Geology Calculators
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.
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.
Permeability Calculator
Calculate the permeability coefficient of a geologic material from flow rate, area, pressure difference, fluid viscosity, and length, using Darcys Law.
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 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.
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 Numbers Locked Inside Rock
Geology turns physical rock samples and field measurements into numbers that reveal history and structure — a radiometric age calculation reaching back millions of years, a porosity measurement predicting how much water or oil a rock formation can hold, a seismic magnitude describing energy released in an earthquake. Ten calculators here cover the formulas behind that translation.
Popular Geology Calculators
Ten tools span dating, rock properties, and seismic measurement:
- Radiometric Age Calculator — estimates a sample's age from the decay of a radioactive isotope and its known half-life.
- Porosity Calculator — finds the percentage of void space in a rock sample, key for groundwater and petroleum reservoir estimates.
- Rock Density Calculator — calculates density from a rock sample's mass and volume.
- Seismic Magnitude Calculator — estimates earthquake magnitude from seismic wave measurements.
- Permeability Calculator — estimates how easily fluid moves through a rock or soil formation.
Why the Richter Scale Isn't as Simple as It Looks
Earthquake magnitude scales are logarithmic, not linear — each whole-number increase represents roughly 10 times greater ground motion and about 32 times more energy released, which is why a magnitude 7 earthquake isn't just "a bit stronger" than a magnitude 6, it releases dramatically more energy. This is the same reason radiometric dating uses half-life math rather than a simple linear decay rate: radioactive decay follows an exponential curve, so the proportion of parent isotope remaining after one half-life, two half-lives, and three half-lives shrinks by half each time rather than by a constant amount.
Frequently Asked Questions
Why do geologists use different isotopes for different age ranges?
Each radioactive isotope has a different half-life, so carbon-14 (half-life ~5,730 years) works for dating recent organic material, while uranium-lead (half-life in billions of years) is needed for dating much older rock formations.
Does high porosity always mean high permeability?
No — porosity measures total void space, while permeability measures how well those voids are connected; a rock can have high porosity but low permeability if its pores are isolated rather than interconnected.
Explore More
Interested in surface-level earth features instead? See the Geography Calculators, or check structural applications in the Civil Engineering Calculators.