goldprice.devCalculate gold price per gram by dividing the troy ounce price by 31.1035, then multiplying by 0.999 because 24K gold is 99.9% pure. The ounce price is $3,996.20, giving a 24K gram price of $128.35. These US dollar spot values are before dealer premiums, shop charges and tax. The price time is 23 Oct 2026, 21:08 UTC.
- A troy ounce contains 31.1035 g of gold.
- Divide the ounce price by 31.1035, multiply by 0.999 for 24K gold, then multiply by your weight in grams.
- Compare with a free API gram conversion, allowing for the purity difference explained below.
Why gold prices use troy ounces
The gold spot price is quoted in US dollars per troy ounce. A troy ounce is a weight used for precious metals and is heavier than an everyday ounce. Use the troy weight when converting a gold quote into grams.
The unit changes how a price is written, but it does not change the amount of gold you own. Working in grams makes it easier to compare the reference price with a bar or another item weighed on a gram scale.
Calculate the 24K price per gram
Take the ounce price of $3,996.20, divide its dollar amount by 31.1035, then multiply by 0.999 because 24K gold is 99.9% pure. The result is $128.35 per gram. Keep the currency in US dollars throughout the calculation so the ounce and gram values can be compared directly.
This calculation gives the price for 24K gold (99.9% pure). For jewellery, the piece's purity also matters. A lower karat contains less pure gold at the same weight, so use its matching karat price before multiplying by the piece's grams.
Multiply the gram price by your weight
Multiply the gram price by the number of grams you want to value. The value is $1,283.50 for ten grams, $12,835.00 for a hundred grams and $128,350.00 for a kilogram. A kilogram contains a thousand grams.
Each longer weight uses the same gram price. The gram price comes from the ounce quote and the 24K purity adjustment, rounded to the cent. Follow that order on a calculator to calculate each value. Start with the same quote.
| Weight | Grams | Price |
|---|---|---|
| Troy ounce | 31.1035 g | $3,996.20 |
| Gram | 1 g | $128.35 |
| 10 grams | 10 g | $1,283.50 |
| 100 grams | 100 g | $12,835.00 |
| Kilogram | 1,000 g | $128,350.00 |
Check the value with the free API
The convert request below asks for the US dollar value of a gram of gold. It works without an API key or signing up. Compare the returned value with your calculation, allowing for the purity basis explained below, display rounding and quote time.
Keyless prices are 15 minutes late. The keyless limit is 100 requests an hour. A free API key allows 5,000 calls a month. For a direct ounce quote, use the gold spot endpoint.
The API's gram figures count gold as pure, while this site prices 24K gold at 99.9% purity. The API's gram figure is about 0.1% higher than the page's, so allow for this when comparing.
curl "https://api.goldprice.dev/v1/convert?from=XAU&to=USD&amount=1&unit=gram"Compare the same metal value
Check weight, purity, currency and price time before comparing another figure with these values. A gram quote for jewellery and a gram quote for 24K gold (99.9% pure) describe different amounts of gold, even when both are written in dollars.
A shop price can include a dealer premium, making charges and tax. Keep those amounts separate from the spot calculation. The calculation helps you value the metal content; the seller's full quote tells you what buying the item will cost.