Grains to Grams Converter – Precise gr to g Conversion in 3 Easy Steps

Use this free grains to grams converter to switch between grains (gr) and grams (g) with high precision. Type in either box and the other updates instantly, the formula panel shows the exact working, and a table lists common projectile weights already converted. It is useful for reloading records, archery, jewellery, pharmacy history and any task where small weights matter.

The grain is one of the oldest units of weight still in use. It is tiny, about 65 milligrams, which makes it handy for very light items but awkward to compare with metric figures on scales, data sheets and packaging.

This grains to grams converter does the maths both ways with the exact definition. It runs in your browser.

What Is a Grain?

The grain was originally based on the weight of a single grain of barley or wheat. Today it is defined exactly as 64.79891 milligrams. It is the same in the avoirdupois, troy and apothecaries’ systems, which makes it a common link between them.

• 7,000 grains = 1 avoirdupois pound
• 437.5 grains = 1 avoirdupois ounce
• 480 grains = 1 troy ounce (used for precious metals)
• 1 grain ≈ 64.8 milligrams

Grains to Grams Formulas

• Grams = grains × 0.06479891
• Grains = grams ÷ 0.06479891 (or grams × 15.4324)
• Milligrams = grains × 64.79891

Grains to Grams Conversion Table

How to Use the Grains to Grams Converter

Step 1: Enter a Weight in Grains

Type a value in the Grains box. 350 gr converts to 22.67962 g, and the formula panel shows 350 × 0.06479891 so you can check the result.

Step 2: Convert Grams to Grains

Type in the Grams box to go the other way. 25 g converts to 385.81 gr, and the formula switches to division.

Step 3: Use the Common Weights Table

The table under the converter lists popular projectile weights from 55 gr to 405 gr with their gram equivalents, ready for quick reference. Use the copy buttons to paste either value into a log or spreadsheet.

Where Grains Are Still Used

• Archery: arrow shafts, inserts and points are weighed in grains. Field points of 100 or 125 grains are common, and total arrow weight affects speed and penetration.
• Ammunition: bullet and powder weights are traditionally given in grains on boxes and data sheets.
• Pharmacy history: older prescriptions and some aspirin labels used grains; a 5-grain aspirin tablet is about 325 mg.
• Precious metals and gems: the grain is part of the troy system, and pearl grains are a separate jewellery unit.
• Textiles and fibres: some yarn and fibre measurements use grains per yard.

Safety and Accuracy Tips

• For anything safety-critical, weigh with a calibrated scale and follow the manufacturer’s published data; never rely on a conversion alone.
• Keep enough decimal places when converting small charges or doses, then round only at the end.
• Do not confuse the jeweller’s pearl grain (50 mg) or the metric carat (200 mg) with the standard grain.

Need other unit conversions? Try the Gas Mark to Celsius Converter in the kitchen or the Density Converter for materials.

Frequently Asked Questions