400 oz Gold Bar
The 400 oz gold bar is the globally recognized institutional standard for physical gold used in professional custody, settlement, and reserve management.
Weighing approximately 12.4 kilograms, it forms the core unit of trade among central banks, bullion banks, and accredited vault operators within the international bullion market.
Definition and Purpose
A 400 oz gold bar, also known as a “Good Delivery” bar, conforms to the technical and quality requirements set by the London Bullion Market Association (LBMA).
It is the largest and most efficient format for institutional holdings, designed to minimize storage costs, simplify settlement, and ensure liquidity across borders.
These bars are not typically traded by retail investors — they are the foundation of wholesale gold transactions, interbank settlements, and national reserve management.
Physical Specifications
| Parameter | Specification |
|---|---|
| Nominal Weight | 400 troy ounces (approx. 12.4 kg) |
| Accepted Range | 350–430 troy ounces |
| Minimum Fineness | 995.0 parts per thousand (99.5%) |
| Typical Purity | 999.9 parts per thousand |
| Form | Cast trapezoidal bar |
| Dimensions | Length: 210–290 mm · Width: 55–85 mm · Height: 25–45 mm |
| Markings | Serial number, refiner’s hallmark, assay stamp, fineness, and year of production |
Every bar carries a unique serial number recorded by the refiner, custodian, and vault operator, ensuring complete traceability through its lifecycle.
Manufacturing Process
Production is carried out exclusively by LBMA-accredited refineries under the Good Delivery Rules.
The process involves:
- Melting and refining gold doré or recycled feedstock to achieve required purity;
- Casting the molten gold into pre-defined molds;
- Cooling and surface finishing to maintain correct weight and markings;
- Weighing and stamping, assigning a unique serial number and fineness mark;
- Registration with both the refinery’s internal system and LBMA referee laboratory.
Assay verification ensures compliance with LBMA standards before bars are accepted into the professional custody system.
Custody and Settlement
Within the global custody network, 400 oz gold bars are the primary settlement unit between institutions.
They are stored in LBMA-accredited vaults, where each bar is logged in detailed barlists used for reconciliation, audit, and insurance reporting.
Ownership transfers occur through book-entry settlement within the London Precious Metals Clearing Limited (LPMCL) system, avoiding physical movement while maintaining full traceability.
If required, vault-to-vault transfer allows physical relocation without breaking the chain of custody.
All holdings are subject to independent vault audits, confirming that barlists match actual inventories, ensuring the integrity of reported reserves.
Institutional Applications
400 oz gold bars serve multiple institutional functions:
- Central bank reserves — stored as part of national monetary assets;
- Interbank settlement — used for transfers between clearing members;
- Collateralization — pledged against derivatives or lending exposures;
- ETF and fund backing — forming the physical foundation of gold-backed instruments;
- Refining feedstock — recast into kilobars or investment bars for retail markets.
Their standardized format allows precise valuation and efficient liquidity conversion in all major bullion hubs.
Compliance and Integrity
Each 400 oz bar must originate from an LBMA Good Delivery refinery and meet the Responsible Gold Guidance (RGG) for ethical sourcing.
Custodians and vaults maintain compliance with FATF AML/KYC and OECD Due Diligence standards to prevent conflict-related or illicit material from entering the system.
Regular audits, insurance verification, and barlist reconciliation confirm the ongoing authenticity and quality of all 400 oz holdings within institutional custody.
Institutional Role
The 400 oz gold bar is the operational cornerstone of the global gold market.
It enables consistent valuation, transparent reporting, and efficient settlement across all financial centers.
By standardizing form, weight, and purity, it ensures that gold functions as a uniform and verifiable reserve asset — the essential link between physical bullion and institutional finance.