Millimeter of water column (mmWC) and millibar (mbar) are pressure units commonly used in industrial instrumentation, HVAC systems, ventilation, gas distribution, and low pressure measurement applications. Converting between these units is useful when pressure transmitter ranges, differential pressure instruments, calibration equipment, and engineering datasheets use different pressure scales.
One millimeter of water column is approximately equal to 0.0980665 millibar under the conventional reference conditions. To convert mmWC to mbar, multiply the pressure value in mmWC by 0.0980665.
This calculator provides a quick conversion, while the formula, worked examples, and reference table help instrumentation engineers verify pressure readings and prepare calibration values. Always confirm the specified pressure unit and reference conditions before using converted values in critical engineering calculations.
What Is Millimeter of Water Column (mmWC)?
Millimeter of water column is a pressure measurement unit based on the hydrostatic pressure exerted by a water column of one millimeter height.
It is commonly used for measuring relatively low pressure and differential pressure in industrial applications.
Instrumentation engineers frequently encounter mmWC in differential pressure transmitters, HVAC systems, ventilation ducts, boiler draft measurement, and cleanroom pressure monitoring.
What Is Millibar (mbar)?
Millibar is a metric unit of pressure commonly used in atmospheric pressure measurement, industrial process applications, and gas pressure measurement.
One millibar is equal to 100 pascals.
Millibar is frequently used in pressure gauges, pressure transmitters, gas distribution systems, and process instrumentation specifications.
Formula for mmWC to Millibar Conversion
mbar=mmWC×0.0980665
The reverse conversion is:
mmWC=mbar/0.0980665
Important conversion values:
- 1mmWC=0.0980665mbar
- 1mbar10.197162mmWC
The conversion factor assumes water density of 1000 kg/m³ at 4°C and standard gravity of 9.80665 m/s². For high precision work, use the reference conditions specified by the applicable instrument or engineering standard.
How to Convert mmWC to Millibar: Example Calculation
Suppose you have a pressure of 1000 mmWC.
To convert it to mbar:
1000×0.09807=98.07?mbar
So, 1000 mmWC is equal to 98.07 mbar.
Technical Notes
- The conversion factor assumes standard water density at 4°C (1000 kg/m³) and standard gravity (9.80665 m/s²).
- Temperature variations can cause minor deviations in actual pressure values.
- Suitable for pressures typically below 1000 mbar or 10,200 mmWC.
The following examples explain how to convert different mmWC pressure values into millibar.
Example 2: Convert 100 mmWC to mbar
Given pressure = 100 mmWC
Formula:
mbar = mmWC × 0.0980665
mbar = 100 × 0.0980665
mbar = 9.80665 mbar
Therefore, 100 mmWC is approximately 9.8067 mbar.
Example 3: Convert 500 mmWC to mbar
Given pressure = 500 mmWC
mbar = 500 × 0.0980665
mbar = 49.03325 mbar
Therefore, 500 mmWC is approximately 49.0333 mbar.
Example 4: Convert 1000 mmWC to mbar
Given pressure = 1000 mmWC
mbar = 1000 × 0.0980665
mbar = 98.0665 mbar
Therefore, 1000 mmWC is approximately 98.0665 mbar.
Example 5: Convert 2500 mmWC to mbar
Given pressure = 2500 mmWC
mbar = 2500 × 0.0980665
mbar = 245.16625 mbar
Therefore, 2500 mmWC is approximately 245.1663 mbar.
mmWC to Millibar Conversion Table
The following table provides commonly used pressure conversion values.
| Pressure in mmWC | Pressure in mbar |
| 1 | 0.09807 |
| 5 | 0.49033 |
| 10 | 0.98067 |
| 20 | 1.96133 |
| 50 | 4.90333 |
| 100 | 9.80665 |
| 200 | 19.61330 |
| 250 | 24.51663 |
| 500 | 49.03325 |
| 750 | 73.54988 |
| 1000 | 98.06650 |
| 1500 | 147.09975 |
| 2000 | 196.13300 |
| 2500 | 245.16625 |
| 5000 | 490.33250 |
| 10000 | 980.66500 |
These values use the conversion factor of 0.0980665 mbar per mmWC. The displayed values are rounded for practical engineering reference.
Common Pressure Conversion Tools
- Millimeter of Water Column (mmWC) to Millimeter of Mercury (mmHg) Pressure Unit Conversion Calculator
- Millimeter of Mercury (mmHg) to Millimeter of Water Column (mmWC) Pressure Unit Conversion Calculator
- Kilopascal (kPa) to Millimeter of Water Column (mmWC) Pressure Unit Conversion Calculator
- Millimeter of Water Column (mmWC) to Kilopascal (kPa) Pressure Unit Conversion Calculator
- Millimeter of Water Column (mmWC) to Millibar Pressure Unit Conversion Calculator
- Millibar to Millimeter of Water Column (mmWC) Pressure Unit Conversion Calculator
- Kg/cm² to Millimeter of Water Column (mmWC) Pressure Unit Conversion Calculator
- Millimeter of Water Column (mmWC) to Kg/cm² Pressure Unit Conversion Calculator
- Psi to Millimeter of Water Column (mmWC) Pressure Unit Conversion Calculator
- Millimeter of Water Column (mmWC) to Psi Pressure Unit Conversion Calculator
- Millimeter of Water Column (mmWC) to Bar Pressure Unit Conversion Calculator
- Bar to Millimeter of Water Column (mmWC) Pressure Unit Conversion Calculator
Difference Between mmWC and Millibar
Both mmWC and millibar are pressure measurement units, but they use different measurement scales.
