Answer

Measure the item length, width and height of the item you wish to ship. Find a box that is large enough to fit the object in.

**Thanks! We're glad this was helpful.****Thank you for your feedback.**

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## Video

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## Tips

On regular slotted cartons (RSCs), the most common type of shipping box, both horizontal surfaces are identical, meaning either end could be used as the top or bottom.

^{[16]}Thanks

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If you’re packing your item in a specialty box provided by a manufacturer or shipping company, look for visual clues like logos and text to determine its correct orientation.

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Different shipping services have different guidelines and restrictions in terms of size and weight. Check the pricing policies of each shipping service to find which one will work best for your budget.

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## Things You'll Need

- Ruler or tape measure
- Postage scale (optional)

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## Expert Interview

Thanks for reading our article! If you’d like to learn more about geometry, check out our in-depth interview with Grace Imson, MA.

## References

- ↑ https://www.scientificamerican.com/article/bring-science-home-juice-box-geometry/
- ↑ https://www.scientificamerican.com/article/bring-science-home-juice-box-geometry/
- ↑ https://www.scientificamerican.com/article/bring-science-home-juice-box-geometry/
- ↑ https://www.bbc.com/bitesize/articles/z3jrxfr
- ↑ https://www.fedex.com/en-us/shipping/packaging/what-is-dimensional-weight.html
- ↑ https://www.fedex.com/en-us/shipping/packaging/what-is-dimensional-weight.html
- ↑ https://www.ups.com/us/en/support/shipping-support/shipping-dimensions-weight.page
- ↑ https://pe.usps.com/text/dmm300/123.htm?_gl=1*1dnx4zo*_gcl_au*MTU0MjczNjY3Ny4xNzA2MDUzOTg4*_ga*NDQwNDExNjQ4LjE3MDYwNTM5ODk.*_ga_3NXP3C8S9V*MTcwNjA1Mzk4OC4xLjEuMTcwNjA1NDAxOS4wLjAuMA..#a_1_3
- ↑ https://pe.usps.com/text/dmm300/123.htm?_gl=1*1dnx4zo*_gcl_au*MTU0MjczNjY3Ny4xNzA2MDUzOTg4*_ga*NDQwNDExNjQ4LjE3MDYwNTM5ODk.*_ga_3NXP3C8S9V*MTcwNjA1Mzk4OC4xLjEuMTcwNjA1NDAxOS4wLjAuMA..#a_1_3

More References (7)

- ↑ https://www.usps.com/business/verify-postage.htm
- ↑ https://www.fedex.com/en-us/shipping/packaging/what-is-dimensional-weight.html
- ↑ https://www.usu.edu/math/koebbe/online_math_1100/lesson_examples/section3.4/problem33.pdf
- ↑ https://www.fedex.com/content/dam/fedex/us-united-states/services/GrlPkgGuidelines_fxcom.pdf
- ↑ https://www.fedex.com/content/dam/fedex/us-united-states/services/Fees_Shipping_Information.pdf
- ↑ https://pe.usps.com/businessmail101?ViewName=MinMax
- ↑ https://www.iopp.org/files/fibrebox_association_box-styles_basics.pdf

## About This Article

Co-authored by:

Grace Imson, MA

Math Teacher

This article was co-authored by Grace Imson, MA and by wikiHow staff writer, Cheyenne Main. Grace Imson is a math teacher with over 40 years of teaching experience. Grace is currently a math instructor at the City College of San Francisco and was previously in the Math Department at Saint Louis University. She has taught math at the elementary, middle, high school, and college levels. She has an MA in Education, specializing in Administration and Supervision from Saint Louis University. This article has been viewed 722,312 times.

2 votes - 100%

Co-authors: 22

Updated: May 14, 2024

Views:722,312

Categories: Postal System | Business Shipping and Delivery

Article SummaryX

To measure the dimensions of a shipping box, start by measuring one of the long sides of the package from one end to the other with a measuring tape, measuring stick, or ruler. This measurement will be the length. Write down the number so that you don’t forget. Next, turn your measuring tool 90 degrees and measure along one of the short sides of the package to find the width. Finally, hold the tool vertically and measure from the top of the box to the bottom to find the height. If you need to find the girth of the package, multiply the width and the height times 2 and add both of the resulting numbers together. For instance, if your package is 6 inches (15 cm) high and 4 inches (10 cm) wide, the girth would be 20 inches (51 cm). Add the length to the girth to get the total package size. For instance, if your package is 12 inches (30 cm) long, and the girth is 20 inches (51 cm), then the total size would be 32 inches (81 cm). If you need to find the volume, or cubic size, of the package, multiply length times width times height. In our example, the package would have a volume of 288 cubic inches (4719 cubic cm). If you need to find out the package’s dimensional weight, divide the volume by 166 (if you’re shipping within the US) or 139 (if you’re shipping internationally). If you can, weigh the package on a scale to check its actual weight against the dimensional weight. Your shipping costs will likely be based on whichever number is bigger. Read on to learn how to measure the dimensional weight of your packages!

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## Reader Success Stories

Harry Booker

Oct 17, 2016

"The specific details on how to measure were very helpful. Also, the calculation of the girth was helpful."

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