How to calculate gold price per gram from spot

Which gold price are you looking at?

A page labelled “gold price” can display a spot quote, an auction benchmark or a dealer’s price for a particular bar. Identify the price before comparing two screens. A spot gold quote usually gives a price in US dollars per troy ounce, with a timestamp.

The LBMA Gold Price is a London-delivery benchmark set in auctions at 10:30 and 15:00 London time, quoted in US dollars per troy ounce. A timestamp from one auction should remain attached to that observation. It does not mean a continuously updating quote.

Worked example: USD per troy ounce to USD per gram

Take an illustrative quote of USD 2,400 per troy ounce. Divide by 31.1034768 to obtain about USD 77.16 per gram. Multiplying by that factor would reverse the conversion and produce the wrong result.

Keep the full factor in the calculation and round the displayed result at the end. The ordinary ounce used for many everyday weights is a different unit. Select troy ounces when checking gold weights in the converter.

2,400 USD/ozt ÷ 31.1034768 g/ozt ≈ 77.16 USD/g
100 ozt × 31.1034768 g/ozt = 3,110.34768 g

Gross weight and fine gold content

A weight reading alone does not tell you how much gold an item contains. In an illustrative example, for an item whose stated fineness is 999 parts per thousand, 100 grams of gross weight contains 99.9 grams of fine gold by calculation. That assumes the stated weight and fineness are correct.

To estimate a metal-content value, apply a compatible fine-gold quote to the fine-gold weight. A finished bar, coin or jewellery quote can also include fabrication, a dealer premium, taxes and delivery. A mass conversion cannot calculate those charges.

Request a gold spot price

Use GET /v1/commodities/spot/XAU/USD to request gold in US dollars. Gold uses the symbol XAU and supports USD and 30 other currencies. Unsupported combinations return 404. The response below is illustrative.

The price field contains one indicative price as a decimal string. The unit is troy_ounce. The timestamp is UTC and marks the start of the minute the price belongs to. The MCP tool for a spot request is commodities_get_spot_price.

curl --request GET "https://api.narwhalapi.com/v1/commodities/spot/XAU/USD" \
  --header "Authorization: Bearer $NARWHAL_API_KEY"

# Illustrative response
{
  "symbol": "XAU-USD",
  "price": "2400.00",
  "currency": "USD",
  "unit": "troy_ounce",
  "timestamp": "2026-10-09T12:00:00Z",
  "stale": false
}

Use the calculation with commodity data

The Commodity unit converter handles gold weights. “Troy ounces to grams: conversion for metal prices” explains price-denominator calculations. Neither supplies a live gold quote.

Use the Spot API reference to check the supported instruments and response fields for your integration. The benchmark discussed here explains market conventions; its inclusion is not a claim that the named benchmark is available through Narwhal.

Show the currency, unit and timestamp next to the price. Narwhal has a daily pause from 21:00 to 22:00 UTC, when responses carry stale: true. Quotes can also be stale while markets are closed. Label a stale quote as stale and do not present it as a live market price. A conversion to grams does not change the quote’s timestamp or stale status.