Use this geological calculation for a transparent first-pass interpretation of measured rock, soil, fluid, well, stratigraphic, isotopic, geophysical, or seismic data under an explicitly selected model.

g obs

Observed absolute gravity at the station in milligal.

Elevation

Station elevation above the datum in meters.

g ref

Theoretical (normal) gravity at the station latitude and datum in milligal.

Land free-air anomaly in milligal: g_obs - g_ref + 0.3086 h with station elevation h in meters and the standard free-air gradient of 0.3086 milligal per meter. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Free-air anomaly

Free-air anomaly in milligal.

Free-air correction

Free-air correction 0.3086 h in milligal.

• Classification diagrams and geochemical ratios require appropriate normalization, oxidation-state treatment, volatile basis, analytical quality, alteration screening, mineral or whole-rock context, and a composition within the method's calibration domain.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Compare independent measurements and models, retain units and analytical metadata, propagate uncertainty, and validate interpretations against logs, cores, maps, laboratory data, or field observations.

• Gravity Anomaly Bouguer Calculator

  Land Bouguer anomaly in milligal: g_obs - g_ref + 0.3086 h - 2 pi G rho h, with elevation h in meters and reduction density rho in kilograms per cubic meter (default 2670 kg/m^3).

• Darcy Discharge Calculator

  Compute the total Darcy flow discharge in cubic meters per second as hydraulic conductivity times gradient times cross-sectional area.

• Darcy Velocity Calculator

  Compute the Darcian specific discharge velocity in meters per second as hydraulic conductivity times hydraulic gradient.