A buyer who has resolved to hold physical gold still has to choose the format the holding will live in, and the choice is more consequential than the weight difference suggests. A 400 oz Good Delivery bar acquires metal at the lowest premium over spot and sits inside the deepest institutional pool in the market — but only for as long as the bar stays inside that pool. A 1 kg bar costs more per ounce at acquisition and circulates across a far wider counterparty universe, including the secondary channels through which most physical gold actually changes hands. The tradeoff runs through premium, exit behavior, custody placement, and divisibility, and a holding of any size will land on one format, the other, or a deliberate combination of both.
1. The two reference formats
Before the operational differences, the two bars themselves. Both formats originate at accredited refineries — in Golden Ark Reserve’s supply, Heraeus Precious Metals and Argor-Heraeus SA — and both carry refiner mark, serial number, and assay. What separates them is weight class, casting method, and the standard the format was designed to meet.
1.1. The 400 oz Good Delivery bar
Among physical gold formats, the 400 oz bar serves as the institutional reference and the unit in which the LBMA wholesale market clears. Production is by pour: molten gold flows into a mold and cools as a cast bar. Nominal weight is 400 troy ounces — roughly 12.4 kilograms. The format runs on a tolerance band. LBMA Good Delivery specifies an acceptable gold content of 350 to 430 fine troy ounces, with the bar’s actual weight stamped to the nearest 0.025 troy ounce. Minimum fineness is 995.0 parts per thousand fine gold. Each bar carries the refiner’s stamp, a serial number, the year of manufacture, and the assay mark, and the refiner itself must hold current LBMA Good Delivery accreditation for the bar to enter the chain. Format detail and order parameters live on the 400 oz bar page. Argor-Heraeus has held LBMA Good Delivery referee status for gold since 2004, and Heraeus is similarly listed on the LBMA Good Delivery roster — both refineries produce 400 oz bars to this specification.
A 400 oz bar is built once, marked once, and assayed once. Everything that follows treats that work as authoritative.
1.2. The 1 kg cast and minted bar
Below the wholesale clearing tier, the 1 kg bar is the institutional-grade format. Weight is fixed at exactly 1,000 grams — 32.15 troy ounces — with no tolerance band, which is itself a structural difference from the 400 oz format. Minimum fineness is 999.9 parts per thousand for investment-grade 1 kg bars, higher than the 400 oz floor. The format exists in two production methods. Cast 1 kg bars are produced by the same pour-and-cool process as 400 oz bars, with a rougher surface finish and lower fabrication cost. Minted 1 kg bars are struck from rolled blanks, finished to a polished face, and typically sealed in tamper-evident assay cards that bind the bar to its certificate. Both methods carry refiner mark, serial number, fineness, and weight; the assay card or certificate accompanies minted bars as a single unit.
Although refinery accreditation matters at the 1 kg tier as well, the operational standard the bar lives under is different from Good Delivery. Section 3 takes that up.
Detailed format specification and order parameters live on the 1 kg bar page.
2. Specification and capital exposure at a glance
Read in parallel, the format-level parameters separate cleanly along weight class, fabrication regime, governing standard, and the capital each bar represents in a single position.
| Parameter | 400 oz Good Delivery bar | 1 kg bar |
|---|---|---|
| Nominal weight | 400 troy oz (~12.4 kg) | 1,000 g (32.15 troy oz) |
| Weight tolerance | 350–430 fine troy oz (band) | Fixed, no tolerance |
| Minimum fineness | 995.0 / 1,000 | 999.9 / 1,000 |
| Production method | Cast | Cast or minted |
| Approximate metal value per bar | ~400 × spot | ~32.15 × spot |
| Indicative capital exposure per bar at $4,700/oz reference | ~$1.88M | ~$151K |
| Premium over spot (typical range) | Low tens of cents per oz | Several dollars per oz; minted higher than cast |
| Governing standard | LBMA Good Delivery (format + chain-of-integrity custody) | Refiner accreditation; not part of GDL chain |
| Minimum holding increment | One bar (~12.4 kg) | One bar (1 kg) |
| Vault placement | LBMA-approved facility required to retain GDL status | LBMA-approved, free-zone, or private allocated vault |
Spot moves continuously; capital-exposure figures above are illustrative at a stated reference price and recalculate against live spot at the moment of order.
3. LBMA Good Delivery and the chain of integrity
Beyond weight class, the 400 oz and 1 kg formats sit in structurally different relationships to the standard that governs wholesale physical gold, and that relationship drives almost every operational difference downstream.
