Shipments destined for U.S. addresses may qualify for special pricing with our partner carrier USPS based on their size. This ‘cubic pricing’ is an additional discount that is often applied to heavier packages which have smaller volumes. 

Cubic shipping is a cost-effective option that helps you save with pricing that is not based on weight. Postage costs are determined by the shipment’s cubic dimensions and zone instead. 

How to calculate cubic volume

To calculate the cubic volume of your shipment, please use the following formula:

Cubic feet = (L X W X H) / 1,728

L, W, H in inches (rounded down to the nearest 1/4 or 0.25 inch).

For example, the cubic volume of a shipment with dimensions 6, 5 ¾, 6 ¼ inches would be calculated as below:

(6" x 5-3/4" x 6-1/4")/1728 = 0.125"

Does my shipment qualify for a cubic discount?

To qualify for cubic pricing, the following criteria must be met:

  • Package type must be parcel and dimensions must be provided 
  • Shipments must weigh 20 lbs or less
  • Shipments must measure 0.50 cubic foot or less
  • The longest dimension may not exceed 18 inches
  • The shipment must not be a roll or tube

For thick envelope (SoftPack) package types, there are additional requirements:

  • Packaging must be flexible and fit tight to the contents (e.g. poly mailers, plastic or vinyl envelopes)
  • Dimensions must be provided and taken prior to packaging with the envelope
  • The shortest dimension may not exceed 2 inches
  • The sum of the two longest dimensions may not exceed 36 inches

Chit Chats will automatically provide you with the cubic discount for your postage based on the weight and dimensions of your USPS or Chit Chats U.S. Tracked parcels.

Discounts are applied for the following tiers based on cubic volume. 

  • Parcels measuring up to .10 cubic foot
  • Parcels between .10 up and .20 cubic foot
  • Parcels between .20 up and .30 cubic foot
  • Parcels between .30 up and .40 cubic foot
  • Parcels between .40 up and .50 cubic foot

This means that for two parcels 4 lbs and 15 lbs, each with a cubic volume between 0.30 and 0.4 cubic feet will receive the same cubic discount.