Hydrostatic Pressure Calculator

    Calculate hydrostatic pressure in drilling fluids and formations using fluid density and vertical depth parameters.

    Calculation Inputs

    Pounds per gallon (ppg) or equivalent

    Vertical depth, not measured depth

    What Is Hydrostatic Pressure?

    Hydrostatic pressure is the pressure exerted by a static fluid column at a given true vertical depth (TVD). In drilling, the hydrostatic pressure of the mud column must be high enough to balance formation pressure without exceeding fracture pressure.

    Hydrostatic Pressure Formula (PPG and Feet)

    The industry-standard relationship in oilfield units is:

    P_psi = 0.052 × MW_ppg × TVD_ft

    Where:

    • P_psi = hydrostatic pressure (psi)
    • MW_ppg = mud weight (ppg)
    • TVD_ft = true vertical depth (ft)

    Example Hydrostatic Calculation

    For a 12.5 ppg mud at 10,000 ft TVD:

    P_psi = 0.052 × 12.5 × 10,000 = 6,500 psi

    Pressure Gradient and 0.052 Factor

    The constant 0.052 comes from combining:

    • Conversion between ppg and lb/ft³
    • Acceleration due to gravity
    • Unit conversions between feet and inches

    It represents the approximate pressure gradient for a 1.0 ppg fluid per foot of depth. For example, a 10.0 ppg mud has a gradient of about 0.52 psi/ft.

    Hydrostatic Pressure and Formation Pressure

    In a safe operating window:

    • Mud hydrostatic pressure should be slightly above formation pressure to prevent influx (kicks).
    • It must remain below the fracture pressure of the formation to avoid lost circulation.

    This hydrostatic pressure calculator helps quickly test different mud weights and depths against this window.

    Hydrostatic Pressure Examples

    • Example 1: 9.5 ppg mud at 8,000 ft
      P = 0.052 × 9.5 × 8,000 ≈ 3,952 psi
    • Example 2: 15.0 ppg mud at 12,000 ft
      P = 0.052 × 15.0 × 12,000 ≈ 9,360 psi

    Hydrostatic Pressure FAQ

    Does hydrostatic pressure depend on hole angle?

    Hydrostatic pressure depends on true vertical depth (TVD), not measured depth. In deviated or horizontal wells, the TVD is what controls hydrostatic pressure.

    Can I use metric units?

    Yes. When you select metric units in the calculator, the same physics apply but with a different constant. For example, pressure can be reported in kPa or bar, and density in kg/m³ or g/cm³.

    Why is hydrostatic pressure important for well control?

    If hydrostatic pressure drops below formation pressure, the well can flow and take a kick. If hydrostatic pressure is too high, the formation may fracture and lose returns. Keeping the hydrostatic pressure in the correct range is the core of safe well control.

    Related Calculators

    Mud Weight ConverterAnnular CapacityBuoyancy FactorAnnular Velocity

    Basic Formula:

    P = ρ × g × h

    Or in field units: P = 0.052 × MW × TVD

    P: Hydrostatic pressure (psi)
    MW: Mud weight or fluid density (ppg)
    TVD: True vertical depth (ft)
    0.052: Conversion constant for field units

    Get the App

    Access all calculators on the go with our mobile app

    Disclaimer: All calculators and tools provided on DrillingCalculator.com are for informational and educational purposes only. While every effort has been made to ensure accuracy, results may vary depending on input data, assumptions, and field conditions. DrillingCalculator.com makes no warranties or guarantees, expressed or implied, regarding the completeness, accuracy, or reliability of any calculation or result. Use of this site and its calculators is entirely at your own risk, and DrillingCalculator.com assumes no responsibility or liability for any decisions or outcomes based on their use.