1,000 N spread over 0.02 m²
P = F ÷ A
1,000 N ÷ 0.02 m² gives 50,000 Pa, or 50 kPa. Applying that same force over twice the area would halve the average pressure.
Force & area
Pressure Calculator
Find pressure, normal force, or area from the other two quantities, with metric and customary units.
Calculate pressure, normal force, or area
Pressure
Enter two positive quantities, then select Calculate.
- SI equivalent
- Formula
Calculation steps
≈ marks display rounding. Calculations run in your browser. Press Enter to calculate. Successful results appear in this tab's Recent calculations.
Three ways to use the pressure formula
250 kPa acting over 40 cm²
F = P × A
Convert 250 kPa to 250,000 Pa and 40 cm² to 0.004 m². Their product is 1,000 N, or 1 kN.
120 lbf at 30 psi
A = F ÷ P
A psi is one pound-force per square inch. Dividing 120 lbf by 30 lbf/in² gives 4 in², or exactly 0.00258064 m².
Units, assumptions, and rounding
Pressure is normal force per area. The force must act perpendicular to the surface; a tangential force is not included. The SI unit is the pascal: 1 Pa = 1 N/m². If the load is not uniform, total normal force divided by area gives the average pressure.
This tool uses positive magnitudes and a flat surface. Use a uniform pressure, or the appropriate average over that surface, when finding force. It does not integrate varying pressures, resolve angled forces, or add forces acting on differently oriented surfaces.
1 kPa = 1,000 Pa, 1 MPa = 1,000,000 Pa, 1 bar = 100,000 Pa, and 1 standard atmosphere (atm) = 101,325 Pa, all exactly. The atm unit is a defined scale; it does not supply a reading of local atmospheric pressure.
The international definitions are 1 in = 0.0254 m and 1 ft = 0.3048 m. Area conversions square those lengths. A pound-force is exactly 4.4482216152605 N, based on a mass of 0.45359237 kg and standard gravity of 9.80665 m/s². One psi is exactly 1 lbf/in²; its pascal conversion is calculated from those definitions without a shortened decimal factor.
All active inputs must be positive, with at most 64 characters, 15 integer digits, and 10 decimal places. Numeric fields do not accept expressions, scientific notation, or embedded units. An inactive field does not affect the answer.
The calculation retains exact fractions through conversion and arithmetic. Only the final display is rounded; halfway values round away from zero. Trailing zeros are omitted. ≈ marks rounding, including a positive result that displays as zero. Changing the result unit or display precision does not add a recent-calculation entry. Display digits do not increase measurement accuracy.
References: OpenStax — pressure and normal force, NIST Guide to the SI — conversion factors, and NIST — exact pound-force definition.
Common questions
Does this convert gauge pressure to absolute pressure?
No. Gauge pressure is measured relative to a surrounding pressure; absolute pressure uses a vacuum reference. This calculator only converts units and applies P = F/A. For the net force from pressures on opposite sides of a surface, enter their positive difference. It does not infer or add atmospheric pressure.
Can I enter kilograms or pounds as a force?
Not as mass values. Kilograms and pounds of mass must be multiplied by the relevant gravitational acceleration to obtain weight force. Enter force in newtons, kilonewtons, or pound-force. The lbf unit uses the standard-gravity definition; it is not a local gravity measurement.
Why are zero and negative values excluded?
This tool solves for positive magnitudes. Zero area makes F/A undefined; zero pressure can prevent a unique area solution. Zero or negative gauge pressures can be meaningful in other models, but signed pressures and vacuum calculations are outside this tool's scope.
Can this find pressure at a water depth?
Not from depth alone. Hydrostatic pressure depends on density, gravity, depth, and a reference pressure. This calculator needs two of pressure, normal force, and area. It does not calculate hydrostatic, gas-law, or temperature effects.
Why does a small positive result show ≈ 0?
The number is smaller than the selected display precision can show. Choose more decimal places or another result unit. The stored calculation remains positive and unrounded.