A minted 1 oz gold bar measures about 41 × 24 × 1.8 mm — roughly the size of a postage stamp, and thinner than two credit cards. Dimensions vary a little by mint and more by type: minted bars are thin and precise, cast bars are chunkier and irregular. Here are the real numbers for the major brands, what the assay card adds, and how a 1 oz bar compares to the sizes around it.
1 oz Gold Bar Dimensions by Brand
| Bar | Dimensions (L × W × Thickness) | Weight |
|---|---|---|
| PAMP Suisse Lady Fortuna 1 oz (minted) | 41 × 24 × 1.83 mm | 31.1 g |
| Credit Suisse 1 oz (minted) | 41 × 24 × 1.8 mm | 31.1 g |
| Perth Mint 1 oz (minted) | 41 × 24 × 1.7 mm | 31.1 g |
| Valcambi 1 oz (minted) | 41 × 24 × 1.8 mm | 31.1 g |
| Cast / poured 1 oz bars | Roughly 40 × 22 mm, thickness varies ~2.5–4 mm | 31.1 g |
| Assay card (sealed package) | About 85 × 54 mm — credit-card size | — |
Gold’s density (19.3 g/cm³) is why an ounce fits in such a small footprint — the same ounce of silver needs about 1.8× the volume. If a “1 oz” bar is dramatically larger than 41 × 24 mm at minted thickness, weigh it: correct weight plus correct dimensions is the first authenticity screen, and our how to verify a gold bar guide covers the full test sequence.
How the Sizes Stack Up
The 1 oz does not live alone. The 1 gram gold bar is a 15 × 8.5 mm sliver; the 100 gram gold bar runs about 47 × 27 × 7.8 mm minted — the first size that feels like a bar in the hand. Buyers comparing formats should read fractional gold premiums alongside: smaller bars cost more per gram, and the 1 oz is the sweet spot where premiums drop toward wholesale. Our ranking of the best 1 oz gold bars to buy covers brands and live dealer premiums.
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FAQ
How big is a 1 oz gold bar?
About 41 × 24 × 1.8 mm for minted bars from PAMP, Credit Suisse, Perth, and Valcambi — smaller than a postage stamp is wide, and about as thick as two stacked credit cards. In its sealed assay card, the package is credit-card sized (85 × 54 mm).
How much does a 1 oz gold bar weigh in grams?
31.1035 grams — one troy ounce. (The conversion family is covered in our grams in a troy ounce chart.)
Why are cast 1 oz bars thicker than minted ones?
Cast bars are poured into open molds, so they trade dimensional precision for a rustic finish; the same 31.1 g of gold ends up in a smaller footprint with more thickness. Weight and purity are identical — only the shape changes.
Can dimensions verify a gold bar?
They are the first screen, not the verdict: correct dimensions + correct weight (31.10 g) + a specific-gravity or XRF test is the reliable sequence. Tungsten-filled fakes match weight or size, rarely both plus gravity.
Educational content only — not financial advice. Dimensions are manufacturer specifications; small tolerances apply, and cast bars vary by pour.