LBMA Good Delivery is a specification for 400 oz bars and a custody protocol for the bars produced under it. A bar enters the chain when cast to specification by an accredited refiner. It stays in the chain through continuous custody at LBMA-approved vaults under recognized counterparties. Movement between approved vaults preserves the chain. Removal from the network — physical delivery to a buyer, placement in a non-approved facility, any break in documented custody — takes the bar out of the chain. Re-entry requires re-assay or re-refining by an accredited refiner before the bar can clear in the wholesale market again, and the cost is borne by whoever wants to put it back.
The 1 kg format sits outside this chain. A 1 kg bar from an LBMA-accredited refiner carries refinery-level provenance — the same refiner mark, the same assay, the same serial — but the format itself is not Good Delivery and the bar does not move through approved-vault custody as its operating mode. Its acceptance in any given transaction rests on the refiner’s accreditation and the bar’s documentation, not on chain-of-integrity custody. That distinction is structural rather than evaluative: 1 kg bars are designed for a different circulation pattern, and the absence of GDL custody is what enables that pattern.
Why 400 oz became the institutional standard in the first place — the historical and market-structure reasons the wholesale tier consolidated around this format — is treated separately in Why Institutions Standardize on 400 oz LBMA Bars. Sections 4, 5, and 6 below take the consequences of the GDL distinction in turn: what it does to premium, what it does to exit, and what it does to physical handling.
4. Premium structure and effective acquisition cost
Physical gold transacts at spot plus a premium, and the premium is where the two formats separate at the buy side. The metal content per ounce is identical; what differs is the cost of turning refined metal into a finished, market-acceptable bar of a given size, and that cost does not scale linearly with weight.
Among physical gold formats, the 400 oz Good Delivery bar carries the lowest premium over spot. Fabrication is a single pour of approximately 12.4 kilograms of metal into a mold, with weight and assay stamped on the cooled bar: one cast, one set of marks, one assay event spread across 400 troy ounces. Premiums in wholesale lots typically run in the low tens of cents per ounce, though the exact figure moves with refining capacity, refinery order books, and dealer inventory. The format is the cheapest way to acquire allocated physical metal per ounce. That pricing is itself a function of the wholesale tier the bar is built for.
The 1 kg bar carries a higher premium, and the gap widens further between cast and minted production. Cast 1 kg bars sit closer to the 400 oz tier on a per-ounce basis because the production method is the same — one pour, one set of marks — applied to a smaller weight; the fabrication cost is spread across roughly thirty-two ounces rather than four hundred. Minted 1 kg bars add the cost of rolling blanks, striking the face, finishing, and sealing the bar into an assay card, which lifts the per-ounce premium meaningfully above cast. Across the 1 kg tier, premiums typically run several dollars per ounce above spot rather than cents, with the range depending on refiner, production method, and order size.
What the premium gap funds is not metal but market access. The 400 oz premium reflects the cost of producing a bar that clears in the wholesale tier; the 1 kg premium reflects the cost of producing a bar that circulates in the wider market discussed in section 5. Live spot reference and the OTC/LBMA pricing mechanics under which premiums are quoted are on the gold price page. Premium is recoverable to the extent that the format the buyer paid into is the format the buyer can sell back into.
5. Secondary-market depth and exit liquidity
Acquisition is one side of the holding; exit is the other, and the two formats behave very differently when the holding is sold.
The 400 oz bar is highly liquid — but the liquidity is conditional. Inside the LBMA Good Delivery chain, a 400 oz bar in an approved vault under a recognized counterparty can be transacted in size with tight bid-ask, because every participant in the wholesale tier accepts the bar on the strength of its custody chain alone. The bar does not need to be inspected, re-weighed, or re-assayed. The chain itself is the warranty. This is what “the deepest pool in the market” actually means at the 400 oz tier: depth inside the network.
Outside the network, the picture inverts. A 400 oz bar that has been delivered out of an approved vault, held in a non-LBMA facility, or passed through a custody break has left the chain, and re-entry requires re-assay or re-refining at the holder’s cost. The pool of counterparties willing to transact in 400 oz bars without GDL custody is narrow, and the bid reflects that. The format is not designed to circulate outside the wholesale tier, and exit at scale outside the tier is a measurably different transaction than exit inside it.
Beyond the wholesale tier, the 1 kg bar circulates across a structurally wider counterparty universe. The same bar — refiner-accredited, serial-stamped, assay-documented — is acceptable to institutional buyers, family offices, regional dealers, refineries running a buyback desk, and qualified individuals; it transacts in markets across Asia, the Middle East, and Europe where 1 kg is the default investment-grade unit; and it does not require continuous custody at any specific facility to retain its market acceptance. Exit at the 1 kg tier is faster and operates against a far broader bid, at the cost of a wider spread than the wholesale 400 oz tier offers inside the chain. For holdings whose exit horizon is uncertain, or whose exit may not route back through the LBMA wholesale tier, that breadth is the operational point of the format.
