Convert troy ounces to Mithqal

A unit defined by coinage, not by a prototype

The mithqal entered the historical record as the weight of the gold dinar struck under the Umayyad caliph Abd al-Malik at the end of the seventh century. That coin, rather than any physical standard kept in a vault, is what fixed the unit: a mithqal was simply what a full-weight dinar weighed. Surviving coins and the glass weights that Egyptian officials used to check them cluster around 4.25 grams, which is the value most numismatists and metrologists quote for the classical mithqal.

Because the anchor was a struck coin in circulation, the mithqal drifted wherever mints drifted. Persian, Ottoman and Maghrebi practice all diverged, and the range you will still see quoted — roughly 4.25 to 4.68 grams — is not measurement error but a record of separate monetary histories. A figure without a place and a period attached is therefore incomplete, and no arithmetic performed on it can repair the omission.

What the gold trade uses today

In the contemporary Gulf trade the mithqal survives as a pricing convention rather than a legal unit. Every scale in a Dubai or Riyadh gold shop is a metric balance certified under the local weights and measures authority; the mithqal appears on the price board because customers think in it. In practice the local jeweller works to a fixed conversion published by the trade association, applies it once, and settles in grams.

That habit matters for anyone reconstructing a price. When a receipt shows both a mithqal quantity and a gram total, the gram total is the transaction and the mithqal figure is the description of it. Recomputing the gram figure from the mithqal quantity using a different regional value will produce a number the shop never charged, and the discrepancy is large enough to notice: the spread between the classical and the higher regional values is close to ten per cent.

Zakat, jurisprudence and why precision is contested

The mithqal is not only a commercial unit. The nisab — the minimum wealth at which zakat becomes payable — is classically expressed as twenty mithqal of gold or two hundred dirham of silver, so the value assigned to the unit has a direct financial consequence for observant households. Different schools of jurisprudence and different national fatwa bodies publish slightly different gram equivalents, and each publishes its reasoning.

The correct practice for a conversion tool, and for anyone quoting one, is to name the authority alongside the number rather than presenting a single figure as settled. Where a reader needs a religiously operative value, the answer comes from their own reference authority; where they need a historical or commercial value, it comes from the coin evidence. Conflating the two is the most common way this unit is misused online.

The sub-units that outlived it

One mithqal divides into twenty-four qirat, and that ratio is the ancestor of the modern carat in both its senses: the metric carat of 0.2 grams used for gemstone mass, and the twenty-four-part purity scale used for gold. When a piece is described as eighteen carat, the fraction being expressed is eighteen twenty-fourths, a division inherited directly from mithqal arithmetic.

The habba, a grain weight, sits below the qirat and is still occasionally used for very small gemstone work in Egypt and the Levant. Above the mithqal, bulk gold moves in the metric kilogram bar or the troy-ounce bar of the London market, so the mithqal is confined to the retail and artisanal end of the trade. A quotation that mixes mithqal quantities with troy-ounce spot prices needs an explicit conversion chain written out, because the two systems share no common historical anchor.

Common mistakes to avoid

• Do not treat the 4.25 g classical value as a universal standard — Ottoman and Persian mithqals were measurably heavier.
• A zakat nisab figure is a jurisprudential ruling, not a metrological constant; cite the issuing authority with the number.
• The mithqal weighs metal; carat purity is a dimensionless fraction. A quote needs both, and they are not interchangeable.

Questions people ask about the Mithqal

How many grams is one mithqal?

The classical mithqal derived from the Umayyad gold dinar is about 4.25 grams. Regional standards run higher, up to roughly 4.68 grams in some Ottoman and Persian usage, so a gram figure should always be paired with the region and period it comes from.

Is the mithqal still used in the Gulf gold trade?

Yes, but as a pricing convention rather than a legal unit. Shops in the UAE, Saudi Arabia and Oman quote per mithqal while weighing and settling in grams on metric scales certified by the national weights and measures authority.

What is the relationship between the mithqal and the carat?

One mithqal was divided into twenty-four qirat. That twenty-four-part division is the direct ancestor of the modern gold purity scale, where 24-carat means pure and 18-carat means eighteen parts in twenty-four.