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Inch of Water Column to Kilopascal Converter

Convert inches of water column to kilopascals with our free online pressure converter.

Quick Answer

1 Inch of Water Column = 0.249089 kilopascals

Formula: Inch of Water Column × conversion factor = Kilopascal

Use the calculator below for instant, accurate conversions.

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All conversion formulas on UnitsConverter.io have been verified against NIST (National Institute of Standards and Technology) guidelines and international SI standards. Our calculations are accurate to 10 decimal places for standard conversions and use arbitrary precision arithmetic for astronomical units.

Last verified: February 2026Reviewed by: Sam Mathew, Software Engineer

Inch of Water Column to Kilopascal Calculator

How to Use the Inch of Water Column to Kilopascal Calculator:

  1. Enter the value you want to convert in the 'From' field (Inch of Water Column).
  2. The converted value in Kilopascal will appear automatically in the 'To' field.
  3. Use the dropdown menus to select different units within the Pressure category.
  4. Click the swap button (⇌) to reverse the conversion direction.
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How to Convert Inch of Water Column to Kilopascal: Step-by-Step Guide

Converting Inch of Water Column to Kilopascal involves multiplying the value by a specific conversion factor, as shown in the formula below.

Formula:

kPa = inH₂O × 0.249089

Example Calculation:

1 inH₂O = 0.249089 kPa

Disclaimer: For Reference Only

These conversion results are provided for informational purposes only. While we strive for accuracy, we make no guarantees regarding the precision of these results, especially for conversions involving extremely large or small numbers which may be subject to the inherent limitations of standard computer floating-point arithmetic.

Not for professional use. Results should be verified before use in any critical application. View our Terms of Service for more information.

Need to convert to other pressure units?

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📋 Unit Symbols

Copy inH₂O & kPa symbols

What is a Inch of Water Column and a Kilopascal?

1 inH₂O = 249.1 Pa = 2.491 mbar = 0.2491 hPa = 0.0361 PSI = 0.00249 bar = 0.0736 inHg = 1.868 mmH₂O

Also written as: in wc (inches water column), "H₂O, inAq

Physical meaning: Pressure exerted by 1-inch column of water at standard conditions

1 kPa = 1,000 Pa = 0.145038 PSI = 0.01 bar = 10 hPa = 10 mbar = 0.00987 atm = 7.5 mmHg

Why Kilopascal?

The kilopascal is the practical SI unit for everyday pressures:

  • Pascal is too small: 1 Pa = fingernail scratch pressure (not useful)
  • Megapascal is too large: 1 MPa = industrial level (uncommon for most uses)
  • Kilopascal is "just right": 100-300 kPa range covers most everyday pressures
  • SI standard: International standard for tire pressure, medical, engineering
  • Clean conversions: Exactly 0.145 PSI, exactly 0.01 bar

Note: The Inch of Water Column is part of the imperial/US customary system, primarily used in the US, UK, and Canada for everyday measurements. The Kilopascal belongs to the imperial/US customary system.

Common Uses and Applications: inches of water column vs kilopascals

Explore the typical applications for both Inch of Water Column (imperial/US) and Kilopascal (imperial/US) to understand their common contexts.

Common Uses for inches of water column

HVAC: Duct pressure, fan static pressure, filter pressure drop. Building Systems: Room pressurization, clean room differentials. Industrial: Low-pressure gas systems, ventilation. Testing: Air tightness testing, pressure differential measurements.

When to Use kilopascals

Automotive: Tire pressure (international standard, except USA).

  • Car manufacturers specify tire pressure in kPa on door jamb
  • Repair manuals use kPa
  • Tire pressure gauges often have kPa scale

Medical: Blood pressure equipment (replacing mmHg in some regions).

  • Modern digital blood pressure monitors often display kPa
  • Medical research uses kPa
  • Gradual transition from mmHg (some regions still use mmHg)

Meteorology: Atmospheric pressure (101.325 kPa at sea level).

  • European weather reports sometimes use kPa
  • Upper atmosphere measurements in kPa
  • Pressure profiling in meteorology

Engineering: Structural loads, material strength, HVAC systems.

  • Material testing: tensile strength in MPa, stress in kPa
  • Building code pressure ratings in kPa
  • Water system specifications in kPa

Additional Unit Information

About Inch of Water Column (inH₂O)

How do I convert inH₂O to PSI?

Formula: PSI = inH₂O × 0.0361273

Examples:

  • 1 inH₂O = 0.036 PSI
  • 2 inH₂O = 0.072 PSI (typical duct)
  • 5 inH₂O = 0.181 PSI
  • 10 inH₂O = 0.361 PSI (gas manifold)
  • 27.7 inH₂O = 1 PSI

inH₂O to PSI converter →

How do I convert inH₂O to Pascals or mbar?

