# Millimeters of mercury to Psi (mmHg to psi)

> Convert millimeters of mercury to psi: 1 mmHg = 0.0193368 psi. Exact conversion factor, formula, 22-row table and worked examples, with JSON API and MCP access.

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

## Formula

- `1 mmHg = 0.0193368 psi`
- `psi = millimeters of mercury × 0.01933677746`
- Reverse: `millimeters of mercury = psi × 51.7149252`

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 mmHg = 0.0966839 psi
- 12.5 mmHg = 0.24171 psi
- 100 mmHg = 1.93368 psi

## Conversion table

| Millimeters of mercury (mmHg) | Psi (psi) |
| --- | --- |
| 1 | 0.0193368 |
| 2 | 0.0386736 |
| 3 | 0.0580103 |
| 4 | 0.0773471 |
| 5 | 0.0966839 |
| 6 | 0.116021 |
| 7 | 0.135357 |
| 8 | 0.154694 |
| 9 | 0.174031 |
| 10 | 0.193368 |
| 15 | 0.290052 |
| 20 | 0.386736 |
| 25 | 0.483419 |
| 30 | 0.580103 |
| 40 | 0.773471 |
| 50 | 0.966839 |
| 75 | 1.45026 |
| 100 | 1.93368 |
| 200 | 3.86736 |
| 250 | 4.83419 |
| 500 | 9.66839 |
| 1000 | 19.3368 |

## API

- `GET https://tttkmbb.com/api/v1/convert?value=5&from_unit=mmHg&to_unit=psi` → 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":"mmHg","to_unit":"psi"}`
- 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 psi are in one millimeter of mercury?**

1 mmHg = 0.0193368 psi. 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 millimeters of mercury to psi?**

Multiply the value in millimeters of mercury by 0.01933677746: psi = millimeters of mercury × 0.01933677746. For example, 5 mmHg = 0.0966839 psi.

**How do I convert psi back to millimeters of mercury?**

Multiply by the inverse factor 51.7149252 (millimeters of mercury = psi × 51.7149252), or use the psi-to-millimeters of mercury page.

## Related conversions

- [Psi to millimeters of mercury](https://tttkmbb.com/conversion/psi-to-mmhg.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)