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Blood pressure unit converter

Convert an existing pressure value between mmHg and kPa without classifying the blood pressure or giving medical advice.

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Calculate your result

Enter one systolic, diastolic or other pressure value from your device or record. Do not add thousands separators; use a full stop when a comma with three following digits could be ambiguous.

Accepted range: 0 to 2000 mmHg

Your result will appear here

Nothing is saved or added to the URL.

What this result means

Choose the unit you have and enter one pressure value. The converter changes mmHg to kPa or kPa to mmHg using 1 mmHg = 0.1333224 kPa. It converts the unit only and does not interpret the reading. [1][2]

What mmHg and kPa mean

Millimetres of mercury (mmHg) and kilopascals (kPa) are two units of pressure. The SI unit of pressure is the pascal; one kilopascal is 1,000 pascals. The conventional millimetre of mercury is 133.3224 pascals. [1][2]

Why the factor is 0.1333224

NIST lists one conventional millimetre of mercury as 133.3224 pascals. Dividing by 1,000 gives 0.1333224 kPa. The reverse conversion divides kPa by 0.1333224. [1]

Convert one number at a time

A blood-pressure record often contains two separate values. Convert each number separately and keep its original role and order. Unit conversion does not calculate an average or change which number is systolic or diastolic.

Why converted displays may differ slightly

A monitor or record may already round its number. This tool calculates from the value you enter and rounds the converted display to two decimal places, so the last digit can differ from another rounded display. [1]

What this conversion cannot tell you

A converted unit has exactly the same underlying pressure information as the original. It cannot tell you whether the reading is expected for you, whether the device was used correctly, or what action to take.

Formula and assumptions

Formula
kPa = mmHg × 0.1333224. mmHg = kPa ÷ 0.1333224. [1][2]
Version
Conventional millimetre of mercury and kilopascal conversion, nist-bipm-mmhg-kpa-v1
Rounding
Calculate with the conventional 133.3224 Pa per mmHg relationship and round once for display to two decimal places.
Worked example
For 120 mmHg: 120 × 0.1333224 = 15.998688 kPa, displayed as 16.00 kPa. For 16 kPa: 16 ÷ 0.1333224 = 120.0098 mmHg, displayed as 120.01 mmHg. [1]

Who this is for — and when not to use it

Intended use

Neutral conversion of one existing pressure value between millimetres of mercury (mmHg) and kilopascals (kPa), including a systolic or diastolic number from a device or record.

Not intended for

This tool does not interpret blood pressure, decide whether a reading is high or low, combine two readings, diagnose a condition, assess symptoms, or recommend treatment.

Exclusions

  • Blood-pressure classification or diagnosis
  • Treatment or medication decisions
  • Symptom assessment or emergency triage
  • Changing, averaging or validating a device reading
  • Converting a full systolic/diastolic pair in one input

Evidence sources

  1. 1. Guide for the Use of the International System of Units (SI), Appendix B.9 — National Institute of Standards and Technology. Accessed Aug 9, 2026.
  2. 2. The International System of Units (SI Brochure), 9th edition — Bureau International des Poids et Mesures. Accessed Aug 9, 2026.