# Bar to Megapascals (bar to MPa)

> Convert bar to megapascals: 1 bar = 0.1 MPa. Exact conversion factor, formula, 22-row table and worked examples, with JSON API and MCP access.

- Page id: `bar-to-mpa` · Quantity: Pressure (`pressure`, base unit Pa) · Tool: `convert_units`
- Canonical page: https://tttkmbb.com/conversion/bar-to-mpa · This document: https://tttkmbb.com/conversion/bar-to-mpa.md · JSON: https://tttkmbb.com/conversion/bar-to-mpa.json (add `?value=` for a result)

## Formula

- `1 bar = 0.1 MPa`
- `megapascals = bar × 0.1`
- Reverse: `bar = megapascals × 10`

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 bar = 0.5 MPa
- 12.5 bar = 1.25 MPa
- 100 bar = 10 MPa

## Conversion table

| Bar (bar) | Megapascals (MPa) |
| --- | --- |
| 1 | 0.1 |
| 2 | 0.2 |
| 3 | 0.3 |
| 4 | 0.4 |
| 5 | 0.5 |
| 6 | 0.6 |
| 7 | 0.7 |
| 8 | 0.8 |
| 9 | 0.9 |
| 10 | 1 |
| 15 | 1.5 |
| 20 | 2 |
| 25 | 2.5 |
| 30 | 3 |
| 40 | 4 |
| 50 | 5 |
| 75 | 7.5 |
| 100 | 10 |
| 200 | 20 |
| 250 | 25 |
| 500 | 50 |
| 1000 | 100 |

## API

- `GET https://tttkmbb.com/api/v1/convert?value=5&from_unit=bar&to_unit=MPa` → 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":"bar","to_unit":"MPa"}`
- All pressure units: https://tttkmbb.com/api/v1/units?quantity=pressure · full converter: [Pressure Converter](https://tttkmbb.com/conversion/pressure.md)
- Authentication: none. Freshness: `static` (fixed conversion factors).

## FAQ

**How many megapascals are in one bar?**

1 bar = 0.1 MPa. 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 bar to megapascals?**

Multiply the value in bar by 0.1: megapascals = bar × 0.1. For example, 5 bar = 0.5 MPa.

**How do I convert megapascals back to bar?**

Multiply by the inverse factor 10 (bar = megapascals × 10), or use the megapascals-to-bar page.

## Related conversions

- [Megapascals to bar](https://tttkmbb.com/conversion/mpa-to-bar.md) (reverse)
- [Psi to Bar](https://tttkmbb.com/conversion/psi-to-bar.md)
- [Bar to Psi](https://tttkmbb.com/conversion/bar-to-psi.md)
- [Psi to Kilopascals](https://tttkmbb.com/conversion/psi-to-kpa.md)
- [Kilopascals to Psi](https://tttkmbb.com/conversion/kpa-to-psi.md)
- [Bar to Kilopascals](https://tttkmbb.com/conversion/bar-to-kpa.md)
- [Kilopascals to Bar](https://tttkmbb.com/conversion/kpa-to-bar.md)
- [Atmospheres to Pascals](https://tttkmbb.com/conversion/atm-to-pa.md)
- [Pascals to Atmospheres](https://tttkmbb.com/conversion/pa-to-atm.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)