Net Weight, Gross Weight and VGM Are Different Shipping Records
A packing list can show the net and gross weight of every crate while the ocean container still has no verified gross mass. The figures answer different questions. Item net weight describes the goods within a stated boundary. Package gross weight adds the packaging included in that package. Verified Gross Mass, or VGM, applies to the packed container and must be obtained through an allowed method, documented by the responsible shipper, and provided in time for the vessel stowage plan.
The distinction matters for heavy spare parts because one order may move through several weight records. Individual parts are weighed or listed, crates receive gross weights, bracing is added during loading, and the actual container contributes its tare mass. Copying one subtotal into a VGM field can leave part of that physical system outside the declaration.
This article explains the record and handoff. It does not calculate freight chargeable weight, set customs values, approve shipping marks or replace the current instructions of the carrier, terminal and competent authority.
Distinguish VGM from cargo weight
Start by naming the object each number describes. A part's net weight may exclude its bag, skid or crate. A crate's gross weight normally includes the crate and the goods inside it, but it still does not include another crate, container tare, or bracing added elsewhere. A cargo total may combine packages yet use a different boundary from the final packed container.
The International Maritime Organization's VGM guidance describes two routes to the verified gross mass of a packed container. It also makes the loading boundary clear: VGM is a condition for loading under the applicable SOLAS rules, but having a VGM does not itself entitle a container to be loaded. The master retains the relevant discretion.
For a parts team, the useful question is not “Do we have a weight?” It is “Which physical items and materials does this number include?” Record cargo items, inner and outer packaging, pallets, dunnage, bracing or securing material, and the tare of the actual container. If one of those categories is handled in another document, link that document and version rather than assuming it was included.
The diagram is a boundary check, not a calculation certificate. A package weight can be fully supported and still be only one input to the container record. Likewise, an invoice quantity or nominal catalogue mass cannot replace the actual evidence required by the chosen VGM method.
Confirm the permitted weighing method
Under the IMO explanation, Method 1 weighs the packed container. Method 2 weighs all packages and cargo items, including pallets, dunnage and other securing material, and adds the container tare. Method 2 must use a certified method approved by the competent authority of the state where packing was completed. That local approval condition is why a generic spreadsheet cannot declare itself compliant.
For Method 1, identify the packed container, the weighing equipment or facility record, the date and the result. The container should be in the same packed state represented by the declaration. If a crate, brace or other material is added afterward, the prior result no longer describes the final physical state and must be reconciled under the applicable process.
For Method 2, trace every component of the sum. Use the actual package records for the order, include separate pallets and securing materials, and connect the tare to the actual container number. A tare copied from an unrelated container or an earlier booking creates a conflict. Do not average it, select the more convenient value or leave the container identity implicit.
The method record should also state the units. Mixing kilograms, pounds or tonnes without an explicit conversion can produce a plausible-looking total that is wrong. Keep the original values and units, record any conversion once, and retain the person or system that performed it. If a value is estimated rather than measured or documented, label it as an estimate and do not present the result as a completed VGM.
National implementation can add details about approved processes and enforcement. Use the competent authority for the state where packing occurs, then check the carrier and terminal instructions for submission. An authority's rules for one country do not automatically govern a container packed elsewhere.
Build the traceable VGM record
A defensible record connects the number to one booking and one physical container. Capture the booking reference, container number, seal where applicable, packing location, completion date, selected method, source measurements, tare source, units, calculation or weighing result, responsible shipper identity, authorized signer and declaration version.
The legal definition of the shipper for this requirement is tied to the person or entity named in the bill of lading, sea waybill or equivalent transport document and the contract of carriage. Operational teams should not assign responsibility from job title alone. Confirm who is acting as shipper for the actual movement and who is authorized to sign or submit on that party's behalf.
The Digital Container Shipping Association's VGM overview describes the declaration as information exchanged among the shipping parties and emphasizes current updates and corrections. Its API standard is one industry implementation. The article does not require that API; the transferable lesson is to keep the latest declaration, acknowledgement and correction connected to the same container and booking.
The following table is an illustrative handoff record. It shows how a normal file differs from missing or conflicting evidence. It does not produce or approve a VGM.
| Case | Container and method | Mass evidence included | Responsibility and submission | Status |
|---|---|---|---|---|
| Normal record | Actual container ID recorded; approved Method 2 process named | All package records, pallets, dunnage, securing material and matched container tare reconcile in one unit system | Responsible shipper and authorized signer recorded; current declaration acknowledged for the booking | Ready for the authorized shipping review; not a loading guarantee |
| Missing input | Container ID known; tare source absent | Crate gross weights listed, but no record for added bracing and no supported container tare | Signer and submission channel not yet confirmed | Unresolved—do not convert the cargo subtotal into VGM |
| Conflict after change | Declaration names one container; packing record was moved to another | A late crate and new securing material appear after the recorded calculation | Original acknowledgement exists, but no amended declaration is recorded | Hold and reconcile the actual packed state, method and updated submission |
Keep unresolved fields explicit. A blank tare, unidentified signer or absent acknowledgement is not zero and is not evidence that the step was unnecessary. Name the owner of the missing input and the latest time at which the record can still be corrected under the actual booking.
Submit and reconcile changes before the cutoff
The IMO requires VGM information to reach the master or representative and the terminal representative sufficiently in advance for the stowage plan. It does not publish one universal clock time for every booking. The applicable cutoff comes from the carrier or terminal and can vary with the service, port and voyage. Record the source, time zone and access date instead of turning one shipment's deadline into evergreen advice.
Submission is not complete merely because someone sent an email or entered a portal field. Retain the declaration version, channel, time, sender and acknowledgement or current status. If the carrier or terminal reports a mismatch, connect the correction to the original record rather than creating an untraceable second number.
Use one version sequence across the handoff. For example, a packing team may issue a first record after loading, then discover that the container number was transposed or that additional securing timber changed the mass. The correction should identify what changed, preserve the superseded value, and show which version the carrier or terminal most recently acknowledged. Deleting the first entry can make two parties appear to agree when they are actually working from different numbers. A clear superseded status keeps the history without allowing an old value to remain operational.
Before the cutoff, compare the acknowledgement against the source record instead of checking only that a response exists. Verify the booking, container number, mass, unit, method and declaration version. If the response does not expose every field, retain enough submission evidence to connect it to the exact message or portal entry. An acknowledgement confirms receipt within that channel; it does not repair an unsupported input or authorize a different physical container.
Reopen the VGM check whenever the physical packed state changes. Typical triggers include a substituted container, changed tare, added or removed crate, replaced pallet, extra blocking or bracing, repacking after inspection, or a corrected source measurement. Determine whether the selected method must be repeated or recalculated, obtain the authorized signature or equivalent record, and submit the current declaration before the applicable cutoff.
Also reconcile the supporting documents. The packing list may need a revised package count or gross weight, while the shipping mark may need a separately controlled update. Those records must agree on shared identifiers, but none should be described as the VGM simply because it contains a weight field.
The bulk undercarriage parts sourcing guide provides wider order context. For the container handoff itself, the stopping rule is narrower: the actual container, permitted method, complete mass boundary, responsible shipper, current declaration and booking-specific submission status must all be traceable. Anything missing or inconsistent stays unresolved until the authorized shipping parties close it.