Calculate a user-entered gold-value scenario
Enter a total weight, purity, price per troy ounce, and scenario percentage. The price and percentage are explicit user-entered arithmetic assumptions. Weight can be grams, avoirdupois ounces, troy ounces, or pennyweight. Purity can be entered by karat or percent.
Unit and purity method
The scenario first converts gross weight to grams: 28.349523125 g per avoirdupois ounce, 31.1034768 g per troy ounce, and 1.55517384 g per pennyweight. NIST Handbook 44 Appendix C lists these gram factors in its general mass table. As a publisher-derived cross-check, the exact 453.59237 g avoirdupois pound, 16 avoirdupois ounces per pound, 7,000 grains per pound, 480 grains per troy ounce, and 24 grains per pennyweight reproduce all three factors without rounding.
For this calculator, entered karat is transparently normalized against the accepted 24-karat endpoint as entered karat / 24; this is publisher-derived arithmetic, not a quoted regulatory definition. Percent purity is divided by 100. Pure grams are converted to troy ounces, multiplied by the entered price assumption, then multiplied by the entered scenario percentage.
For 10 g of 18-karat gold, 18/24 gives 75% purity and 7.5 g of pure gold, or about 0.2411 troy oz. With an entered price assumption of $2,000 per troy ounce, the value before the scenario percentage is $482.26; an entered scenario percentage of 90% gives $434.04. At 100%, the result would equal $482.26, so the $48.22 difference is solely the effect of the entered percentage.
Scenario checks
Check the entered weight and unit, karat or purity percentage, price assumption, and scenario percentage assumption. The selected karat or purity does not verify the item’s composition, and the result does not establish actual recoverable gold.
Weight and entered price cannot be negative; purity and scenario percentage are limited to 0%–100%. Unknown units or purity modes, blanks, and invalid numeric values are invalid. Zero weight, purity, price, or scenario percentage produces zero value. A selected or entered purity is a scenario input and does not establish actual recoverable content.
This is neither an appraisal nor investment, tax, or legal advice.
Sources
- NIST, Handbook 44 (2026), Appendix C — “Units of Mass Not Greater Than Pounds and Kilograms” gram-column factors and the general avoirdupois/troy unit relationships used in the publisher-derived cross-check.
- eCFR, 16 CFR § 23.3 — identifies fine gold as 24 karat, gold alloy as less than 24 karats, and examples of correct karat-fineness designations. Footnote 31 states the 12-karat/24-karat half-fine-gold equivalence.