How many grains are in one ounce?

One avoirdupois ounce contains exactly 437.5 grains. This comes from 7,000 grains per pound divided by 16 ounces per pound.

Why is it 437.5 and not a round number?

Because the pound was defined as 7,000 grains and independently as 16 ounces. The ratio 7,000/16 = 437.5 is exact but not a whole number. The avoirdupois system's organic evolution produced these fractional relationships.

Is the troy ounce different?

Yes. The troy ounce contains exactly 480 grains (compared to 437.5 avoirdupois grains). Troy ounces are heavier and used exclusively for precious metals.

Grains to Ounces (gr to oz) Converter

1 gr = 0.0023 oz

1 Grain equals 0.0023 Ounces (1 gr = 0.0023 oz). Convert Grains to Ounces with formula, table, and examples.

One grain equals exactly 1/437.5 of an avoirdupois ounce, or approximately 0.002286 ounces. There are exactly 437.5 grains in one ounce - a number that comes from the avoirdupois system's internal arithmetic: 7,000 grains per pound divided by 16 ounces per pound equals 437.5 grains per ounce. This conversion is used when ammunition grain weights need to be expressed in ounces for packaging or shipping specifications.

How to Convert Grains to Ounces

oz = gr × 0.0022857143

Multiply the value in Grains by 0.0022857143

Take your value in Grains
Multiply by 0.0022857143
Read the result in Ounces

Common Grains to Ounces Conversions

Grains (gr)	Ounces (oz)	Status
1 gr	0.00228571 oz
5 gr	0.01142857 oz
10 gr	0.02285714 oz
20 gr	0.04571429 oz
50 gr	0.11428571 oz
100 gr	0.22857143 oz
200 gr	0.45714286 oz
437.5 gr	1 oz
480 gr	1.09714286 oz
500 gr	1.14285714 oz
875 gr	2 oz
1,000 gr	2.28571429 oz
5,000 gr	11.42857143 oz
7,000 gr	16 oz

Good to Know About Grains to Ounces Conversion

The grain is remarkable for being the only unit identical across all three traditional English weight systems (troy, avoirdupois, and apothecary). This universality made it the natural foundation for the entire English measurement tradition. While ounces and pounds changed definition depending on whether you were weighing gold, groceries, or medicine, the grain remained constant: always 64.80 milligrams, everywhere, for everyone.

Grains to Ounces: What You Need to Know

A 230-grain .45 ACP bullet weighs about 0.526 ounces - just over half an ounce. A box of 50 such bullets weighs about 26.3 ounces. Ammunition retailers who sell by the box need this conversion when calculating shipping weights in ounces or pounds. The 437.5 grains-per-ounce factor is one of the most frequently used within the avoirdupois system by the shooting community.

What is a Grain? gr

A grain is a unit of mass equal to exactly 64.79891 milligrams. It is the same in the avoirdupois, troy, and apothecaries' systems, derived from the 1959 international agreement defining the pound as exactly 0.45359237 kilograms.

Imperial Troy Apothecaries ammunition weight bullet measurement historical pharmacy

Learn more about Grain →

What is a Ounce? oz

An imperial and US customary unit of mass equal to approximately 28.35 grams. Commonly used in the US and UK for food and postal weight.

Imperial Us-customary food packaging (US/UK) postal weight cooking (US)

Learn more about Ounce →

Going the other way? Use our Ounces to Grains converter.

Grains to Ounces FAQ

One avoirdupois ounce contains exactly 437.5 grains. This comes from 7,000 grains per pound divided by 16 ounces per pound.
Because the pound was defined as 7,000 grains and independently as 16 ounces. The ratio 7,000/16 = 437.5 is exact but not a whole number. The avoirdupois system's organic evolution produced these fractional relationships.
Yes. The troy ounce contains exactly 480 grains (compared to 437.5 avoirdupois grains). Troy ounces are heavier and used exclusively for precious metals.

Non-Frequently Asked Questions About Grains to Ounces

Questions nobody should ask - but someone did.

Shotshells contain many small pellets whose total weight is conveniently expressed in ounces (e.g., 1 1/8 oz of shot). Rifle bullets are single projectiles whose weight is more naturally expressed in grains (e.g., 168 grains). The shooting sports community uses both units daily, switching between them depending on whether they are loading a shotgun or a rifle.
Serious handloaders and ballisticians know it, though they rarely need the full number. Most grain-to-ounce conversions are done by calculator or by knowing that 1 ounce is 'about 438 grains.' The fractional 0.5 matters for precise work but is often dropped for quick estimation.
A typical sandwich weighs about 6 to 8 ounces (2,625 to 3,500 grains). Describing your lunch as '3,000 grains of turkey on rye' would be technically accurate and socially unusual. The grain was designed for pinches, not for sandwiches.