PSF to PSI Pressure Converter

Pressure Value

Input Unit

Result

psf (lb/ft²)

psi (lb/in²)

Pascals (Pa)

kPa

bar

atm

Conversion Applied

How Pressure Unit Conversion Works

The PSF to PSI Pressure Converter takes a pressure value in any unit and outputs it instantly in all six common pressure units: pounds per square foot (psf), pounds per square inch (psi), Pascals (Pa), kilopascals (kPa), bar, and atmospheres (atm). This is particularly useful in structural engineering, HVAC, and fluid mechanics, where different disciplines use different standard units.

What Is PSF (Pounds per Square Foot)?

Pounds per square foot (psf) is a pressure unit equal to the force of one pound-force applied over one square foot of area. It is used primarily in structural engineering and building design in the United States, where floor load capacities, soil bearing pressures, and roof snow loads are routinely specified in psf. Standard atmospheric pressure equals approximately 2,116 psf. One psf equals 47.88 Pascals.

What Is PSI (Pounds per Square Inch)?

Pounds per square inch (psi) is a pressure unit equal to the force of one pound-force over one square inch. Because a square foot contains 144 square inches, 1 psi = 144 psf. PSI is used in the US and UK for tyre pressure (typically 30–35 psi for passenger cars), hydraulic system pressure (500–3,000 psi for industrial systems), and gas cylinder pressure. Standard atmospheric pressure is approximately 14.696 psi.

SI and Other Pressure Units

The Pascal (Pa) is the SI unit of pressure, defined as one Newton per square metre (1 N/m²). The Pascal is very small — standard atmospheric pressure equals 101,325 Pa (101.325 kPa). The bar is defined as exactly 100,000 Pa (100 kPa) and is commonly used in meteorology and industrial pressure measurement. One atmosphere (atm) is defined as exactly 101,325 Pa and represents standard sea-level air pressure.

PSF to PSI Conversion Formula

PSI = PSF ÷ 144

Or via Pascals (base unit):
1 psf = 47.880 Pa
1 psi = 6,894.76 Pa
1 kPa = 1,000 Pa
1 bar = 100,000 Pa
1 atm = 101,325 Pa

Example: A structural floor rated at 250 psf: PSI = 250 ÷ 144 = 1.736 psi = 250 × 47.88 = 11,970 Pa = 11.97 kPa = 0.1197 bar.

The calculator handles this automatically — the formula is shown here for transparency.

Pressure Unit Reference Table

Situation	Pressure	Unit
Standard atmospheric pressure	14.696	psi (2,116 psf)
Car tyre (typical)	30–35	psi
Office floor load capacity	50–100	psf
Bicycle tyre	80–130	psi
Hydraulic press (industrial)	1,000–3,000	psi
Deep ocean (11,000 m)	~15,900	psi (~1,086 atm)

Frequently Asked Questions

How do you convert PSF to PSI?

Divide psf by 144: PSI = PSF ÷ 144. Since there are 144 square inches in a square foot (12 × 12), a force spread over a square foot creates 144 times less pressure per square inch. For example, 2,880 psf ÷ 144 = 20 psi.

What is the difference between PSF and PSI?

Both measure pressure (force per unit area) using pound-force, but over different areas. PSI uses a square inch (1 in²); PSF uses a square foot (144 in²). PSI is used for smaller, higher-pressure contexts (tyres, pipes); PSF is used for larger structural loads (floors, soil). 1 psi = 144 psf.

What does a pressure result in Pascals mean in everyday terms?

One Pascal is a very small pressure — roughly the pressure of a US dollar bill lying flat on a table. Standard atmospheric pressure at sea level is 101,325 Pa (approximately 101 kPa or 1.01 bar). A car tyre at 30 psi is inflated to approximately 206,843 Pa above atmospheric pressure (gauge pressure), or about 308,000 Pa absolute.

When should I use bar instead of kPa or psi?

Bar is common in European and international industrial pressure specifications, particularly for compressed air systems, diving equipment, and high-pressure hydraulics. 1 bar = 100 kPa ≈ 14.5 psi. For contexts where metric units are preferred but kPa produces unwieldy large numbers (e.g., "10 bar" is cleaner than "1,000 kPa"), bar is the practical choice. In meteorology, atmospheric pressure is often reported in millibars (mbar), where 1 mbar = 100 Pa.

What is a typical floor load in psf for residential buildings?

Residential floors in the US are typically designed for a live load of 40 psf (1,915 Pa) for bedrooms and 50 psf (2,394 Pa) for living areas, per the International Building Code (IBC). Office floors are designed for 50–80 psf (2,394–3,831 Pa). Heavy-duty industrial floors may be specified at 250–500 psf or more for forklift and storage loads.

How accurate is this pressure conversion calculator?

All pressure conversions in this calculator are based on exact defined relationships: 1 psi = exactly 6,894.757 Pa; 1 psf = exactly 47.880 Pa; 1 bar = exactly 100,000 Pa; 1 atm = exactly 101,325 Pa. The conversions are mathematically exact (within floating-point arithmetic). The only source of error is in the input value itself.

Is gauge pressure or absolute pressure being calculated here?

This calculator converts between pressure units without distinguishing gauge and absolute pressure — it treats the entered value as a magnitude. In engineering, gauge pressure is measured relative to atmospheric pressure (a car tyre "at 30 psi" means 30 psi above atmospheric); absolute pressure includes atmospheric pressure. If you enter a gauge pressure in psi, the converted values are also gauge pressures. Add 14.696 psi (101.325 kPa) to convert gauge to absolute.

Why are there so many pressure units in use?

Pressure measurement developed independently in different fields and countries, each adopting the unit most convenient for their context. Structural engineers in the US work with loads in psf (building codes specify floor loads in psf); fluid engineers use psi or bar; meteorologists use millibars or hectopascals (hPa, equivalent to mbar); physicists use Pascals; the medical field uses millimetres of mercury (mmHg) for blood pressure. The variety reflects specialised origins rather than a consistent international standard for all applications.