6. Custody placement, delivery, and divisibility
Across vaulting, delivery, and divisibility, the chain-of-integrity distinction shows up in three concrete operational places: where the bar can be vaulted, what physical delivery costs in practice, and how the holding behaves when only part of it needs to move.
Vault placement. To retain Good Delivery status, a 400 oz bar has to live in an LBMA-approved vault under a recognized counterparty for the duration of the holding. The network of approved facilities is real but narrow, concentrated in London, Zurich, and a handful of other recognized centers, and movement between approved vaults is itself a controlled operation that preserves the chain. Placing a 400 oz bar in a non-approved facility is a custody decision with a price: the bar leaves the chain, and re-entry costs what section 3 described. The 1 kg bar carries no equivalent constraint. It can sit in an LBMA-approved vault, in a free-zone facility in Dubai or Singapore, or in a private allocated vault, and its market acceptance does not depend on which of those it occupied. Vault optionality is structurally wider at the 1 kg tier. In Golden Ark Reserve’s operating model, custody is contracted through Brink’s regardless of format; what differs is the set of facilities each format can route to. Allocated storage mechanics are covered on the storage page.
Physical delivery. Out-of-vault delivery is operationally heavy for both formats but disproportionately so for 400 oz. A 12.4 kg bar is operationally awkward to insure and transport: handling specifications and insurance values scale accordingly, and the delivery itself triggers the chain break that section 3 described. Delivery of 400 oz bars to a buyer’s own facility is rare in institutional practice for exactly that reason. The cost of taking the bar out of the wholesale tier is rarely justified unless the holding is being deliberately moved into a different operating mode. The 1 kg format is built to move. Bars ship in tamper-evident packaging at scales that fit standard secure-logistics protocols, multi-bar shipments split naturally into smaller consignments, and delivery does not change the bar’s market status because there is no chain to leave. Delivery mechanics and Incoterms for bullion are on the delivery page.
Divisibility. A 400 oz holding moves in 400 oz increments. One bar is one indivisible position. A holding of three bars cannot be partially sold as one and a half; it sells as one bar, two bars, or three. The format behaves as a block, and that block sizing is fine for holdings where the smallest meaningful move is twelve kilograms of gold. A 1 kg holding of equivalent total weight, twelve to thirteen bars, divides at every kilogram. A holder can sell two bars to fund a specific need, deliver three to a counterparty, and leave the rest in vault, all from the same position. Where the use case includes partial exits or reallocation across vaults, kilogram-level divisibility is the operational difference.
7. Format fit by holding profile
Across the institutional and qualified-investor universe, format choice is rarely a matter of preference. It follows from the size of the holding and what the holding is for. A few patterns hold consistently.
Central-bank-scale and very large institutional positions sit naturally in 400 oz Good Delivery bars inside the LBMA chain. The premium advantage compounds across thousands of ounces, the wholesale-tier liquidity matches the size at which these holdings transact, and the chain-of-integrity custody is itself the reporting and audit substrate the holding lives under. At this tier, block-sizing and approved-vault-only placement describe the operating model.
For corporate treasury and family-office allocations, the typical fit is 1 kg, often in deliberate combination with 400 oz. A holding at this scale is large enough to capture some of the 400 oz premium advantage on a portion of the position, but uncertain enough about exit timing and exit channel that block-sized, chain-locked metal does not fit the whole holding. The combination — a 400 oz reserve layer that minimizes acquisition cost, paired with a 1 kg layer that absorbs partial exits, partial reallocations, and any holding that may need to leave the wholesale tier — is a recognizable pattern at this scale.
At smaller scale, qualified-individual and private allocations sit almost entirely in 1 kg. The acquisition-premium difference is real but smaller in absolute terms than at institutional scale, and the operational cost of holding 400 oz — vault placement and indivisibility — is harder to absorb at private-holder size. In most markets, the 1 kg format is the default investment-grade unit at this tier, and the secondary-market breadth described in section 5 is the operational reason.
Mixed holdings are a recognized pattern in their own right. The same operational logic that drives a treasury or family office to combine the formats — a long-term reserve layer in 400 oz at the lowest acquisition cost, paired with an accessible exit layer in 1 kg — applies to any holder whose decision horizon is long but whose flexibility requirement is real. The two formats cover different operational needs of the same holding.
Both formats are available through Golden Ark Reserve at refinery-origin from Heraeus and Argor-Heraeus, with allocated storage contracted through Brink’s and international delivery on the same network. Order parameters and full format specification are on the bars hub, and counterparty verification, supply, and custody anchors sit on the company profile. At any scale where the holding has both a long-horizon reserve component and a tactical exit component, the two formats end up working together. The choice is which proportion.