UnitsConverter

Millimeter of Water Column (mmH₂O) - Unit Information & Conversion

Symbol:mmH₂O
Plural:millimeters of water column
Category:Pressure

🔄 Quick Convert Millimeter of Water Column

See all Pressure conversions →

What is a Millimeter of Water Column?

Millimeter of water column (mmH₂O, mm wc) measures very low pressure by water column height in millimeters. 1 mmH₂O = 9.807 Pa ≈ 0.0361 mbar. Used in medical ventilators, CPAP machines, precision differential pressure, European HVAC.

History of the Millimeter of Water Column

Metric equivalent of inch water column. Standard in European medical equipment (ventilators, CPAP), precision instruments. More precise than inH₂O for medical respiratory pressures. Based on water manometer measurement principle.

Quick Answer

What is Millimeter of Water? Millimeter of water column (mmH₂O, mm wc) measures very low pressure by water height in millimeters. 1 mmH₂O = 9.807 Pa ≈ 0.0361 mbar. Standard for medical ventilators, CPAP therapy, precision instruments. CPAP: 40-200 mmH₂O. Use our pressure converter for conversions.

Definition

1 mmH₂O = 9.807 Pa = 0.09807 mbar = 0.001422 PSI = 0.0736 mmHg = 0.03937 inH₂O

Key relationships:

  • 25.4 mmH₂O = 1 inH₂O
  • 13.6 mmH₂O ≈ 1 mmHg
  • 102 mmH₂O ≈ 1 kPa

Physical meaning: Pressure exerted by 1-millimeter column of water at 4°C

Common Uses

Medical Ventilation: Mechanical ventilators, respiratory therapy. CPAP/BiPAP: Sleep apnea treatment pressure settings. Precision Instruments: Low differential pressure measurements. European HVAC: Clean room pressurization (metric countries).

Real-World Examples

Medical Ventilator Pressures

  • Normal breathing (peak): 10-20 mmH₂O
  • Mechanical ventilation (typical): 100-250 mmH₂O (10-25 cmH₂O)
  • Peak inspiratory pressure: 150-300 mmH₂O
  • PEEP (Positive End-Expiratory Pressure): 50-100 mmH₂O (5-10 cmH₂O)
  • High PEEP (ARDS): 100-200 mmH₂O (10-20 cmH₂O)
  • Neonatal ventilation: 80-200 mmH₂O (lower pressures)

CPAP & BiPAP Settings

  • Mild sleep apnea (CPAP): 40-60 mmH₂O (4-6 cmH₂O)
  • Moderate sleep apnea: 60-100 mmH₂O (6-10 cmH₂O)
  • Severe sleep apnea: 100-140 mmH₂O (10-14 cmH₂O)
  • BiPAP inspiratory: 100-200 mmH₂O (10-20 cmH₂O)
  • BiPAP expiratory: 40-80 mmH₂O (4-8 cmH₂O)

Respiratory Therapy Ranges

  • Incentive spirometry: 50-150 mmH₂O
  • Maximum inspiratory pressure (MIP): 600-1,000 mmH₂O
  • Maximum expiratory pressure (MEP): 800-1,200 mmH₂O
  • Airway resistance measurement: 10-100 mmH₂O
  • Lung compliance testing: 50-200 mmH₂O

Clean Room Differential Pressure

  • ISO Class 5 clean room: 5-20 mmH₂O (0.5-2 Pa)
  • ISO Class 7 clean room: 10-30 mmH₂O (1-3 Pa)
  • Hospital operating room: 15-25 mmH₂O (positive pressure)
  • Isolation room (negative): -10 to -25 mmH₂O
  • Pharmaceutical manufacturing: 10-50 mmH₂O

Precision Instruments

  • Differential pressure transmitter: 0-500 mmH₂O range
  • Magnehelic gauge: 0-250 mmH₂O typical
  • Filter pressure drop: 5-100 mmH₂O
  • Laboratory hood face velocity: 50-150 mmH₂O
  • Incubator pressure control: ±10 mmH₂O

Millimeter of Water Column Conversion Formulas

To Pascal:

1 mmH₂O = 9.80665 Pa
Example: 5 millimeters of water column = 49.03325 pascals

To Kilopascal:

1 mmH₂O = 0.009807 kPa
Example: 5 millimeters of water column = 0.049033 kilopascals

To Megapascal:

1 mmH₂O = 0.00001 MPa
Example: 5 millimeters of water column = 0.000049 megapascals

To Hectopascal:

1 mmH₂O = 0.098067 hPa
Example: 5 millimeters of water column = 0.490332 hectopascals

To Bar:

1 mmH₂O = 0.000098 bar
Example: 5 millimeters of water column = 0.00049 bars

To Millibar:

1 mmH₂O = 0.098067 mbar
Example: 5 millimeters of water column = 0.490332 millibars

To Atmosphere:

1 mmH₂O = 0.000097 atm
Example: 5 millimeters of water column = 0.000484 atmospheres

To Technical Atmosphere:

1 mmH₂O = 0.0001 at
Example: 5 millimeters of water column = 0.0005 technical atmospheres

To Torr:

1 mmH₂O = 0.073556 Torr
Example: 5 millimeters of water column = 0.36778 torr

To Millimeter of Mercury:

1 mmH₂O = 0.073556 mmHg
Example: 5 millimeters of water column = 0.36778 millimeters of mercury

To Inch of Mercury:

1 mmH₂O = 0.002896 inHg
Example: 5 millimeters of water column = 0.01448 inches of mercury

To Pound per Square Inch:

1 mmH₂O = 0.001422 psi
Example: 5 millimeters of water column = 0.007112 pounds per square inch

To Kilopound per Square Inch:

1 mmH₂O = 0.000001 ksi
Example: 5 millimeters of water column = 0.000007 kilopounds per square inch

To Kilogram-force per Square Centimeter:

1 mmH₂O = 0.0001 kgf/cm²
Example: 5 millimeters of water column = 0.0005 kilograms-force per square centimeter

To Kilogram-force per Square Meter:

1 mmH₂O = 1 kgf/m²
Example: 5 millimeters of water column = 5 kilograms-force per square meter

To Inch of Water Column:

1 mmH₂O = 0.03937 inH₂O
Example: 5 millimeters of water column = 0.19685 inches of water column

Frequently Asked Questions

Simple: Divide by 10 1 cmH₂O = 10 mmH₂O Examples (medical ventilators often use cmH₂O):

  • 100 mmH₂O = 10 cmH₂O (PEEP setting)
  • 200 mmH₂O = 20 cmH₂O (peak pressure)
  • 50 mmH₂O = 5 cmH₂O (CPAP setting)
  • 150 mmH₂O = 15 cmH₂O (typical ventilator) Medical context: "PEEP of 5" means 5 cmH₂O = 50 mmH₂O

Convert Millimeter of Water Column

Need to convert Millimeter of Water Column to other pressure units? Use our conversion tool.

Go to Pressure ConverterConvert from Millimeter of Water Column

Millimeter of Water Column Quick Info

mmH₂O
Symbol:mmH₂O
Category:Pressure
System:Various
Convert Millimeter of Water Column

Related Pressure Units

View all 16 Pressure units →

Popular Conversions

See all pressure conversions →