Momme
Also: Monme, mom, もんめ
Japanese unit of weight from the traditional shakkanho system, used today mainly in the pearl trade, equal to exactly 3.75 grams.
The momme (Japanese: 匁, pronounced monme) is a traditional Japanese unit of weight from the shakkanho system, equal to exactly 3.75 grams. In modern trade the momme has retained a clearly defined niche: it is the internationally most common unit of weight for cultured and natural pearls, particularly in the Japanese and Asian pearl markets.
Origin and historical context
The shakkanho system was the official Japanese system of measures and weights until the metric switchover in 1891. Within it, the momme was the base unit for precious-metal and jewellery weights. 160 momme traditionally made up one kin (600 g). In the 19th century the momme was exported into the Western world through the pearl trade, where it has survived to this day as an industry standard.
Conversion table
| Unit | Value |
|---|---|
| 1 momme | 3.75 g |
| 1 momme | 57.870 troy grains |
| 1 momme | 2.411 pennyweight (dwt) |
| 1 momme | 0.1206 troy ounces |
| 1 momme | 0.1323 avoirdupois ounces |
| 10 momme | 37.5 g |
Significance in the precious-metal and pearl trade
In the precious-metal trade the momme today plays only a minor role - here the troy ounce, gram and pennyweight dominate. It is different in the pearl market: loose pearls are often given a momme price there. A pearl necklace with a total weight of 10 momme therefore weighs 37.5 grams.
Anyone valuing historical Japanese silver or gold coins (e.g. ichibu-kin, isshu-gin) will likewise come across momme figures. To calculate the melt value of such pieces correctly, conversion into grams is the first step.
Formula box
Weight in grams = momme × 3.75
Weight in momme = grams ÷ 3.75
The current gold price per gram can be converted directly onto a momme basis using this conversion factor, for example when valuing scrap or broken gold from Asia. Use the Unit Converter for quick conversions between momme, grams, pennyweight and other units.
Distinction from similar units
The momme is not to be confused with the Chinese tael (37.4-50.0 g depending on the region) or the Indian tola (approx. 11.664 g). The Taiwanese tael happens to equal exactly 37.5 g, and thus 10 momme - the widespread Hong Kong variant (37.429 g), however, differs. All three units originate from regional precious-metal traditions in Asia and have survived in specific market segments, while the metric system dominates everyday use.
In brief
The momme equals exactly 3.75 grams and is relevant today mainly in the pearl trade and in the valuation of historical Japanese precious-metal pieces. For a melt-value calculation, a simple multiplication by 3.75 is sufficient.