# Pounds to Metric tons (tonnes) (lb to t)

> Convert pounds to metric tons (tonnes): 1 lb = 0.000453592 t. Exact conversion factor, formula, 22-row table and worked examples, with JSON API and MCP access.

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

## Formula

- `1 lb = 0.000453592 t`
- `metric tons (tonnes) = pounds × 0.00045359237`
- Reverse: `pounds = metric tons (tonnes) × 2204.622622`

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 lb = 0.00226796 t
- 12.5 lb = 0.0056699 t
- 100 lb = 0.0453592 t

## Conversion table

| Pounds (lb) | Metric tons (tonnes) (t) |
| --- | --- |
| 1 | 0.000453592 |
| 2 | 0.000907185 |
| 3 | 0.00136078 |
| 4 | 0.00181437 |
| 5 | 0.00226796 |
| 6 | 0.00272155 |
| 7 | 0.00317515 |
| 8 | 0.00362874 |
| 9 | 0.00408233 |
| 10 | 0.00453592 |
| 15 | 0.00680389 |
| 20 | 0.00907185 |
| 25 | 0.0113398 |
| 30 | 0.0136078 |
| 40 | 0.0181437 |
| 50 | 0.0226796 |
| 75 | 0.0340194 |
| 100 | 0.0453592 |
| 200 | 0.0907185 |
| 250 | 0.113398 |
| 500 | 0.226796 |
| 1000 | 0.453592 |

## API

- `GET https://tttkmbb.com/api/v1/convert?value=5&from_unit=lb&to_unit=t` → 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":"lb","to_unit":"t"}`
- 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 metric tons (tonnes) are in one pound?**

1 lb = 0.000453592 t. 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 pounds to metric tons (tonnes)?**

Multiply the value in pounds by 0.00045359237: metric tons (tonnes) = pounds × 0.00045359237. For example, 5 lb = 0.00226796 t.

**How do I convert metric tons (tonnes) back to pounds?**

Multiply by the inverse factor 2204.622622 (pounds = metric tons (tonnes) × 2204.622622), or use the metric tons (tonnes)-to-pounds page.

## Related conversions

- [Metric tons (tonnes) to pounds](https://tttkmbb.com/conversion/tonnes-to-lbs.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)