Geology Calculators
Darcy Flow Velocity Calculator
Calculate Darcy velocity (specific discharge) of groundwater flow from hydraulic conductivity and hydraulic gradient using Darcy's Law.
Effective Stress Calculator
Calculate effective stress from total stress and pore water pressure using Terzaghi's foundational principle of soil mechanics.
Fault Slip Rate Calculator
Calculate a faults long-term average slip rate from total displacement and elapsed time, a key input for seismic hazard and earthquake recurrence estimates.
Geothermal Gradient Calculator
Calculate the geothermal gradient in degrees per kilometer from surface temperature, temperature at depth, and depth measurement.
Grain Size Phi Calculator
Convert sediment grain diameter in millimeters to the Krumbein phi scale used throughout sedimentology for grain size classification.
Hydraulic Gradient Calculator
Calculate hydraulic gradient from head difference and flow path length, the driving force behind groundwater flow.
Mineral Hardness Calculator
Look up any mineral on the standard Mohs hardness scale, from Talc at 1 to Diamond at 10, for quick field identification of an unknown mineral specimen.
Mineral Specific Gravity Calculator
Calculate a mineral's specific gravity from its weight in air and weight in water using the classic hydrostatic weighing technique.
Permeability Calculator
Calculate the permeability coefficient of a geologic material from flow rate, area, pressure difference, fluid viscosity, and length, using Darcys Law.
Pore Water Pressure Calculator
Calculate hydrostatic pore water pressure at a given depth below the water table, a key input for effective stress and slope stability analysis.
Porosity Calculator
Calculate rock or soil porosity from void and total volume, or from bulk and particle density, and compare your result to typical material porosity ranges.
Radiometric Age Calculator
Calculate radiometric age from a remaining isotope fraction or a parent-daughter ratio combined with a known half-life, using the standard decay equation.
Rock Density Calculator
Calculate rock or mineral density from mass and volume, then compare your result against typical published density ranges for common rock types.
Rock Quality Designation Calculator
Calculate Rock Quality Designation (RQD) percentage from drill core samples to assess rock mass quality for tunneling and foundation engineering.
Rock Volume Calculator
Calculate the volume of a rock or core sample as a cube, rectangular block, or cylinder, the starting point for later density and porosity calculations.
Seismic Magnitude Calculator
Convert earthquake magnitude to energy released in Joules, or work backward from energy to magnitude, using the standard Gutenberg-Richter energy relation.
Soil Bearing Capacity Calculator
Estimate ultimate soil bearing capacity using the Terzaghi equation, with bearing capacity factors interpolated from the standard published Terzaghi table.
Soil Void Ratio Calculator
Calculate soil void ratio from void volume and solid volume, the standard geotechnical engineering measure of pore space.
Stokes Settling Velocity Calculator
Calculate the terminal settling velocity of a sediment particle in fluid using Stokes' Law from particle size, density, and fluid properties.
Stratigraphic Thickness Calculator
Convert an apparent field bed thickness into true stratigraphic thickness using the dip angle cosine correction, essential for accurate stratigraphic columns.
Reading the Ground Beneath Everything
Rock, soil, and seismic activity all carry measurable properties — density, hardness, permeability, magnitude — that geologists rely on for everything from foundation design to earthquake risk assessment. These ten calculators cover that quantitative side of geology.
Why One Richter Number Is a Very Big Jump
This is why a magnitude 7 earthquake is not "a bit worse" than a magnitude 5 — it releases roughly a thousand times more energy, which is also why magnitude scales use whole and half numbers rather than the much larger raw energy figures directly. Check the math with the Seismic Magnitude Calculator.
Popular Geology Calculators
- Rock Density Calculator — calculates density from a rock sample's mass and volume.
- Porosity Calculator — estimates the void space fraction in rock or soil, relevant to groundwater and oil reservoir capacity.
- Radiometric Age Calculator — estimates a sample's age from radioactive isotope decay measurements.
Related: Civil Engineering Calculators for soil bearing capacity in construction contexts, Chemistry Calculators for the underlying decay math.