Formula:

  • Pa = inH₂O × 249.1
  • mbar = inH₂O × 2.491

Examples:

  • 1 inH₂O = 249.1 Pa = 2.49 mbar
  • 0.5 inH₂O = 124.5 Pa = 1.25 mbar (residential duct)
  • 2 inH₂O = 498 Pa = 4.98 mbar (commercial duct)
  • 4 inH₂O = 996 Pa = 9.96 mbar (high static)

inH₂O to Pascal converter →

What is normal static pressure in HVAC?

Residential systems:

  • Total external static pressure: 0.4-0.8 inH₂O (target)
  • Supply side: 0.2-0.5 inH₂O
  • Return side: 0.1-0.3 inH₂O

High static pressure problems (>1.0 inH₂O total):

  • Reduced airflow
  • Higher energy costs
  • Shortened equipment life
  • Possible compressor damage

Low static pressure (<0.3 inH₂O):

  • May indicate oversized ductwork
  • Can cause noise issues

Commercial/Industrial: 1-4 inH₂O typical (design dependent)

When should I replace an HVAC filter?

Pressure drop method (most accurate):

  • MERV 8: Replace at 0.5 inH₂O
  • MERV 11-13: Replace at 0.7-1.0 inH₂O
  • HEPA: Replace at 2-3 inH₂O

Without gauge:

  • Monthly inspection
  • Every 1-3 months residential
  • More often if pets, allergies, construction

Measure with: Magnehelic gauge or manometer across filter

Why use inH₂O instead of PSI for HVAC?

Appropriate scale: HVAC pressures very low (0.1-2 inH₂O = 0.004-0.072 PSI) Historical: Water manometers traditional measurement tool Precision: Easier to read 0.5 inH₂O than 0.018 PSI Industry standard: ASHRAE, building codes specify inH₂O Instruments: Magnehelic gauges, manometers calibrated in inH₂O

Conversion: ~28 inH₂O = 1 PSI (HVAC uses tiny fraction of PSI)

About Kilopascal (kPa)

How do I convert kPa to PSI?

Formula: PSI = kPa × 0.145038 (or kPa ÷ 6.895)

Examples:

  • 100 kPa = 14.5 PSI
  • 200 kPa = 29 PSI (bicycle tire)
  • 220 kPa = 32 PSI (typical car tire)
  • 240 kPa = 35 PSI (SUV tire)
  • 600 kPa = 87 PSI (road bike)

kPa to PSI converter →

What is 32 PSI in kPa?

32 PSI = 220.6 kPa (standard car tire pressure)

Common tire pressures:

  • 30 PSI = 207 kPa
  • 32 PSI = 221 kPa (most common)
  • 35 PSI = 241 kPa (SUVs, loaded vehicles)
  • 40 PSI = 276 kPa (trucks, some SUVs)

PSI to kPa converter →

How many kPa in 1 bar?

1 bar = 100 kPa exactly

Examples:

  • 0.5 bar = 50 kPa
  • 1 bar = 100 kPa
  • 2 bar = 200 kPa (bicycle tire)
  • 2.5 bar = 250 kPa (car tire)
  • 10 bar = 1,000 kPa = 1 MPa

Bar to kPa converter →

Why do some countries use kPa and others PSI for tires?

kPa (kilopascal): International standard (SI unit)

  • Used in: Europe, Asia, Australia, Canada, most of world
  • Metric system, easier calculations
  • Appears on all tire sidewalls globally

PSI (pounds per square inch): US customary unit

  • Used in: United States primarily
  • Imperial system, traditional in US
  • Also appears on tire sidewalls

Dual labeling: Modern tires show both (e.g., "32 PSI / 220 kPa")

Conversion tip: Multiply kPa by 0.145 to get PSI, or divide PSI by 6.895 to get kPa

Is kPa replacing mmHg for blood pressure?

Transitioning, but slow:

mmHg still dominant: Most medical equipment, patient communication uses mmHg kPa in some regions: SI-compliant medical devices show kPa Dual display: Many modern BP monitors show both

Why slow transition?:

  • Historical familiarity (120/80 mmHg)
  • Medical education based on mmHg
  • Patient understanding
  • International guidelines still use mmHg

Conversion: 1 kPa ≈ 7.5 mmHg, so 120/80 mmHg = 16/10.7 kPa (less intuitive)

Conversion Table: Inch of Water Column to Kilopascal

Inch of Water Column (inH₂O)Kilopascal (kPa)
0.50.125
10.249
1.50.374
20.498
51.245
102.491
256.227
5012.454
10024.909
25062.272
500124.545
1,000249.089

People Also Ask

How do I convert Inch of Water Column to Kilopascal?

To convert Inch of Water Column to Kilopascal, enter the value in Inch of Water Column in the calculator above. The conversion will happen automatically. Use our free online converter for instant and accurate results. You can also visit our pressure converter page to convert between other units in this category.

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What is the conversion factor from Inch of Water Column to Kilopascal?

The conversion factor depends on the specific relationship between Inch of Water Column and Kilopascal. You can find the exact conversion formula and factor on this page. Our calculator handles all calculations automatically. See the conversion table above for common values.

Can I convert Kilopascal back to Inch of Water Column?

