# Pounds to Stone (lb to st)

> Convert pounds to stone: 1 lb = 0.0714286 st. Exact conversion factor, formula, 22-row table and worked examples, with JSON API and MCP access.

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

## Formula

- `1 lb = 0.0714286 st`
- `stone = pounds × 0.07142857143`
- Reverse: `pounds = stone × 14`

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 = 0.357143 st
- 12.5 lb = 0.892857 st
- 100 lb = 7.14286 st

## Conversion table

| Pounds (lb) | Stone (st) |
| --- | --- |
| 1 | 0.0714286 |
| 2 | 0.142857 |
| 3 | 0.214286 |
| 4 | 0.285714 |
| 5 | 0.357143 |
| 6 | 0.428571 |
| 7 | 0.5 |
| 8 | 0.571429 |
| 9 | 0.642857 |
| 10 | 0.714286 |
| 15 | 1.07143 |
| 20 | 1.42857 |
| 25 | 1.78571 |
| 30 | 2.14286 |
| 40 | 2.85714 |
| 50 | 3.57143 |
| 75 | 5.35714 |
| 100 | 7.14286 |
| 200 | 14.2857 |
| 250 | 17.8571 |
| 500 | 35.7143 |
| 1000 | 71.4286 |

## API

- `GET https://tttkmbb.com/api/v1/convert?value=5&from_unit=lb&to_unit=st` → 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":"st"}`
- 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 stone are in one pound?**

1 lb = 0.0714286 st. 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 stone?**

Multiply the value in pounds by 0.07142857143: stone = pounds × 0.07142857143. For example, 5 lb = 0.357143 st.

**How do I convert stone back to pounds?**

Multiply by the inverse factor 14 (pounds = stone × 14), or use the stone-to-pounds page.

## Related conversions

- [Stone to pounds](https://tttkmbb.com/conversion/stone-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)