A small quantity is the maximum amount of a specific hazardous material that when transported by domestic surface transportation is not subject to any DOT requirements (e.g., packaging, marking, labeling, etc.) other than those in 49 CFR 173.4. Not every hazardous material is eligible to be shipped as a small quantity. Additionally, for Postal Service purposes, Class 1, Class 2, Division 6.2, and Class 7 materials are not permitted to be sent as a small quantity.
The small quantity provision is applicable to domestic mail only, and its use is prohibited for international shipments or APO/FPO/DPO mail. The small quantity provision can be used only for domestic surface transportation (highway or rail).
Hazardous materials in Class 3, Division 4.1, Division 4.2 (Packing Groups II and III only), Division 4.3 (Packing Groups II and III only), Division 5.1, Division 5.2, Division 6.1 (Packing Group III only), Class 8, and Class 9 are eligible to be sent in domestic mail under the small quantity provision, via a USPS ground product (e.g. USPS Retail Ground, Parcel Select, Parcel Select Lightweight) only when each primary receptacle is limited to the following quantity, as applicable:
- 30 ml (1 oz.) or less for liquids.
- 30 g (1 oz.) or less for solids.
Materials identified in Appendix A as prohibited under column E, USPS Mailability, are ineligible for mailing under the small quantity provision without regard to their hazard class, division, or packing group.
Hazardous materials eligible to be shipped under the small quantity provision permitted in 49 CFR and 336.2 must be prepared following Packaging Instruction 10A in Appendix C. Each mailpiece that qualifies to be sent under the small quantity provision must be clearly marked on the address side with the following words: “This package conforms to 49 CFR 173.4 for domestic highway or rail transport only.”