What Is the Size of Parcel?

May 5, 2023 Joe Jordan

The USPS handle millions of packages every day, ranging from small items like jewelry to large items like car engines and commercial furniture. Among packages, there is a special subset referred to as parcels.

In this blog, we will explore what a parcel is, what are the size and weight limits, parcel shipping charges, and other properties of parcels.

What Is Parcel Size in Shipping?

In shipping, parcel size refers to how big or small a package is. Parcel size is defined by the following measurements:

  • -Height
  • -Width (Girth)
  • -Length

Parcel size may also refer to the parcel’s weight in addition to its dimensional size.

How Does USPS Determine Package Size?

In order to ensure packages are machinable, USPS needs to ensure they are within the allowed range of weight and size. To determine the size and weight of a package, USPS does three things:

  • -Weighing package on a scale
  • -Measuring package dimensions
  • -Calculating dimensional weight

Step 1: USPS Actual Weight

Finding the actual weight of a package is easy since it just involves setting the package on a normal scale and recording the reading.

Step 2: Measuring package dimensions

USPS staff at post office locations can help you measure your package length, width, and height.

Step 3: Calculating dimensional weight

Dimensional weight formula: Dimensional Weight = (L x W x H) ÷ Divisor

USPS uses the following procedure to get your package’s dimensional weight:

  • -Find the height, girth, and length of the package in inches. Then round up each measurement to the nearest whole number.
  • -Multiply the package dimensions (length x width x height). The result of this multiplication is called the cubic size (volume).
  • -Finally, divide the cubic size by the divisor (USPS uses 166) to get the dimensional weight in pounds. Round up any fraction or decimal number to the next whole pound.

Step 4: Get the billable weight

The postage price is calculated based on the package’s weight. But which one does USPS use; Actual weight or Dimensional weight?

Whichever is higher between the two is the weight used to calculate shipping prices.

USPS Minimum and Maximum Package Sizes

USPS Minimum Package Size

The Postal Services states that all mailpieces MUST be at least 0.007 inches thick. If a mailpiece is 0.25 inches thick or less, it MUST be rectangular and MUST be at least 3-1/2 inches high by 5 inches long.

USPS Maximum Package Size

The largest allowed size for most USPS mailpieces is 108 inches in combined length and girth. For USPS Retail Ground, mailpieces may measure up to 130 inches in combined length and girth. However, they will be charged oversized prices.

Regardless of the size of the mailpiece, the maximum mailable weight of any mailpiece is 70 pounds. Some classes of mail have lower weight limits.

USPS Shipping Rates by Weight Chart


USPS Service


Priority Mail Express

Priority Mail

USPS Retail Ground

1-5 pounds




6-10 pounds




11-15 pounds




16-20 pounds




21-25 pounds




26-30 pounds




31-35 pounds




36-40 pounds




41-45 pounds




46-50 pounds




51-55 pounds

$151.70-$ 541.20



56-60 pounds




61-65 pounds

$179.85-$ 640.80



66-70 pounds




For more details, check out the USPS rate manual.

What is the largest package USPS will accept?

The largest package USPS will accept is a 70 lb package.

What is the largest package USPS will ship internationally?

USPS international shipping services have a weight limit of 70 pounds, just like domestic USPS services.

How ShipSigma Can Help You Save Money On Shipping

If you ship with UPS or FedEx, ShipSigma can help you save money on shipping. Regardless of whether the parcels you ship are big or small, we’re sure you want your rates to be low rather than high.

With over 250 years of combined shipping industry experience and AI-powered industry-leading software, it's only a matter of time before we lower your shipping rates. And that’s a guarantee.

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