The chart below shows the USPS First-Class Mail and First-Class Package service item size and weight restrictions.
The Predefined Package names are drawn from the EasyPost API, so you can better reference how each Predefined Package matches up dimensionally.
Predefined Package Name | Dimensions | Weight |
---|---|---|
Card |
| Must be a flat surface |
Letter |
| Maximum weight is 3.5 oz. |
Flat |
| Maximum weight is 13 oz. |
Parcel | Maximum size is 108" in combined length and girth (distance around the thickest part). First-Class™ Package Service packages cannot exceed 22" x 18" x 15". | Maximum weight for Priority Mail Express, Priority Mail, Library Mail, or Media Mail® is 70 lbs. First-Class™ Package Service packages must weigh less than 16 oz. |
FlatRateEnvelope | 12 ½" x 9 ½" |
|
FlatRateLegalEnvelope | 15" x 9 ½" |
|
FlatRatePaddedEnvelope | 12 ½" x 9 ½" |
|
FlatRateGiftCardEnvelope | 10" x 7" |
|
FlatRateWindowEnvelope | 10" x 5" |
|
FlatRateCardboardEnvelope | 12 ½" x 9 ½" |
|
SmallFlatRateEnvelope | 12 ½" x 9 ½" |
|
SmallFlatRateBox | 8 ⅝" x 5 ⅜" x 1 ⅝" | Maximum weight is 70 lbs. |
MediumFlatRateBox | 11" x 8 ½" x 5 ½" | Maximum weight is 70 lbs. |
LargeFlatRateBox | 12" x 12" x 5 ½" | Maximum weight is 70 lbs. |
SoftPack | The longest dimension may not exceed 18 inches. Cubic rating will be applied using Length and Width only. See more details on the USPS Cubic Pricing page. | Maximum weight is 20 lbs. |
Ready to start shipping your USPS packages? EasyPost offers Commercial Pricing to all customers, regardless of volume. Discover how much you can save compared to retail rates today with our USPS Rate Chart.