Calculator
Hydrostatic Pressure Calculator
Uses the standard formula HP = 0.052 × MW × TVD. Compares your result against pore and fracture pressure to flag kick or lost-circulation risk.
⚙ Hydrostatic Pressure
Hydrostatic Pressure—
Pore Pressure—
Fracture Pressure—
Overbalance—
Drilling Status—
Not sure what to enter? Freshwater pore pressure gradient ≈ 0.433 psi/ft. Seawater ≈ 0.445 psi/ft. A typical fracture gradient in normally pressured formations runs 0.7–0.85 psi/ft but varies significantly by basin and depth — always use actual leak-off test (LOT) data for real operations.
How This Calculator Works
This tool applies the standard hydrostatic pressure formula used throughout the drilling industry:
Hydrostatic Pressure
HP (psi) = 0.052 × MW (ppg) × TVD (ft)
0.052 is the unit conversion constant relating pounds per gallon and feet to psi.
It then compares your hydrostatic pressure against the pore pressure and fracture pressure at the same depth (calculated from the gradients you enter) to determine whether your mud weight sits safely inside the mud weight window.
Reading Your Results
- Safe Drilling Window — hydrostatic pressure is comfortably between pore and fracture pressure.
- Very Low Overbalance — under 100 psi margin above pore pressure. Kick risk if pressure fluctuates.
- High Overbalance — over 1,500 psi margin. Watch ECD carefully; risk of formation damage or differential sticking.
- Underbalanced / Overbalanced (critical) — hydrostatic pressure has crossed pore or fracture pressure entirely. Immediate review required.
For full formula derivations and worked examples, see the mud weight and pressure reference page. If you're working through an active kick, use the kill sheet calculator instead.