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Inch of Water Column to Kilopound per Square Inch Converter

Convert inches of water column to kilopounds per square inch with our free online pressure converter.

Quick Answer

1 Inch of Water Column = 0.0000361 kilopounds per square inch

Formula: Inch of Water Column × conversion factor = Kilopound per Square Inch

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 Kilopound per Square Inch Calculator

How to Use the Inch of Water Column to Kilopound per Square Inch Calculator:

  1. Enter the value you want to convert in the 'From' field (Inch of Water Column).
  2. The converted value in Kilopound per Square Inch 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 Kilopound per Square Inch: Step-by-Step Guide

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

Formula:

ksi = inH₂O × 0.0000361273

Example Calculation:

1 inH₂O = 0.0000361 ksi

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.

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📋 Unit Symbols

Copy inH₂O & ksi symbols

What is a Inch of Water Column and a Kilopound per Square Inch?

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 ksi = 1,000 PSI = 6.895 MPa = 68.95 bar = 6,895 kPa = 47.88 atm

ksi = kilo-pound per square inch = 1,000 pounds-force per square inch

Also written as: KSI, 1000 PSI, 1 KPSI

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 Kilopound per Square Inch belongs to the imperial/US customary system.

Common Uses and Applications: inches of water column vs kilopounds per square inch

Explore the typical applications for both Inch of Water Column (imperial/US) and Kilopound per Square Inch (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 kilopounds per square inch

Structural Steel: Yield strength, tensile strength specifications (AISC standards). Concrete: Compressive strength testing, design specs. Materials Testing: Tensile testing, compression testing. High-Pressure Systems: Hydraulics, pressure vessels, extreme pressures.

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 Kilopound per Square Inch (ksi)

How do I convert ksi to MPa?

Formula: MPa = ksi × 6.895

Examples:

  • 36 ksi = 248 MPa (A36 steel)
  • 50 ksi = 345 MPa (A992 steel)
  • 60 ksi = 414 MPa (rebar)
  • 100 ksi = 689 MPa (high-strength)
  • 1 ksi = 6.895 MPa

ksi to MPa converter →

What does "36 ksi steel" mean?

36 ksi = yield strength of structural steel

A36 Steel (most common structural):

  • Yield strength: 36,000 PSI = 36 ksi = 248 MPa
  • Tensile strength: 58-80 ksi (ultimate strength before breaking)
  • Applications: Beams, columns, general construction

Yield strength: Stress at which permanent deformation begins Tensile strength: Maximum stress before failure

Common grades:

  • A36: 36 ksi (older standard, still common)
  • A572 Grade 50: 50 ksi (modern standard)
  • A992: 50 ksi yield (I-beams, wide flanges)

How do I convert ksi to PSI?

Formula: PSI = ksi × 1,000

Examples:

  • 1 ksi = 1,000 PSI
  • 36 ksi = 36,000 PSI (A36 steel)
  • 50 ksi = 50,000 PSI (A992 steel)
  • 4 ksi = 4,000 PSI (concrete)
  • 0.1 ksi = 100 PSI

Why use ksi?: Simpler than writing "36,000 PSI"—say "36 ksi" instead

What is typical concrete strength in ksi?

Residential/Light commercial:

  • Sidewalks, patios: 3 ksi (3,000 PSI)
  • Garage floors, driveways: 3.5-4 ksi
  • Foundation slabs: 3-4 ksi

Commercial:

  • Commercial floors: 4-5 ksi
  • Parking structures: 4-5 ksi
  • Warehouse slabs: 5-6 ksi

Structural:

  • Columns, beams: 5-8 ksi
  • High-rise buildings: 8-14 ksi
  • Bridge elements: 4-6 ksi

Special:

  • Precast prestressed: 5-10 ksi
  • Ultra-high performance: 20-30 ksi

Note: Concrete strength measured at 28 days after pouring

Why does US use ksi instead of MPa?

Historical: US construction industry established with imperial units Standards: AISC, ACI, ASTM all specify ksi Training: US engineers educated with ksi Continuity: Existing specs, calculations, tables in ksi Conversion: 1 ksi ≈ 7 MPa (approximate, easy mental math)

Rest of world: Uses MPa (SI standard)

  • 36 ksi = 248 MPa (A36 steel equivalent)
  • 50 ksi = 345 MPa (common grade)

Dual labeling: International projects often show both units

Conversion Table: Inch of Water Column to Kilopound per Square Inch

Inch of Water Column (inH₂O)Kilopound per Square Inch (ksi)
0.50
10
1.50
20
50
100
250.001
500.002
1000.004
2500.009
5000.018
1,0000.036

People Also Ask

How do I convert Inch of Water Column to Kilopound per Square Inch?

To convert Inch of Water Column to Kilopound per Square Inch, 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 Kilopound per Square Inch?

The conversion factor depends on the specific relationship between Inch of Water Column and Kilopound per Square Inch. 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 Kilopound per Square Inch back to Inch of Water Column?

Yes! You can easily convert Kilopound per Square Inch back to Inch of Water Column by using the swap button (⇌) in the calculator above, or by visiting our Kilopound per Square Inch 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 Kilopound per Square Inch?

Inch of Water Column and Kilopound per Square Inch 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.

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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