USPS Priority Mail: Regional Rates vs Flat Rate Packages

In this guide, we compare specific USPS Priority Mail services: Regional Rate boxes and Flat Rate packaging. To make a comparison using this guide, you will need an accurate weight of the package you want to ship as well as know the size of the product and packaging it will be shipped in. Use this guide if your packages meet the following requirements:

• Weigh less than 70 lbs.

If your packages exceed this - compare other Priority Mail options.

Comparing Regional Rate boxes and Flat Rate packaging

Package Size

With either Regional Rate boxes or Flat Rate boxes and envelopes, the USPS requires using specially marked boxes. Contents must fit comfortably and packing must be sealed without any bulging. Learn more about USPS domestic package dimensions.

If your products will fit into Flat Rate envelopes or Small boxes, USPS Flat Rate will always yield a lower rate than USPS Regional Rate boxes. This is across all weights (up to 70lbs) and zones.

Package Type

The key restriction of Regional Rate boxes is that their contents may not exceed 20 lbs, depending on the box option. In contrast, Flat Rate services support content up to 70 lbs (assuming your products will fit in the box).

Regional Rate boxes and Flat Rate boxes are not interchangeable. 

Example: You select the Flat Rate Padded Envelope creating the label. You must use this label with the matching USPS package type. 

Zone

Flat Rate boxes (Medium and Large) are a better option when shipping further (higher zone). Regional Rate boxes (A and B) will offer the lower price for shipping between closer destinations (lower zone). Learn more about USPS zones.

Detailed Service Comparisons

The tables below provide a visual summary of when it is best to use a Regional Rate or Flat Rate package, based on weight and zone.

To simplify the data, we use a color and letter code to indicate the best packaging. Please keep in mind that the services listed are only the best value when your products will fit into the defined package dimensions. Use the legend below to read the following charts.

Regional Rate Box A - vs - all Flat Rate packaging

If your contents fit in the Flat Rate Small box or envelopes, use these packaging options instead of Regional Rate.

Regional Rate Box B - vs - all Flat Rate packaging

If you are shipping items across the country, to Zone 6 or higher, Flat Rate Medium and Large boxes will be a better value than Regional Rate Box B.

When your parcels weigh over 20 lbs, use Flat Rate boxes.

Regional Rate Box A - vs - Medium and Large Flat Rate boxes

When your products fit in either Regional Rate Box A or Flat Rate Medium box, you will get a better rate with Regional Rate for most destinations. Learn how to assign USPS Regional Rate Boxes to shipments within specific zones.

If your parcels weigh over 15 lbs, use Flat Rate boxes.

Regional Rate Box B - vs - Medium and Large Flat Rate boxes

If you are shipping items across the country, to Zone 6 or higher, Flat Rate Medium and Large boxes will be a better value than Regional Rate Box B. Learn how to assign USPS Regional Rate Boxes to shipments within specific zones.

When your parcels weigh over 20 lbs, use Flat Rate boxes.

Continue Comparing Regional Rate boxes or Flat Rate packaging

Consider the conclusions that you have drawn about your shipments and whether or not Regional Rate or Flat Rate is the better value. Then use this information to continuing comparing the best of the two with your other Priority Mail service options:

Regional Rate

Is Regional Rate a good fit for your shipments? If so, take a look at these other rate comparison guides:

• Regional Rate versus Flat Rate Green (dimensional)
• Regional Rate versus Weight-based rates

Flat Rate

Is Flat Rate a good fit for your shipments? If so, take a look at these other rate comparison guides:

• Flat Rate packages versus Flat Rate Green (dimensional)
• Flat Rate packages versus Weight-based rates