USPS: Cubic Rates in Postsale
About Cubic Rates and how they are calculated
In This Article
USPS Cubic Rates are a great way to save on postage costs when shipping small, heavy packages since the rate is based upon the volume of the package instead of the weight. Cubic rates are available for rectangular/nonrectangular packages and Soft Pack/padded envelopes when shipping with:
- Priority Mail®
- USPS Ground Advantage®
The good news is that Postsale automatically calculates the cubic rate and applies it to your shipment when the cubic rate is cheaper than the weight based rate.
Continue reading this article if you would like to explore how cubic rates are calculated.
How Cubic Pricing is Calculated
Cubic rates are based upon the volume of the package and not the weight. The calculated volume of the package determines the pricing tier for the package. The cubic tier is determined based upon whether the package is:
- Rectangular/nonrectangular
- Soft Pack/padded envelopes
Select the correct tab to learn more about how cubic rates are calculated:
Rectangular & Nonrectangular Parcels
Calculate the volume of the parcel:
- Measure in inches the length, width, and height of the parcel at each dimension's maximum point.
- Round each measurement down to the nearest 0.25 inch. For example: 7.25" x 5.75" x 5.25"
- Round each measurement down to the nearest 0.25 inch. For example: 7.25" x 5.75" x 5.25"
- Use the following formula to calculate the cubic feet:
- (Length x Width x Height) / 1,728 = cubic feet
- For example: 7.25" x 5.75" x 5.25" = 218.85 divided by 1,728 = 0.13 cubic feet
Based upon the calculated cubic feet and the service used, the parcel is assigned to the correct tier.
Soft Pack & Padded Envelopes
When shipping with Soft Packs or padded envelopes:
- The cubic tier is based on the length and width of the flat prior to being loaded with items.
- Pleated or expandable mailpieces should be calculated using the rectangular & non rectangular calculation method.
- Measure the length and width of the flat in inches.
- Round each measurement down to the nearest 0.25 inch. For example: 10" x 10.75"
- Round each measurement down to the nearest 0.25 inch. For example: 10" x 10.75"
- Add the two dimensions together. Then, based upon the service being used, determine the correct pricing tier using the Cubic Rate Tiers section below.
- For example: 10" + 10.75" = 20.75"
Cubic Rate Tiers
Tiers are assigned based on the service being used, whether the parcel is rectangular/nonrectangular or a Soft Pack/padded envelope, and the calculated measurement of the parcel. Select the correct service tab to view Cubic Rate requirements and tier tables.
Priority Mail®
Rectangular & Nonrectangular
USPS Priority Mail® parcels meeting the following requirements qualify for Cubic Rates:
- Weighs less than 20 pounds
- Longest dimension is not greater than 18 inches
- Measures 0.50 cubic feet or less
| Cubic Price Tier | Mailpiece Measuring… | Calculated Cubic Foot |
|---|---|---|
| 0.1 | up to and including | .10 |
| 0.2 | more than | .10 up to and including .20 |
| 0.3 | more than | .20 up to and including .30 |
| 0.4 | more than | .30 up to and including .40 |
| 0.5 | more than | .40 up to and including .50 |
Soft Pack & Padded Envelope
USPS Priority Mail® Soft Pack & padded envelopes meeting the following requirements qualify for Cubic Rates:
- Weighs 20 pounds or less
- Cannot be in rolls or tubes
- Longest dimension cannot exceed 18 inches
| Cubic Price Tier | Mailpiece Measuring… | Length + Width |
|---|---|---|
| 0.1 | from | 0" up to 21" |
| 0.2 | more than | 21" up to 27" |
| 0.3 | more than | 27" up to 31" |
| 0.4 | more than | 31" up to 34" |
| 0.5 | more than | 34" up to 36" |
Ground Advantage®
Rectangular & Nonrectangular
USPS Ground Advantage® parcels meeting the following requirements qualify for Cubic Rates:
- Weighs less than 20 pounds
- Longest dimension is not greater than 18 inches
- Measures 0.50 cubic feet or less
| Cubic Price Tier | Mailpiece Measuring… | Calculated Cubic Foot |
|---|---|---|
| 0.1 | up to and including | .10 |
| 0.2 | more than | .10 up to and including .20 |
| 0.3 | more than | .20 up to and including .30 |
| 0.4 | more than | .30 up to and including .40 |
| 0.5 | more than | .40 up to and including .50 |
| 0.6 | more than | .50 up to and including .60 |
| 0.7 | more than | .60 up to and including .70 |
| 0.8 | more than | .70 up to and including .80 |
| 0.9 | more than | .80 up to and including .90 |
| 1 | more than | .90 up to and including 1.00 |
Soft Pack & Padded Envelope
USPS Ground Advantage® Soft Pack & padded envelopes meeting the following requirements qualify for Cubic Rates:
- Weighs 20 pounds or less
- Cannot be in rolls or tubes
- Longest dimension cannot exceed 18 inches
| Cubic Price Tier | Mailpiece Measuring… | Length + Width |
|---|---|---|
| 0.1 | from | 0" up to 16" |
| 0.2 | more than | 16" up to 21" |
| 0.3 | more than | 21" up to 24" |
| 0.4 | more than | 24" up to 26" |
| 0.5 | more than | 26" up to 28" |
| 0.6 | more than | 28" up to 30" |
| 0.7 | more than | 30" up to 32" |
| 0.8 | more than | 32" up to 34" |
| 0.9 | more than | 34" up to 35" |
| 1 | more than | 35" up to 36" |