The Royal Mint’s 1 oz gold Britannia contains one troy ounce of gold at 999.9 fineness. The listing gives its diameter as 32.69 mm and its face value as £100 but does not print a total weight; at that fineness the coin weighs about 31.11 g.
The numbers
| Property | Value | Source |
|---|---|---|
| Pure gold | 1 troy oz (31.1035 g) | Royal Mint listing |
| Fineness | 999.9 | Royal Mint listing |
| Diameter | 32.69 mm | Royal Mint listing |
| Face value | £100 | Royal Mint listing |
| Total weight | about 31.11 g | derived: 31.1035 ÷ 0.9999 |
A wider coin for the same gold
A Britannia, a Maple Leaf and a Philharmonic all hold one troy ounce of nearly pure gold, but they are different sizes: 32.69 mm, 30 mm and 37 mm. Same metal, different thickness. That is a good reason never to judge gold content by diameter. Compare the Maple Leaf and Philharmonic pages.
What the Royal Mint says about the design
The listing for the 2025 coin says it has four security features: a latent image that changes from a padlock to Britannia’s trident, surface animation that creates movement in the waves behind her, micro-text, and tincture lines on the Union flag on her shield. It credits Philip Nathan with the Britannia reverse and Martin Jennings with the obverse portrait, and says the coin was designed by the team behind the 12-sided £1 coin. These features matter for buyers because they are the visible checks a bullion coin offers; they say nothing about gold content, which is fixed by the 999.9 fineness. Our British sovereign guide covers the other classic British gold coin, which is a different (22-karat) standard.
Work out your own
Gold value = fine troy ounces × the price you type × number of coins. It is the metal only, not what a dealer pays or charges.
Frequently asked questions about gold in a Britannia
Is the gold Britannia pure gold?
It is 999.9 fine, effectively pure.
How big is a 1 oz gold Britannia?
32.69 mm across, according to the Royal Mint.
Does the Britannia contain more gold than a Maple Leaf?
No. Both 1 oz coins contain one troy ounce of gold.
Other coins
The same question for other popular gold coins:
- How Much Gold Is in a $20 Double Eagle?
- How Much Gold Is in a Gold Maple Leaf?
- How Much Gold Is in a Krugerrand?
- How Much Gold Is in a Vienna Philharmonic?
- How Much Gold Is in an American Gold Eagle?
For any coin, the content chart lists weight, fineness and sources, and the melt value calculator covers 27 coins at once.
Gold Coins Today publishes general information about coin collecting and precious metals, not financial, investment, tax or legal advice. Articles on this site are drafted with AI assistance (see our editorial policy) and are not written or reviewed by certified numismatists, appraisers, financial advisors or dealers. Coin and bullion values change constantly and depend on condition, authenticity and the current market — get a current appraisal or spot price from a qualified, reputable source before buying or selling, and consult a licensed financial advisor before treating precious metals as part of an investment strategy.