What is Priority Mail Cubic?

Priority Mail Cubic is a specialized service offered by the United States Postal Service (USPS) that prices packages based on their outer dimensions rather than weight. This unique pricing model can lead to significant savings, especially for small, dense packages weighing up to 20 pounds.

Key Features:

• Dimension-based pricing: Rates determined by package size, not weight
• Weight limit: Up to 20 pounds
• Delivery timeframe: 1-3 business days
• Insurance: $100 included for free
• Tracking: Free package tracking included
• Savings: Up to 90% off retail shipping rates

USPS Cubic Pricing Tiers

Priority Mail Cubic uses a tiered pricing system based on the package's volume. There are five tiers:

1. Tier 0.1: Up to 0.1 cubic feet
2. Tier 0.2: 0.101 to 0.2 cubic feet
3. Tier 0.3: 0.201 to 0.3 cubic feet
4. Tier 0.4: 0.301 to 0.4 cubic feet
5. Tier 0.5: 0.401 to 0.5 cubic feet

Calculating Your Package's Cubic Tier

For Boxes and Rigid Packages:

1. Measure the outer dimensions (length, width, height) in inches
2. Round each measurement down to the nearest quarter inch
3. Multiply length x width x height
4. Divide the result by 1728 (cubic inches in a cubic foot)
5. The result is your package's cubic feet measurement

Example: For a box measuring 12.3" x 9.5" x 3":

• Round down to 12.25" x 9.5" x 3"
• 12.25 x 9.5 x 3 = 349.125
• 349.125 / 1728 = 0.202 cubic feet
• This package falls into the 0.3 cubic feet pricing tier

Note: Maximum size for any single dimension is 18 inches

For Envelopes and Soft Packs:

1. Measure the length and width of the empty envelope
2. Round down to the nearest quarter inch
3. Add the length and width together
4. Use the total to determine the pricing tier:
   • Tier 0.1: Up to 21"
   • Tier 0.2: 21.01" to 27"
   • Tier 0.3: 27.01" to 31"
   • Tier 0.4: 31.01" to 34"
   • Tier 0.5: 34.01" to 36"

Restrictions

• Tubes and rolls are not eligible for Cubic pricing
• Maximum combined length and girth is 84 inches

Benefits of Using Priority Mail Cubic

1. Cost savings: Cheaper than weight-based pricing for small, heavy items
2. Predictable pricing: Easy to calculate shipping costs based on box dimensions
3. Fast delivery: 1-3 business day delivery to any US address, including PO boxes
4. Free tracking: Monitor shipments at no extra cost
5. Included insurance: $100 of coverage with every shipment
6. No surcharges: Residential and fuel surcharges included in the price

Tips for Maximizing Savings

1. Optimize packaging: Use the smallest box possible that safely fits your items
2. Consider breaking up large orders: Sometimes shipping in multiple smaller boxes can be cheaper
3. Use cubic feet calculators: Online tools can help quickly determine your package's tier
4. Compare rates: Always compare Cubic rates with other shipping methods
5. Use Commercial Pricing: Accessing Commercial Pricing rates can lead to even more savings

2024 USPS Priority Mail Cubic Rates

Accessing Priority Mail Cubic Rates

Priority Mail Cubic isn't available at regular Post Office counters. However, many online shipping platforms and 3PL providers offer access to these rates. By partnering with a fulfillment provider, you can easily access these discounted rates and streamline your shipping process. For small-scale sellers not yet ready for a 3PL, Pirate Ship offers free access to USPS Priority Mail Cubic rates with no monthly fees or minimums.