A gold melt value depends on the spot quote, weight and purity. Readers need to see those inputs to check the result. I built Gold Price Per Gram to show the inputs and the estimated fine gold content value together.
Normalize the units first
A spot price per troy ounce cannot be multiplied directly by an item weight in grams. One troy ounce is approximately 31.1034768 grams. The calculation is:
pricePerGram = spotPricePerTroyOunce / 31.1034768
fineGoldGrams = netWeightGrams * purityFraction
meltValue = pricePerGram * fineGoldGrams
With a hypothetical quote of $3,000 per troy ounce, a 4 gram item at nominal 14K purity contains about 2.333 grams of fine gold and has an estimated melt value of $225.06. These are illustrative inputs, not a live quote. Measured fineness can differ from the nominal karat fraction.
purityFraction is a decimal between 0 and 1. For nominal 14K, use 14 / 24 (approximately 0.583333), not 58.33.
Deduct non-gold weight
Deduct stones and other non-gold components before pricing the fine gold content. The calculator supports non-gold weight deductions, standard karats and custom fineness. Showing fine gold content alongside monetary value helps users check the assumptions.
Check inputs and preserve precision
For anyone implementing this formula, useful checks include finite, non-negative weights, non-gold weight no greater than total weight, and purity greater than zero and no greater than one. A calculation also needs a valid spot quote. Preserve intermediate precision and round the final displayed currency amount rather than rounding each intermediate step. These checks are recommendations for implementing the formula; the site’s internal validation and numeric representation have not been reviewed here.
Separate melt value from an offer
A payout percentage models a buyer's offer. At 80%, the example above gives approximately $180.05. Actual offers depend on assay results, fees and the buyer, so the interface displays the estimate separately from melt value. Melt value is neither jewellery retail value nor a guaranteed resale price.
Historical interface screenshot from September 29, 2026. It uses a different spot quote and an 85% payout, so its values differ from the hypothetical 80% example above.
Show the quote unit and timestamp
Display the currency, unit and quote timestamp with the monetary result. The site shows units and timestamps alongside an explanation of the calculation method.
Show individual values in a scrap lot
A scrap lot can contain items of different weights and purities. Calculate each item separately and show its value alongside the lot total, so users can check the inputs.
The project is free and requires no signup. What intermediate values would you want a calculator like this to show?
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