---
title: "Carats to Tonnes — ct to t converter"
description: "1 carat = 2 × 10^-7 tonnes. Convert carats to tonnes with a full conversion table, the exact formula, and a calculator for any value."
url: https://atoneplace.net/convert/carats-to-tonnes/
site: "At One Place"
---

# Carats to tonnes

**1 carat in tonnes: 1 ct = 2 × 10^-7 t**

t = ct × 2 × 10^-7

To convert carats to tonnes, multiply by 2 × 10^-7. The table below gives the values people look up most often, and the converter works for any number.

## Carats to tonnes table

*Common carat values converted to tonnes.*

| Carats | Tonnes |
| --- | --- |
| 1 ct | 2 × 10^-7 |
| 2 ct | 4 × 10^-7 |
| 3 ct | 6 × 10^-7 |
| 4 ct | 8 × 10^-7 |
| 5 ct | 0.000001 |
| 10 ct | 0.000002 |
| 15 ct | 0.000003 |
| 20 ct | 0.000004 |
| 25 ct | 0.000005 |
| 30 ct | 0.000006 |
| 40 ct | 0.000008 |
| 50 ct | 0.00001 |
| 75 ct | 0.000015 |
| 100 ct | 0.00002 |
| 250 ct | 0.00005 |
| 500 ct | 0.0001 |
| 1,000 ct | 0.0002 |

## How the conversion works

The relationship is t = ct × 2 × 10^-7. Both units measure mass, so the conversion is a fixed factor that never changes.

> Tonne: Also called a metric ton.

## Common questions

### How many tonnes are in one carat?

One carat equals 2 × 10^-7 tonnes. t = ct × 2 × 10^-7.

### How do you convert carats to tonnes?

Use t = ct × 2 × 10^-7. So 10 ct is 0.000002 t.

### How many carats are in one tonne?

One tonne equals 5,000,000 carats, which is the reverse of the conversion above.

### Is there more than one kind of tonne?

Also called a metric ton.

## Related pages

- [Tonnes to Carats](https://atoneplace.net/convert/tonnes-to-carats/)
- [Carats to Kilograms](https://atoneplace.net/convert/carats-to-kg/)
- [Carats to Grams](https://atoneplace.net/convert/carats-to-grams/)
- [Carats to Milligrams](https://atoneplace.net/convert/carats-to-mg/)
- [Carats to Pounds](https://atoneplace.net/convert/carats-to-lbs/)
- [Carats to Ounces](https://atoneplace.net/convert/carats-to-oz/)
- [Carats to Stone](https://atoneplace.net/convert/carats-to-stone/)

## Sources

- Guide for the Use of the International System of Units (SP 811) — NIST (https://www.nist.gov/pml/special-publication-811) [Public domain (US Government)]
- The International System of Units (SI Brochure) — Bureau International des Poids et Mesures (https://www.bipm.org/en/publications/si-brochure)
- Calculated on this page — At One Place (/about/)