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Geotechnical Toolbox

Units & Reference

Geotechnical Unit Converter

Convert geotechnical units: pressure (kPa, psf, tsf), unit weight (kN/m³, pcf), hydraulic conductivity, cv, force, moment, subgrade modulus, flow and slope.

NIST SP 811ASTM SI 10

Inputs

Demo

1. Quantity

2. Value to Convert

Water heads use the conventional density of 1000 kg/m³ and standard gravity. tsf is the US short ton (2000 lbf) per ft²; t/m² is the metric tonne-force per m².

Results

Pick a quantity and enter a value above, or click a Demo preset, to see it in every unit.

Common Geotechnical Conversions

Pressure
1 tsf = 95.76 kPa ≈ 1 kgf/cm² ≈ 1 bar
Pressure
1 ksf = 47.88 kPa; 1 psf = 0.04788 kPa
Pressure
1 psi = 6.895 kPa; 100 kPa = 2.089 ksf = 14.50 psi
Unit weight
1 kN/m³ = 6.366 pcf; 100 pcf = 15.71 kN/m³
Unit weight
Water: 9.81 kN/m³ = 62.4 pcf
Density
1 Mg/m³ = 1 g/cm³ = 62.43 lb/ft³ → γ = 9.81 kN/m³
Conductivity
1 cm/s = 10⁻² m/s = 864 m/day = 2835 ft/day
Conductivity
1 m/s ≈ 1.04 × 10⁵ darcy (water, 20 °C)
Consolidation
1 m²/yr = 3.169 × 10⁻⁸ m²/s = 10.76 ft²/yr
Line load
1 kip/ft = 14.59 kN/m; 1 kN/m = 68.52 lbf/ft
Moment
1 kip·ft = 1.356 kN·m; 1 kip·ft/ft = 4.448 kN·m/m
Subgrade modulus
1 pci = 271.4 kN/m³; 1 MN/m³ = 3.684 pci
Section modulus
1 in³/ft = 53.76 cm³/m
Acceleration
1 g = 9.807 m/s² = 980.7 Gal = 32.17 ft/s²

Theory and formulae

Definitions Used

About this calculator

This free unit converter calculator runs entirely in your browser: what you enter is never uploaded. Use the calculation steps and the theory section to check the working, and print a calculation sheet with the inputs, results and formulae for your records.

Methods and references: NIST SP 811, ASTM SI 10.

Topics: unit converter, kpa to psf, kpa to tsf, ksf, kn/m3 to pcf, hydraulic conductivity, permeability units, darcy, coefficient of consolidation, subgrade modulus, pci, slope percent, imperial to metric.

Engineering notice: Results are for preliminary estimation, screening and education. All inputs and outputs must be independently verified by a qualified professional engineer before use in any design or construction decision. Read the full disclaimer