Convert gold karats to purity percentage or fineness, reverse percentage to karats, and calculate pure-gold and alloy weight in common jewelry units. Determine the pure gold content in jewelry or scrap gold based on its karat rating. Enter the total weight, select the karat (9K through 24K), and get the exact pure gold and alloy amounts. The above “Breakdown” information could be used to estimate/calculate 14K or 18K gold in other lighter or heavier N size watches (for example: watches having open face or box hinge cases). It’s important to find out how much gold is used to produce a watch as vintage watches with basic movements or vintage watches which are not working at all are priced by the weight and the gold’s value. Estimate how heavy a watch is in stainless steel, titanium, gold, ceramic or bronze. Compare materials at the same case size and see the weight difference before you buy. Pick whether you want to estimate weight from size, or find pure-gold content from a known total weight. This converter turns any karat into its fineness and percentage, and works out the pure-gold weight inside a piece once you enter its gross weight. No spot price needed — this is about purity and weight, not dollars. For instance, a 24K gold watch contains 99.9% pure gold, while an 18K gold watch contains 75% pure gold. The higher the karatage, the more valuable the watch. 2. Weight: The weight of the gold used in a watch is another crucial factor influencing its value. Select your karat, and this gold purity calculator instantly converts it to a fineness percentage and pure gold content - from 999 fine through 916, 750, 585, and beyond, with the exact grams of pure gold in any weight you enter. Convert karats, fineness, and percentages, then estimate pure gold and alloy weight before testing or selling gold.