# Grains to Grams (grain to g)

> Convert grains to grams: 1 grain = 0.0647989 g. Exact conversion factor, formula, 22-row table and worked examples, with JSON API and MCP access.

- Page id: `grains-to-grams` · Quantity: Mass (`mass`, base unit kg) · Tool: `convert_units`
- Canonical page: https://tttkmbb.com/conversion/grains-to-grams · This document: https://tttkmbb.com/conversion/grains-to-grams.md · JSON: https://tttkmbb.com/conversion/grains-to-grams.json (add `?value=` for a result)

## Formula

- `1 grain = 0.0647989 g`
- `grams = grains × 0.06479891`
- Reverse: `grains = grams × 15.43235835`

The factor follows from the SI definitions of both units (NIST SP 811); values below are rounded to 6 significant figures, the API returns up to 12.

## Worked examples

- 5 grain = 0.323995 g
- 12.5 grain = 0.809986 g
- 100 grain = 6.47989 g

## Conversion table

| Grains (grain) | Grams (g) |
| --- | --- |
| 1 | 0.0647989 |
| 2 | 0.129598 |
| 3 | 0.194397 |
| 4 | 0.259196 |
| 5 | 0.323995 |
| 6 | 0.388793 |
| 7 | 0.453592 |
| 8 | 0.518391 |
| 9 | 0.58319 |
| 10 | 0.647989 |
| 15 | 0.971984 |
| 20 | 1.29598 |
| 25 | 1.61997 |
| 30 | 1.94397 |
| 40 | 2.59196 |
| 50 | 3.23995 |
| 75 | 4.85992 |
| 100 | 6.47989 |
| 200 | 12.9598 |
| 250 | 16.1997 |
| 500 | 32.3995 |
| 1000 | 64.7989 |

## API

- `GET https://tttkmbb.com/api/v1/convert?value=5&from_unit=grain&to_unit=g` → unified JSON envelope with `result.values.result`, `formula`, `factor`, `sources`, `freshness`
- MCP: server `https://tttkmbb.com/mcp`, tool `convert_units` with `{"value":5,"from_unit":"grain","to_unit":"g"}`
- All mass units: https://tttkmbb.com/api/v1/units?quantity=mass · full converter: [Mass / Weight Converter](https://tttkmbb.com/conversion/mass.md)
- Authentication: none. Freshness: `static` (fixed conversion factors).

## FAQ

**How many grams are in one grain?**

1 grain = 0.0647989 g. The factor comes from the SI definitions of both units (NIST SP 811 / BIPM), so it is exact or correct to at least 10 significant figures.

**What is the formula to convert grains to grams?**

Multiply the value in grains by 0.06479891: grams = grains × 0.06479891. For example, 5 grain = 0.323995 g.

**How do I convert grams back to grains?**

Multiply by the inverse factor 15.43235835 (grains = grams × 15.43235835), or use the grams-to-grains page.

## Related conversions

- [Grams to grains](https://tttkmbb.com/conversion/grams-to-grains.md) (reverse)
- [Kilograms to Pounds](https://tttkmbb.com/conversion/kg-to-lbs.md)
- [Pounds to Kilograms](https://tttkmbb.com/conversion/lbs-to-kg.md)
- [Grams to Ounces](https://tttkmbb.com/conversion/grams-to-oz.md)
- [Ounces to Grams](https://tttkmbb.com/conversion/oz-to-grams.md)
- [Kilograms to Stone](https://tttkmbb.com/conversion/kg-to-stone.md)
- [Stone to Kilograms](https://tttkmbb.com/conversion/stone-to-kg.md)
- [Pounds to Ounces](https://tttkmbb.com/conversion/lbs-to-oz.md)
- [Ounces to Pounds](https://tttkmbb.com/conversion/oz-to-lbs.md)

## Data Sources

- NIST Special Publication 811 – Guide for the Use of the International System of Units (SI), Appendix B conversion factors — https://www.nist.gov/pml/special-publication-811 (standard, retrieved 2026-09-24)
- BIPM – The International System of Units (SI Brochure, 9th edition) — https://www.bipm.org/en/publications/si-brochure (standard, retrieved 2026-09-24)
- Wikipedia – Conversion of units — https://en.wikipedia.org/wiki/Conversion_of_units (reference, retrieved 2026-09-24)