Sterling silver marked .925 contains 92.5% silver. To estimate its melt value per gram, divide your entered silver spot price per troy ounce by 31.1035, then multiply by 0.925. For a solid sterling item, multiply that result by its metal weight in grams.
For example, an entered spot price of $30 per troy ounce gives about $0.89 of silver content per gram of sterling. A 100-gram sterling lot would have about $89.22 of theoretical melt value. At an entered 80% payout, the offer estimate would be about $71.37 before fees. These are worked examples, not current silver quotes.
The calculator displays melt value per gram, pennyweight, and troy ounce for the selected purity. Subtract stones and non-silver parts first. Weighted handles and silver-plated items cannot be valued as solid sterling simply from their total weight.