Written by: Timur Lesov

September 12, 2025

Updated on August 18, 2025

Key Takeaways

• Large Flat Rate Box: $24.75 retail (up to 70 lb) regardless of weight or distance.
• Small Flat Rate Box: $10.40 retail (up to 70 lb) regardless of weight or distance.
• Flat Rate Envelopes range from $9.85 to $10.60 retail.
• Commercial (online) rates are typically 15–20% lower than retail.

1. What Is USPS Flat Rate Shipping?

USPS Priority Mail Flat Rate is a shipping service that lets you send any item weighing up to 70 lb in USPS-provided, standardized packaging for a single price, regardless of the ship-to destination within the U.S. Flat rate pricing simplifies shipping costs, particularly for heavy items traveling long distances.

Advantages

• One fixed price for any zone (1–9).
• Flat Rate packaging is provided free of charge.
• Includes USPS Tracking® and up to $100 of insurance.
• Delivery in 1–3 business days.

When to Use Flat Rate

• Shipping heavy items (> 20 lb) long distances.
• Avoiding variable weight-and-zone pricing if your own packaging would cost more.
• Sending multiple small heavy items that fit into the box dimensions.

2. Flat Rate Packaging Options & Retail Prices

Below are the primary Flat Rate packaging types, their dimensions, and retail shipping prices.

* APO/FPO Large Box retail price is the same as standard large box; commercial base price includes a military discount.

3. Breakdown of “How Much to Ship” Queries

3.1 How Much to Ship a Large Flat Rate Box?

• Retail rate: $24.75
• Commercial (online) rate: $19.51
• Weight up to 70 lb and any domestic ZIP code.
• Box dimensions: 12 1⁄4″ × 12 1⁄4″ × 6″.

3.2 How Much Is a Large Flat Rate Shipping Box?

• Price to purchase: free from Post Office or USPS.com.
• Shipping cost (retail): $24.75.

3.3 How Much Are Flat Rate Shipping Boxes?

• All Flat Rate boxes and envelopes are provided at no cost.
• Shipping cost varies by package size as shown above.

3.4 How Much to Ship a Small Flat Rate Box USPS?

• Retail rate: $10.40
• Commercial rate: $8.51
• Dimensions: 8 11⁄16″ × 5 7⁄16″ × 1 3⁄4″.
• Weight up to 70 lb and any domestic destination.

3.5 How Much Is It to Ship Large Flat Rate Box / Small Flat Rate Box?

• Large: $24.75 retail, $19.51 commercial.
• Small: $10.40 retail, $8.51 commercial.

4. Commercial vs. Retail Rates

• Retail Rate: price paid at the Post Office counter or via USPS.com retail checkout.
• Commercial Rate: discounted rates available via Click-N-Ship®, postage meters, or business accounts-typically 15–20% off retail.
• Businesses and frequent shippers should use online postage tools to access lower rates.

5. Ordering Flat Rate Boxes

• USPS.com: free home delivery of boxes; ordering minimums apply (e.g., 10-pack).
• Post Office: pick up boxes free at most locations.
• Third-party providers: often include commercial pricing and integration with shipping software.

6. Tips to Maximize Savings

1. Use Flat Rate only for heavy, long-distance shipments.
2. For lighter or local packages, compare weight-based Priority Mail rates which may be cheaper.
3. Leverage commercial rates via online postage platforms to save up to 20%.
4. Pack items efficiently to fit the smallest possible Flat Rate packaging.

7. Conclusion

USPS Flat Rate Boxes provide predictable, zone-independent pricing for packages up to 70 lb. For a large Flat Rate Box, expect to pay $24.75 retail or $19.51 commercial; for a small Flat Rate Box, $10.40 retail or $8.51 commercial. These rates simplify shipping heavy items over long distances, and free packaging makes them a convenient option for both consumers and businesses.

Timur Lesov

Eco-freak, nerd, and green technology fanatic. I’m in favor of making eco-friendly living simple as well. I graduated from Berkeley in 2017. Studied environmental science and all things sustainability related. I create content and share simple tips for greening your everyday life. I think even small changes can make a huge difference and we can build a cleaner and more sustainable future.