Particle size distribution calculator

Inputs in the worked example

The live calculator starts with these values; change any of them and every result, check and diagram updates instantly.

Worked example — results

• ✓ Masses add up to ≤ total
• ✗ Well graded (Cu ≥ 4 G / ≥ 6 S and 1 ≤ Cc ≤ 3)

Method, formulas and assumptions

• % passing = 100 × (1 − cumulative retained / total)
• Dx by log-linear interpolation of the grading curve
• USCS: gravel vs sand split at 4.75 mm; < 5 % fines GW/GP/SW/SP, 5–12 % dual symbol, > 12 % GM/GC/SM/SC (A-line: PI = 0.73(LL − 20))
• AS 1726 uses 2.36 mm between sand and gravel; both splits are shown

Related site investigation calculators

• Specific gravity (pycnometer) — Two-trial lab sheet for soil particle density with temperature correction to 20 °C and repeatability check.
• Hydrometer analysis — Fine-fraction grading from hydrometer readings: particle diameter by Stokes' law and percent finer.
• Atterberg limits & plasticity chart — Liquid limit from cone penetrometer or Casagrande points, PI, liquidity index and position on the plasticity…
• Moisture, density & phase relations — Bulk and dry density, void ratio, porosity, saturation and field density ratio, with a three-phase diagram.
• Moisture content (oven drying) — Moisture content of several specimens from tin masses, with mean, range and repeatability check.
• Fines content by washing — Percentage finer than 75 µm from the dry mass before and after washing plus dry sieving of the residue.
• Liquid limit: cone penetrometer — Linear fit of moisture content against cone penetration; the liquid limit is w at 20 mm penetration.
• Liquid limit: Casagrande cup — Flow curve (w against log N) by least squares; LL at 25 blows and the flow index.
• Liquid limit: one-point method — LL from a single Casagrande reading using LL = wN (N/25)^0.121, valid for 20–30 blows.
• Plastic limit & consistency indices — PL from repeat threads, PI, liquidity and consistency index, activity and plasticity chart class (A-line).