Skip to main content

Convert Square feet per second to Square inches per second

Instantly convert Square feet per second (ft²/s) to Square inches per second (in²/s) with our free online calculator.

Reviewed by Christopher FloiedUpdated

Formula: ft²/s to in²/smultiply by 144

Reference Table

Square feet per second (ft²/s)Square inches per second (in²/s)
1144
5720
101440
253600
507200
10014400

How to Convert Square feet per second to Square inches per second

Formula

To convert Square feet per second (ft²/s) to Square inches per second (in²/s): multiply by 144

Step-by-Step

  1. Start with your value in Square feet per second (ft²/s).
  2. Multiply by 144 to perform the conversion.
  3. The result is your value expressed in Square inches per second (in²/s).

Conversion Factor

1 ft²/s = 144 in²/s

Reverse Factor

1 in²/s = 0.00694445 ft²/s

Worked Example

Convert 25 Square feet per second to Square inches per second: 25 ft²/s = 3600 in²/s

About Square foot per second (ft²/s)

An imperial unit of kinematic viscosity equal to ≈ 0.092903 m²/s = 92,903 cSt per NIST SP 811. Ft²/s is a very large unit — appropriate for gaseous and highly mobile fluids but unwieldy for common liquids (water at 20 °C is only 1.08 × 10⁻⁵ ft²/s, which is essentially zero on a normal scale). Primarily encountered in: pre-1990s US-edition fluid-mechanics textbooks (Streeter, Roberson-Crowe, Olson) where the entire problem set is in lb-ft-s units to keep dimensional analysis clean; older US petroleum engineering pipeline-flow literature; and some US Bureau of Reclamation hydraulics publications. Reference values: air at 60 °F ~1.6 × 10⁻⁴ ft²/s; standard atmospheric air at 32,000 ft (jetliner cruise altitude) ~5.5 × 10⁻⁴ ft²/s. Convert ft²/s to m²/s by multiplying by 0.0929; to cSt by multiplying by 92,903.

About Square inch per second (in²/s)

An imperial kinematic-viscosity unit equal to ≈ 6.4516 × 10⁻⁴ m²/s = 645.16 cSt (= 1/144 of ft²/s, since 1 ft² = 144 in²) per NIST SP 811. in²/s is a specialty unit used in some US mechanical-engineering contexts where ft²/s would be inconveniently large and cSt is the industry standard. Common in: older US hydraulic-fluid specifications (MIL-PRF-83282 fire-resistant hydraulic fluid, MIL-PRF-87257 low-temperature hydraulic fluid, and other US military-spec hydraulic fluid TSDs sometimes dual-list viscosity in cSt and in²/s); US aerospace bearing lubricant specifications (Pratt & Whitney and GE Aviation engine-oil specs); and pre-1990s US-edition machine-design textbooks where bearing-design problems were worked entirely in in / lbf / s. Most modern US engineering has converged on cSt and mPa·s. Convert in²/s to cSt by multiplying by 645.16; to m²/s by multiplying by 6.452 × 10⁻⁴.

Quick Facts

  • 1 Square foot per second equals 144 Square inches per second
  • 1 Square inch per second equals 0.00694445 Square feet per second
  • Square foot per second is a unit of kinematic viscosity
  • Square inch per second is a unit of kinematic viscosity
  • This conversion is commonly used in fluid flow analysis, lubrication engineering, and process design
  • The Square foot per second belongs to the imperial system

Common Square foot per second to Square inch per second Conversions

Square feet per second (ft²/s)Square inches per second (in²/s)
0.011.44
0.114.4
0.2536
0.572
1144
2288
3432
5720
101440
152160
202880
253600
507200
7510800
10014400
25036000
50072000
1000144000
5000720000
100001440000

