Packaging Reference Library · Wall Charts

Box Maker's Certificate Decoder

How to read each line of the Box Maker's Certificate printed on a corrugated box flap, for both the Edge Crush Test and the Mullen burst versions.

Ref PK-0210NMFC Item 222UFC Rule 41

Draft, open for review. Check every value against the governing standard and the manufacturer’s data before use.

What it is

The Box Maker's Certificate (BMC) is the round or square stamp printed on the outside of a corrugated box, usually on a bottom flap. It states that the box meets the construction rules of the applicable freight classification. The rules are NMFC Item 222 for motor carriers and UFC Rule 41 for rail. A box can be certified by Edge Crush Test (ECT) or by Bursting Test (Mullen), and the certificate shows which.

How to read it

Find the stamp on the bottom flap or a side panel.
Read the test type: Edge Crush Test or Bursting Test.
Read the rating and the units.
Read the size limit and the gross weight limit.
Read the box maker's name and city.

Certificate lines

Line on the certificate	What it means	Appears on
Box maker name and location	Who made the box and where	Both
Single wall, double wall or triple wall	Board construction	Both, often
Edge Crush Test (ECT), lbs per inch width	Edge crush rating, for example 32	ECT certificate
Bursting Test, lbs per sq inch	Burst rating, for example 200	Burst certificate
Minimum combined weight of facings, lbs per M sq ft	Total weight of the liners per thousand square feet	Burst certificate
Size limit, inches	Largest allowed sum of outside length, width and depth	Both
Gross weight limit, lbs	Most the packed box may weigh under the rule	Both
Statement of compliance	Box meets the applicable freight classification	Both

Key points

The certificate applies to the box as made. Cutting it down, re-taping it or reusing it after damage can void the basis for it.
Size limit is the total of the three outside dimensions, not the longest one.
Packing a box past its gross weight limit means it no longer meets the certificate.
Parcel carriers have their own packaging rules. A BMC helps but does not replace them.
Carrier classification rules change from time to time. Check the current NMFC and the carrier's tariff before relying on a certificate.

Common mistakes

Reading the ECT number as pounds the box can hold.
Comparing an ECT certificate and a burst certificate number for number.
Shipping a heavier load than the gross weight limit because the box "looks strong."
Assuming a box with no certificate is weaker. It may just be uncertified.
Ignoring the size limit on large boxes.

Governing standards: NMFC Item 222 (motor carrier packaging); UFC Rule 41 (rail packaging); TAPPI T 811 and T 810 (test methods behind the ratings).

Reference only. Verify against the current governing code or standard, the manufacturer's data and the project documents before use. Apps for Distributors disclaims liability arising from reliance on this reference.

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