Yes! You can easily convert Kilopascal back to Inch of Water Column by using the swap button (⇌) in the calculator above, or by visiting our Kilopascal to Inch of Water Column converter page. You can also explore other pressure conversions on our category page.

Learn more →

What are common uses for Inch of Water Column and Kilopascal?

Inch of Water Column and Kilopascal are both standard units used in pressure measurements. They are commonly used in various applications including engineering, construction, cooking, and scientific research. Browse our pressure converter for more conversion options.

For more pressure conversion questions, visit our FAQ page or explore our conversion guides.

Helpful Conversion Guides

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⚖️ Metric vs Imperial

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All Pressure Conversions

Pascal to KilopascalPascal to MegapascalPascal to HectopascalPascal to BarPascal to MillibarPascal to AtmospherePascal to Technical AtmospherePascal to TorrPascal to Millimeter of MercuryPascal to Inch of MercuryPascal to Pound per Square InchPascal to Kilopound per Square InchPascal to Kilogram-force per Square CentimeterPascal to Kilogram-force per Square MeterPascal to Millimeter of Water ColumnPascal to Inch of Water ColumnKilopascal to PascalKilopascal to MegapascalKilopascal to HectopascalKilopascal to BarKilopascal to MillibarKilopascal to AtmosphereKilopascal to Technical AtmosphereKilopascal to TorrKilopascal to Millimeter of MercuryKilopascal to Inch of MercuryKilopascal to Pound per Square InchKilopascal to Kilopound per Square InchKilopascal to Kilogram-force per Square CentimeterKilopascal to Kilogram-force per Square MeterKilopascal to Millimeter of Water ColumnKilopascal to Inch of Water ColumnMegapascal to PascalMegapascal to KilopascalMegapascal to HectopascalMegapascal to BarMegapascal to MillibarMegapascal to AtmosphereMegapascal to Technical AtmosphereMegapascal to TorrMegapascal to Millimeter of MercuryMegapascal to Inch of MercuryMegapascal to Pound per Square InchMegapascal to Kilopound per Square InchMegapascal to Kilogram-force per Square CentimeterMegapascal to Kilogram-force per Square MeterMegapascal to Millimeter of Water ColumnMegapascal to Inch of Water ColumnHectopascal to PascalHectopascal to KilopascalHectopascal to MegapascalHectopascal to BarHectopascal to MillibarHectopascal to AtmosphereHectopascal to Technical AtmosphereHectopascal to TorrHectopascal to Millimeter of MercuryHectopascal to Inch of MercuryHectopascal to Pound per Square InchHectopascal to Kilopound per Square InchHectopascal to Kilogram-force per Square CentimeterHectopascal to Kilogram-force per Square MeterHectopascal to Millimeter of Water ColumnHectopascal to Inch of Water ColumnBar to PascalBar to KilopascalBar to MegapascalBar to HectopascalBar to MillibarBar to AtmosphereBar to Technical AtmosphereBar to TorrBar to Millimeter of MercuryBar to Inch of MercuryBar to Pound per Square InchBar to Kilopound per Square InchBar to Kilogram-force per Square CentimeterBar to Kilogram-force per Square MeterBar to Millimeter of Water ColumnBar to Inch of Water ColumnMillibar to PascalMillibar to KilopascalMillibar to MegapascalMillibar to HectopascalMillibar to BarMillibar to AtmosphereMillibar to Technical AtmosphereMillibar to TorrMillibar to Millimeter of MercuryMillibar to Inch of MercuryMillibar to Pound per Square InchMillibar to Kilopound per Square InchMillibar to Kilogram-force per Square CentimeterMillibar to Kilogram-force per Square MeterMillibar to Millimeter of Water ColumnMillibar to Inch of Water ColumnAtmosphere to PascalAtmosphere to KilopascalAtmosphere to MegapascalAtmosphere to HectopascalAtmosphere to BarAtmosphere to MillibarAtmosphere to Technical AtmosphereAtmosphere to TorrAtmosphere to Millimeter of MercuryAtmosphere to Inch of MercuryAtmosphere to Pound per Square InchAtmosphere to Kilopound per Square InchAtmosphere to Kilogram-force per Square CentimeterAtmosphere to Kilogram-force per Square MeterAtmosphere to Millimeter of Water ColumnAtmosphere to Inch of Water ColumnTechnical Atmosphere to PascalTechnical Atmosphere to KilopascalTechnical Atmosphere to MegapascalTechnical Atmosphere to HectopascalTechnical Atmosphere to BarTechnical Atmosphere to MillibarTechnical Atmosphere to AtmosphereTechnical Atmosphere to Torr

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Verified Against Authority Standards

All conversion formulas have been verified against international standards and authoritative sources to ensure maximum accuracy and reliability.

NIST Reference on Constants, Units and Uncertainty

National Institute of Standards and Technology — Fundamental physical constants and unit conversions

BIPM SI Units

Bureau International des Poids et Mesures — International System of Units (SI) definitions and standards

ISO 80000

International Organization for Standardization — Quantities and units international standards series

Last verified: February 19, 2026