How big is Grain of Rice? | Scale of the Universe

A grain of rice is a single kernel from the rice plant, Oryza sativa. The grain pictured is a long, slender grain of white rice, the kind called long-grain rice. A long grain is about 7 millimeters (0.28 inches) long and about 2 millimeters wide. Short grains are 4–5 millimeters long.

Size

Rice is sorted by the length and shape of its grains. In the United States, long-grain rice has kernels 6–8 millimeters long and three to four times as long as they are wide. Medium-grain kernels are 5–6 millimeters long and two to three times as long as they are wide. Short-grain kernels are 4–5 millimeters long, plump and almost round.

International rules draw similar lines. Under the Codex standard for rice, used in world trade, traders may call rice long grain if its kernels are 6.6 millimeters or longer, and short grain if they are under 6.2 millimeters. The International Rice Research Institute sorts brown rice into four classes, from short (under 5.5 millimeters) to extra long (over 7.5 millimeters).

A grain of milled rice weighs only a few hundredths of a gram. In a study of eight kinds of milled rice eaten in Kyrgyzstan, 1,000 grains weighed between 19.7 and 27.2 grams, so each grain weighed about 20–27 milligrams. A milligram is a thousandth of a gram.

Size comparisons

Nearly three long grains laid end to end would span a U.S. penny, which is 19 millimeters (0.75 inches) across.
A long grain is nearly twice as long as an ant 4 millimeters long.
A kilogram of milled rice holds roughly 37,000–51,000 grains, or 17,000–23,000 per pound, based on the grain weights above.
A short grain, 4–5 millimeters long, is roughly two-thirds as long as a long grain.

Inside a grain

Rice as it comes from the field, called paddy or rough rice, is wrapped in a tough outer hull. The hull makes up about a fifth of the weight of rough rice.

Removing the hull leaves brown rice, which is botanically a small dry fruit. It has thin outer layers called the bran, a tiny germ, or embryo, that can grow into a new plant, and a large starchy center called the endosperm. The endosperm makes up about 90 percent of the weight of brown rice.

Milling removes all or part of the bran and germ, leaving white rice. What remains is mostly the starchy endosperm.

Long, medium and short in the kitchen

There are more than 120,000 kinds of rice in the world, and the three grain sizes cook differently. Cooked long grains are light, fluffy and separate. Medium grains come out moist and tender and tend to cling together, which suits dishes such as risotto and paella. Short grains cook soft and sticky.

Rice is grown on every continent except Antarctica. When the United Nations named 2004 the International Year of Rice, the Food and Agriculture Organization described rice as the main food of more than half the world's people.