# Grams to Carats (g to ct)

> Convert grams to carats: 1 g = 5 ct. Exact conversion factor, formula, 22-row table and worked examples, with JSON API and MCP access.

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

## Formula

- `1 g = 5 ct`
- `carats = grams × 5`
- Reverse: `grams = carats × 0.2`

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 g = 25 ct
- 12.5 g = 62.5 ct
- 100 g = 500 ct

## Conversion table

| Grams (g) | Carats (ct) |
| --- | --- |
| 1 | 5 |
| 2 | 10 |
| 3 | 15 |
| 4 | 20 |
| 5 | 25 |
| 6 | 30 |
| 7 | 35 |
| 8 | 40 |
| 9 | 45 |
| 10 | 50 |
| 15 | 75 |
| 20 | 100 |
| 25 | 125 |
| 30 | 150 |
| 40 | 200 |
| 50 | 250 |
| 75 | 375 |
| 100 | 500 |
| 200 | 1000 |
| 250 | 1250 |
| 500 | 2500 |
| 1000 | 5000 |

## API

- `GET https://tttkmbb.com/api/v1/convert?value=5&from_unit=g&to_unit=ct` → 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":"g","to_unit":"ct"}`
- 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 carats are in one gram?**

1 g = 5 ct. 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 grams to carats?**

Multiply the value in grams by 5: carats = grams × 5. For example, 5 g = 25 ct.

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

Multiply by the inverse factor 0.2 (grams = carats × 0.2), or use the carats-to-grams page.

## Related conversions

- [Carats to grams](https://tttkmbb.com/conversion/carats-to-grams.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)