Convert Milligrams to Grains

Convert Milligrams to Grains Online

Easily convert milligrams (mg) to grains (gr) with this free, fast, and accurate tool. Whether you’re working in a laboratory, reloading ammunition, or calculating medication dosages, this converter gives you precise values using the official definition: 1 grain = 64.79891 milligrams.

It’s mobile-friendly, no sign-up required, and built for reliability in scientific, medical, and technical settings.

Milligrams to Grains Conversion Formula

To convert milligrams to grains, use the formula:
grains = milligrams ÷ 64.79891

Example conversions:

• 64.79891 mg = 1 grain
• 130 mg = 2.005 grains
• 500 mg = 7.717 grains

You can also reverse the formula:
milligrams = grains × 64.79891

Why Use This Milligram to Grain Converter?

• ⚖️ Ideal for pharmaceutical and scientific weight conversions
• 🔁 Supports milligrams ⇄ grains in both directions
• 📏 Accurate to five decimal places
• 📱 Fully mobile-friendly and desktop-ready
• 💊 Perfect for medication, lab samples, and reloading purposes

What Is a Grain?

A grain is a historical unit of weight that equals exactly 64.79891 milligrams. It's still used in some medical dosages and firearm reloading to measure very small weights.

While not part of the metric system, grains remain relevant in specific fields that demand high precision at small scales.

Convert Grains to Milligrams

Need the reverse? Click the “Swap” button to switch to grains to milligrams and use:
milligrams = grains × 64.79891

Example: 2 grains = 129.59782 mg