# Psi to Millimeters of mercury (psi to mmHg)

> Convert psi to millimeters of mercury: 1 psi = 51.7149 mmHg. Exact conversion factor, formula, 22-row table and worked examples, with JSON API and MCP access.

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

## Formula

- `1 psi = 51.7149 mmHg`
- `millimeters of mercury = psi × 51.7149252`
- Reverse: `psi = millimeters of mercury × 0.01933677746`

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 psi = 258.575 mmHg
- 12.5 psi = 646.437 mmHg
- 100 psi = 5171.49 mmHg

## Conversion table

| Psi (psi) | Millimeters of mercury (mmHg) |
| --- | --- |
| 1 | 51.7149 |
| 2 | 103.43 |
| 3 | 155.145 |
| 4 | 206.86 |
| 5 | 258.575 |
| 6 | 310.29 |
| 7 | 362.004 |
| 8 | 413.719 |
| 9 | 465.434 |
| 10 | 517.149 |
| 15 | 775.724 |
| 20 | 1034.3 |
| 25 | 1292.87 |
| 30 | 1551.45 |
| 40 | 2068.6 |
| 50 | 2585.75 |
| 75 | 3878.62 |
| 100 | 5171.49 |
| 200 | 10343 |
| 250 | 12928.7 |
| 500 | 25857.5 |
| 1000 | 51714.9 |

## API

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

1 psi = 51.7149 mmHg. 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 psi to millimeters of mercury?**

Multiply the value in psi by 51.7149252: millimeters of mercury = psi × 51.7149252. For example, 5 psi = 258.575 mmHg.

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

Multiply by the inverse factor 0.01933677746 (psi = millimeters of mercury × 0.01933677746), or use the millimeters of mercury-to-psi page.

## Related conversions

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