USPS Priority Mail Flat Rate Box Size Chart

USPS Priority Mail Flat Rate boxes come in 5 standard sizes: Small (8-11/16 × 5-7/16 × 1-3/4), Medium (two variants), Large, and Large Board Game. Flat Rate pricing is based on the box, not weight — ideal for heavy, small shipments.

Quick facts

In-stock options

• 20" Metal Wardrobe Hanger Bar - 150lb Capacity, Silver Steel
  $5.22In stock
• 6x4x4 ECT-32 Kraft Corrugated Boxes - Standard Strength Shipping, Bundle of 25
  $8.03In stock
• 6x5x5 ECT-32 Kraft Corrugated Boxes - Standard Strength Shipping, 25-Pack
  $8.26In stock
• 6x5x4 ECT-32 Kraft Corrugated Boxes - Standard Strength Shipping, 25-Pack
  $8.49In stock
• 6x6x4 ECT-32 Kraft Corrugated Boxes - 25 Pack Bulk Shipping
  $8.75In stock
• 7x5x4 ECT-32 Kraft Corrugated Boxes - Reliable Shipping, Bundle of 25
  $8.82In stock
• 5x5x5 ECT-32 Kraft Corrugated Cube Boxes - 25 Pack Bundle
  $9.00In stock
• 6x6x3 ECT-32 Kraft Corrugated Boxes - 25-Box Bundle
  $9.29In stock
• 8x4x4 ECT-32 Kraft Corrugated Long Boxes - Easy Pack Design, Bundle of 25
  $9.42In stock
• 7x4x4 ECT-32 Kraft Corrugated Boxes - Industrial Strength Shipping, 25-Pack
  $9.47In stock

Also stocked

• 5x4x4 ECT-32 Kraft Corrugated Boxes - Standard Strength Shipping, Bundle of 25
  $9.53In stock
• 9x5x5 ECT-32 Kraft Corrugated Boxes - Standard Strength Shipping, Bundle of 25
  $9.55In stock
• 8x5x5 ECT-32 Kraft Corrugated Boxes - 25/Bundle Industrial Shipping
  $9.66In stock
• 5x5x4 ECT-32 Kraft Corrugated Boxes - Standard Strength Shipping, 25-Pack
  $9.71In stock
• 8x6x3 ECT-32 Kraft Corrugated Boxes - Shallow Depth Shipping, Bundle of 25
  $9.78In stock
• 8x6x4 ECT-32 Kraft Corrugated Boxes - Bundle of 25
  $9.78In stock
• 6x6x5 ECT-32 Kraft Corrugated Boxes - Reliable Strength, 25-Pack Bundle
  $9.78In stock
• 6x6x4 Multi-Depth Corrugated Boxes ECT-32 Kraft - Adjustable, 25-Pack
  $9.81In stock

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