Understanding Square feet per second

The Square foot per second (symbol: ft²/s) is a unit of kinematic viscosity. An imperial unit of kinematic viscosity equal to ≈ 0.092903 m²/s = 92,903 cSt per NIST SP 811. Ft²/s is a very large unit — appropriate for gaseous and highly mobile fluids but unwieldy for common liquids (water at 20 °C is only 1.08 × 10⁻⁵ ft²/s, which is essentially zero on a normal scale). Primarily encountered in: pre-1990s US-edition fluid-mechanics textbooks (Streeter, Roberson-Crowe, Olson) where the entire problem set is in lb-ft-s units to keep dimensional analysis clean; older US petroleum engineering pipeline-flow literature; and some US Bureau of Reclamation hydraulics publications. Reference values: air at 60 °F ~1.6 × 10⁻⁴ ft²/s; standard atmospheric air at 32,000 ft (jetliner cruise altitude) ~5.5 × 10⁻⁴ ft²/s. Convert ft²/s to m²/s by multiplying by 0.0929; to cSt by multiplying by 92,903.

It belongs to the imperial measurement system.

Square feet per second are commonly used in fluid flow analysis, lubrication engineering, and process design.

Understanding Square inches per second

The Square inch per second (symbol: in²/s) is a unit of kinematic viscosity. An imperial kinematic-viscosity unit equal to ≈ 6.4516 × 10⁻⁴ m²/s = 645.16 cSt (= 1/144 of ft²/s, since 1 ft² = 144 in²) per NIST SP 811. in²/s is a specialty unit used in some US mechanical-engineering contexts where ft²/s would be inconveniently large and cSt is the industry standard. Common in: older US hydraulic-fluid specifications (MIL-PRF-83282 fire-resistant hydraulic fluid, MIL-PRF-87257 low-temperature hydraulic fluid, and other US military-spec hydraulic fluid TSDs sometimes dual-list viscosity in cSt and in²/s); US aerospace bearing lubricant specifications (Pratt & Whitney and GE Aviation engine-oil specs); and pre-1990s US-edition machine-design textbooks where bearing-design problems were worked entirely in in / lbf / s. Most modern US engineering has converged on cSt and mPa·s. Convert in²/s to cSt by multiplying by 645.16; to m²/s by multiplying by 6.452 × 10⁻⁴.

It belongs to the imperial measurement system.

Square inches per second are commonly used in fluid flow analysis, lubrication engineering, and process design.

Why Convert Square feet per second to Square inches per second?

Converting between Square feet per second and Square inches per second is a frequent requirement for engineers, scientists, and students working with kinematic viscosity values. Different industries and regions favour different unit systems, so having a dependable conversion tool saves time and prevents errors in technical calculations. Whether you are verifying a specification sheet, cross-checking simulation results, or preparing a report for an international audience, accurate kinematic viscosity conversion is essential.

Frequently Asked Questions

How do I convert Square feet per second to Square inches per second?

An imperial unit of kinematic viscosity equal to ≈ 0. To convert Square feet per second to Square inches per second, multiply by 144. For example, 25 ft²/s equals 3600 in²/s.

How many Square inches per second are in 1 Square foot per second?

There are 144 Square inches per second in 1 Square foot per second.

How many Square feet per second are in 1 Square inch per second?

There are 0.00694445 Square feet per second in 1 Square inch per second.

What is the formula for Square foot per second to Square inch per second conversion?

The formula is: multiply by 144. This means 1 ft²/s = 144 in²/s.

Is a Square foot per second bigger than a Square inch per second?

No. One Square foot per second is smaller than one Square inch per second because 1 ft²/s equals 144 in²/s, which is greater than 1.

When do you need to convert between Square feet per second and Square inches per second?

An imperial kinematic-viscosity unit equal to ≈ 6. Square foot per second and Square inch per second are both kinematic viscosity units, so conversion comes up whenever one source of information uses one unit and another uses the other — a classic cross-reference challenge in engineering, trade, travel, and everyday life.

More Kinematic Viscosity Conversions

Related Tools