Ounce to Grain Conversion Calculator: Free Online Tool

Convert ounces to grains with our free online weight converter.

From:

Ounce

To:

Grain

How to Use the Calculator:

Enter the value you want to convert in the 'From' field (Ounce).
The converted value in Grain will appear automatically in the 'To' field.
Use the dropdown menus to select different units within the Weight category.
Click the swap button (⇌) to reverse the conversion direction.

How to Convert Ounce to Grain

Converting Ounce to Grain involves multiplying the value by a specific conversion factor, as shown in the formula below.

Formula:

1 Ounce = 437.5 grains

Example Calculation:

Convert 5 ounces: 5 × 437.5 = 2187.5 grains

Disclaimer: For Reference Only

These conversion results are provided for informational purposes only. While we strive for accuracy, we make no guarantees regarding the precision of these results, especially for conversions involving extremely large or small numbers which may be subject to the inherent limitations of standard computer floating-point arithmetic.

Not for professional use. Results should be verified before use in any critical application. View our Terms of Service for more information.

What is a Ounce and a Grain?

The ounce (oz) is a unit of mass used in the British imperial and United States customary systems of measurement. The most common type today is the international avoirdupois ounce, defined as exactly 1/16 of an avoirdupois pound, or approximately 28.35 grams.

The grain (gr) is a unit of mass in the traditional English weight systems (Avoirdupois, Troy, and Apothecaries'). It was originally based on the weight of a single grain of barley. It is defined as exactly 64.79891 milligrams (or 1/7000 of an avoirdupois pound).

Note: The Ounce is part of the imperial/US customary system, primarily used in the US, UK, and Canada for everyday measurements. The Grain belongs to the imperial/US customary system.

History of the Ounce and Grain

The term "ounce" derives from the Roman "uncia", which was one-twelfth of the Roman pound. Its value varied throughout history and regions. The avoirdupois ounce became standardized in the English-speaking world for general trade.

The grain is one of the oldest units of mass, dating back to antiquity, using seeds (like barley or wheat) as weight standards. It formed the legal basis for English weight systems and remains defined in terms of metric units today.

Common Uses for ounces and grains

Explore the typical applications for both Ounce (imperial/US) and Grain (imperial/US) to understand their common contexts.

Common Uses for ounces

Cooking & Recipes: Standard unit in the US for measuring food ingredients like flour, sugar, spices, and non-liquid items in recipes.
Packaged Foods: Used for labeling the net weight of many packaged food products (e.g., cereal boxes, canned goods, snacks).
Postal Services: Used for determining the weight and cost of letters and small parcels, especially in the US.
Deli & Groceries: Common unit for measuring small portions of items like cheese, deli meats, and specialty foods.
Precious Metals: Often used to measure the weight of gold, silver, and other precious metals in jewelry and bullion.

Common Uses for grains

Ammunition: Measuring the mass of bullets and gunpowder charges.
Archery: Measuring the mass of arrows and arrowheads.
Medicine & Pharmacy: Historically used in the apothecaries' system; sometimes still used for measuring dosage of certain older medications (e.g., aspirin).
Jewelry: Used in the troy system (24 grains = 1 pennyweight).
Reloading: Handloading ammunition requires precise measurement in grains.

Frequently Asked Questions

Questions About Ounce (oz)

How many ounces are in a pound?

There are 16 avoirdupois ounces (oz) in 1 pound (lb).

Is an ounce the same as a fluid ounce?

No. The ounce (oz) measures mass/weight, while the fluid ounce (fl oz) measures volume.

Where is the ounce commonly used?

It is primarily used in the United States for everyday measurements, and to some extent in the UK and Canada, though metric units are more prevalent globally.

About Grain (gr)

How many grains are in an ounce (avoirdupois)?

There are 437.5 grains (gr) in 1 avoirdupois ounce (oz).

How many grains are in a pound (avoirdupois)?

There are 7,000 grains (gr) in 1 avoirdupois pound (lb).

How many milligrams are in a grain?

There are exactly 64.79891 milligrams (mg) in 1 grain (gr).

Conversion Table: Ounce to Grain

Ounce (oz)	Grain (gr)
1	437.5
5	2,187.5
10	4,375
25	10,937.5
50	21,875
100	43,750
500	218,750
1,000	437,500

All Weight Conversions

Kilogram to Gram Kilogram to Milligram Kilogram to Pound Kilogram to Ounce Kilogram to Stone Kilogram to Ton (metric)Kilogram to Ton (US)Kilogram to Ton (UK)Kilogram to Microgram Kilogram to Carat Kilogram to Slug Kilogram to Troy Ounce Kilogram to Pennyweight Kilogram to Grain Kilogram to Dram Kilogram to Quintal Kilogram to Atomic Mass Unit Kilogram to Pavan (India)Kilogram to Kati (India)Kilogram to Masha (India)Kilogram to Dina (India)Kilogram to Pras (India)Kilogram to Lota (India)Gram to Kilogram Gram to Milligram Gram to Pound Gram to Ounce Gram to Stone Gram to Ton (metric)Gram to Ton (US)Gram to Ton (UK)Gram to Microgram Gram to Carat Gram to Slug Gram to Troy Ounce Gram to Pennyweight Gram to Grain Gram to Dram Gram to Quintal Gram to Atomic Mass Unit Gram to Pavan (India)Gram to Kati (India)Gram to Masha (India)Gram to Dina (India)Gram to Pras (India)Gram to Lota (India)Milligram to Kilogram Milligram to Gram Milligram to Pound Milligram to Ounce Milligram to Stone Milligram to Ton (metric)Milligram to Ton (US)Milligram to Ton (UK)Milligram to Microgram Milligram to Carat Milligram to Slug Milligram to Troy Ounce Milligram to Pennyweight Milligram to Grain Milligram to Dram Milligram to Quintal Milligram to Atomic Mass Unit Milligram to Pavan (India)Milligram to Kati (India)Milligram to Masha (India)Milligram to Dina (India)Milligram to Pras (India)Milligram to Lota (India)Pound to Kilogram Pound to Gram Pound to Milligram Pound to Ounce Pound to Stone Pound to Ton (metric)Pound to Ton (US)Pound to Ton (UK)Pound to Microgram Pound to Carat Pound to Slug Pound to Troy Ounce Pound to Pennyweight Pound to Grain Pound to Dram Pound to Quintal Pound to Atomic Mass Unit Pound to Pavan (India)Pound to Kati (India)Pound to Masha (India)Pound to Dina (India)Pound to Pras (India)Pound to Lota (India)Ounce to Kilogram Ounce to Gram Ounce to Milligram Ounce to Pound Ounce to Stone Ounce to Ton (metric)Ounce to Ton (US)Ounce to Ton (UK)Ounce to Microgram Ounce to Carat Ounce to Slug Ounce to Troy Ounce Ounce to Pennyweight Ounce to Dram Ounce to Quintal Ounce to Atomic Mass Unit Ounce to Pavan (India)Ounce to Kati (India)Ounce to Masha (India)Ounce to Dina (India)Ounce to Pras (India)Ounce to Lota (India)Stone to Kilogram Stone to Gram Stone to Milligram Stone to Pound Stone to Ounce Stone to Ton (metric)