How to Save Shipping Cost with USPS Priority Mail Cubic?

What is Cubic Pricing?

The cheapest service to deliver packages that are relatively heavy yet small in size is USPS Cubic Pricing via Priority Mail®, which calculates shipping rate based on the package’s dimensions instead of weight.

Cubic Price is an affordable shipping option designed for small yet heavy packages. It applies to packages that weigh less than 20 lbs, measure no more than 0.5 ft3 and the longest dimension may not exceed 18 inches. Customers only pay for the dimensions and shipping distance, instead of the weight.

Thus, it’s the perfect solution for eCommerce stores selling small auto parts, toys, tools, etc., saving up to 89% off compared to other shipping services. 

How to calculate Cubic Tier and shipping rate?

To qualify for Cubic pricing, packages must weigh less than 20 lbs, measure no more than 0.5 ft3 (12 x 12 x 16 inches) and the longest dimension measures no more than 18 inches. The shape of the package can not be rolls or tubes, and there are two different methods to determine the Cubic tier. This is where it gets complicated. 

*Please Note: Measuring Poly Mailers -- The package will be measured as if it's a box. The excess part of the envelope will be calculated.

Method 1.  For Rectangular and Non Rectangular Parcels 

1. Measure length, width, and height of the package separately in inches. 
2. Round down each measurement to the nearest ¼ inch.
3. Multiply the rounded down measurements and divide by 1728

Formula: Length x Width x Height / 1728 = Cubic Feet

4. Round up the number you just calculated (the dividend) and find the appropriate Cubic tier from the chart below. 

Example.

1. Your package weighs 15 lbs and measures 10.4’’ x 8.6’’ x 2.5’’.
2. The measurements round down to 10.25’’ x 8.5’’ x 2.5’.
3. Multiply 10.25’’ x 8.5’’ x 2.5’’ = 217.8125 ft3 
4. 217.8125 1728 = 0.13
5. The Cubic tier for this package is 0.2
   

Although you may not ship tubes or rolls (such as carpets, posters) with Priority Mail Cubic, you can, however, ship padded envelopes and poly softpacks. There’s a different method to calculate the Cubic tier. 

Method 2. For Softpacks and Padded Envelopes

1. Measure length and width of the package separately in inches.
2. Round down each measurement to the nearest ¼ inch.
3. The first two steps are the same as Method 1, but pay attention to the next step.
4. Add the two measurements together.
5. Round up the number you just calculated (the sum) and find the appropriate Cubic tier from the chart below.  

Example.

1. Your envelope weighs 8 lbs and measures 10.8’’ x 8.2’’.
2. The measurements round down to 10.75’’ x 8’’.
3. Add 10.75’’ + 8’’ = 18.75’’ 
4. The Cubic tier for this package is 0.1
   

Please Note: Poly mailer will be measured as if it's a box. The excess part of the envelope will be calculated.

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How Do I Get USPS Cubic Pricing?

With all that said, you’re probably now wondering where to get this amazing service. Cubic via Priority Mail is available through USPS accounts with CPP rates (Commercial Plus Pricing).

You can get deeply discounted shipping labels with these accounts if you ship at a very high volume.

And if you don’t? Then check out ShipSaving, a shipping software designed to help e-commerce businesses, especially small and medium-sized businesses (SMBs) to get started and scale.

‍Register an account now and see the USPS discounts for yourself. Plus, there’s a USPS rebate program, where you can get cash back while you ship.