Calculate pressure, density, volume, area, or fluid height using weight-based ρ·V·g/A and hydrostatic ρ·g·h formulas with unit options.

Convert the supported sample weight into average pressure.

Hydrostatic results are pressure increases below the surface, assuming constant density. Weight ÷ area applies when the specified area supports the full weight. Add surface pressure separately for absolute pressure.

Optional settings

Blank uses 9.81 m/s². Enter a value to use different gravity.

Edit reference densities for actual temperature, pressure and composition.

Pressure From Density Formula

The following formula calculates average pressure when the stated area supports the full sample weight. For a constant-density fluid column, pressure increase below the surface is ΔP = ρgh; add surface pressure for absolute pressure.

Pd = D × V / A × g
  • Where Pd is the Pressure From Density (Pa)
  • D is the density (kg/m^3) 
  • V is the volume (m^3) 
  • A is the supported area (m^2); g is acceleration due to gravity (m/s^2) 

To calculate the pressure from density, multiply the density by the volume, divide by the area, then multiply by the acceleration due to gravity.

Head (V/A) to Pressure Conversion Table (Water, ρ = 1000 kg/m³, g = 9.81 m/s²)
Head h = V/A (m) Pressure (Pa) Pressure (kPa) Pressure (psi) Pressure (bar)
0.05490.50.4910.0710.005
0.10981.00.9810.1420.010
0.201962.01.9620.2840.020
0.252452.52.4530.3560.025
0.302943.02.9430.4270.029
0.504905.04.9050.7110.049
0.757357.57.3581.0670.074
1.009810.09.8101.4220.098
1.2512262.512.2631.7780.123
1.5014715.014.7152.1340.147
1.7517167.517.1682.4890.172
2.0019620.019.6202.8450.196
2.5024525.024.5253.5560.245
3.0029430.029.4304.2670.294
4.0039240.039.2405.6890.392
5.0049050.049.0507.1120.491
7.5073575.073.57510.6680.736
10.0098100.098.10014.2230.981
12.00117720.0117.72017.0681.177
15.00147150.0147.15021.3351.472
Assumes water (ρ = 1000 kg/m³) and rounded Earth gravity (g = 9.81 m/s²). For weight divided by supported area, P = ρ·V·g/A. This equals ρ·g·h for a constant-section vertical fluid column with h = V/A. Unit refs: 1 psi ≈ 6894.757293 Pa; 1 bar = 100000 Pa.

How to Calculate Pressure From Density?

The following example problems outline how to calculate the Pressure From Density.

Example Problem #1

  1. First, determine the density (kg/m^3). In this example, the density (kg/m^3) is given as 10.
  2. Next, determine the volume (m^3). For this problem, the volume (m^3) is given as  50.
  3. Next, determine the area (m^2). In this case, the area (m^2) is found to be 10.
  4. Finally, calculate the Pressure From Density using the formula above: 

Pd = D*V/ A * g

Inserting the values from above and solving yields: 

Pd = 10*50/ 10 * 9.81 = 490.5 (Pa)

Example Problem #2

Using the same method as above, determine the variables required by the equation. For this example problem, these are provided as:

density (kg/m^3) = 41

volume (m^3) = 16

area (m^2) = 28

Entering these given values yields: 

Pd = 41*16/ 28 * 9.81 = 229.83 (Pa)