| Parameter | mmWC | mbar |
| Full form | Millimeter of water column | Millibar |
| Measurement basis | Hydrostatic water column pressure | Metric pressure unit |
| Equivalent pressure | 9.80665 Pa | 100 Pa |
| Common applications | Low pressure and differential pressure measurement | Atmospheric and industrial pressure measurement |
| Typical use | HVAC, ventilation, and filter pressure drop | Gas systems and process pressure measurement |
mmWC is particularly convenient for expressing small pressure differences. Millibar is commonly used for general pressure measurements.
Neither unit is inherently more accurate than the other. Measurement accuracy depends on the instrument, reference conditions, and calibration method.
Uses of mmWC to Millibar Conversion Calculator:
- HVAC and Ventilation Systems: Converts mmWC readings to mbar for accurate system monitoring and pressure control.
- Water Distribution and Treatment: Useful for converting low-pressure measurements in water column systems to the more widely used millibar unit.
- Industrial Applications: Convenient for converting pressure values in low-pressure control environments and precise instrumentation systems.
This mmWC to mbar conversion calculator is an indispensable tool for professionals who need quick and accurate pressure conversions for industrial, environmental, and engineering purposes.
Refer the below link for the more Pressure Unit Conversion Calculators
Relationship Between mmWC and Other Pressure Units
The following table provides the relationship between mmWC and other commonly used pressure units.
| Pressure unit | Equivalent to 1 mmWC |
| Pascal (Pa) | 9.80665 Pa |
| Kilopascal (kPa) | 0.00980665 kPa |
| Millibar (mbar) | 0.0980665 mbar |
| Bar | 0.0000980665 bar |
| PSI | Approximately 0.00142233 psi |
These conversion factors are useful when comparing pressure transmitter ranges, pressure gauges, differential pressure instruments, and calibration equipment.
Is mmWC Equal to mbar?
No, despite their frequent use in low-pressure applications, mmWC (millimeter of water column) and mbar (millibar) are distinct pressure units.
1 mmWC = 0.0980665 mbar
Conversely, one mbar equals 10.197 mmWC.
Thus, even if both are used to gauge low pressures that is, in HVAC, fluid systems, etc. they are not equal and call for appropriate conversion.
Is 1 mmWC Equal to a Bar?
No, 1 mmWC is rather less than a bar.
1 mmWC = 9.80665 × 10?? bar
consequently: One bar represents 10,197.162 mmWC.
To equal one bar of pressure, thus, it would take over 10,000 mmWC.
Is 1 kg/cm² Equal to mmWC?
Yes, through conversion:
1 kg/cm² = 10,000 mmWC (at 4°C water density and standard gravity)
Particularly in Asian engineering systems, this is a regularly utilized conversion in water column and hydraulic applications.
What Does mmWC Pressure Mean?
Derived from the hydrostatic pressure experienced by a 1 mm high column of water at 4°C, the low-pressure unit known as millimeter of water column (mmWC)
1 mmWC = 9.80665 Pascal (Pa)
It’s often used in HVAC, gas flow measurements, and fluid level detection where extremely small pressure differences are relevant.
Frequently Asked Questions About mmWC to Millibar Conversion
How many millibar are in 1 mmWC?
1 mmWC is approximately equal to 0.0980665 mbar using conventional water column reference conditions.
How do you convert mmWC to millibar?
Multiply the pressure value in mmWC by 0.0980665. The formula is mbar = mmWC × 0.0980665.
How many millibar are in 1000 mmWC?
1000 mmWC is approximately equal to 98.0665 mbar using the conventional conversion factor.
How do you convert millibar to mmWC?
Divide the pressure value in mbar by 0.0980665. For example, 100 mbar is approximately 1019.72 mmWC.
Is mmWC the same as mmH2O?
Both terms commonly represent millimeters of water column. Check the specified reference conditions when high precision is required.
What is the difference between mmWC and mbar?
Both are pressure units, but their numerical values differ. One mmWC is approximately 0.0980665 mbar.
Where is mmWC used in instrumentation?
mmWC is commonly used for HVAC, ventilation, filter differential pressure, cleanroom pressure monitoring, boiler draft, and low pressure measurement.
Can mmWC to mbar conversion be used for transmitter calibration?
Yes. The conversion is useful when the transmitter range and reference pressure equipment use different units. Confirm the reference conditions and instrument specifications before calibration.
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