Free Ratti to Carat Converter

Type a weight above in ratti, carats, grams or milligrams, and this free converter gives the same weight in every unit. A weight in ratti is shown in both of the conventions in use: the gem trade ratti, also called pakki ratti, of 182.25 mg, which is about 0.91 carat, and the older goldsmith ratti, the sunari ratti, of 121.5 mg, which is about 0.61 carat. For example, 5.25 ratti is 4.78 carats as gem trade ratti, or 3.19 carats as goldsmith ratti. A second part gives one modern book’s rule of thumb for a stone’s weight from body weight, with its limits stated plainly.

How it works

The carat used for gems today is the metric carat of 200 mg, adopted at the Fourth General Conference on Weights and Measures in Paris in 1907. One carat is therefore 0.2 gram.

The goldsmith ratti comes from the Indian goldsmith’s table, in which 8 ratti make 1 masha and 12 masha make 1 tola, so a tola is 96 ratti. In British India the tola was fixed at 180 troy grains, which is 11.6638 grams, by Regulation VII of 1833, as the article on the tola in the English Wikipedia records. A ninety-sixth of that is 121.5 mg to the nearest tenth of a milligram, and 121.5 mg, or 0.1215 g, is also the standardised weight of the ratti given by F. R. Allchin in “An Inscribed Weight from Mathura” (Journal of the Economic and Social History of the Orient, volume 7, number 2, 1964). The tool uses 121.5 mg.

The gem trade ratti is one and a half goldsmith ratti, 182.25 mg. This is the conversion for astrological gemstones in the table of jewellers’ units in the English Wikipedia article on the ratti, which gives the pakki ratti as 1.5 times the sunari ratti of 121.5 mg. The gemstone module of our Pro app uses the same two figures, 0.91 and 0.61 carat.

Reading the result

The headline gives the weight you typed in carats under each ratti, and the grams. A table then gives the same weight in carats, grams, milligrams, gem trade ratti and goldsmith ratti. Carats, ratti and milligrams are rounded half up to two decimals and grams to three, so 1 gem trade ratti shows as 0.91 carat and 1 goldsmith ratti as 0.61 carat. Going the other way, 1 carat is 1.1 gem trade ratti or 1.65 goldsmith ratti, and 1 gram is 5.49 gem trade ratti or 8.23 goldsmith ratti.

A small table at the end gives 1 to 12 ratti in carats under both conventions, for reading a seller’s list at a glance. Whichever ratti a seller uses, the safest habit is the one our buying guide gives: have the weight written on the invoice in carats or grams.

The body weight part divides the weight in kg by 10 and gives the result in ratti, rounded half up to two decimals, with the same figure in carats under each ratti. For example, 65 kg gives about 6.5 ratti, which is 5.92 carats as gem trade ratti or 3.95 carats as goldsmith ratti. The note under it names the book and says what the figure is not.

Where traditions differ

The ratti began as the weight of a seed, the gunja seed, and seeds vary, which is one reason more than one ratti is in use. Even the old tables differ: the goldsmith’s table counts 96 ratti to the tola, while R. M. Martin, in his Statistics of the Colonies of the British Empire (1839), wrote that a tola was the weight of 100 ratti seeds, as the Wikipedia article on the tola notes. The two conventions in this tool are the two that the jewellers’ table names, and the gap between them is large: a gem trade ratti is one and a half goldsmith ratti. Always ask which one a seller means.

Some modern books also suggest a stone’s weight from the wearer’s body weight. The second part of this tool gives one such rule of thumb, from one named book: Pt. Kapil Mohan’s Ratna Uparatna aur Nag Nagina Sampurna Gyan (Randhir Prakashan, Haridwar), which gives about 1 ratti for each 10 kg of body weight as the view of most scholars. No classical text gives such a rule. Other modern books divide the body weight by other figures, so they arrive at other weights, and since a ratti can mean either of two weights, the tool shows the figure in carats under both. It is not advice to buy a stone of that size. Astrologers differ on how heavy a stone should be, and a larger stone is not stronger by that fact, as our buying guide says. The weight is a question for the reader who saw your chart.

What it does not do

It does not tell you which stone to wear, how heavy it should be or what it should cost, and it does not judge a stone’s quality or whether it is natural. A laboratory report does that. For which stones are usually considered for your chart, see the gemstone suggestion calculator. A gemstone is an educational topic here, as tradition describes it, and not a promise of any result.

Frequently asked questions