Grain Size Distribution Curve Plotter — Sieve Analysis Online
Paste sieve sizes and percent passing and get a semi-logarithmic particle-size distribution curve, with D10, D30, D60, Cu and Cc calculated for you. Free, in the browser, nothing uploaded.
What the grain size distribution curve shows
A particle-size distribution curve plots percent passing on a linear vertical axis against particle diameter on a logarithmic horizontal axis, with diameter increasing to the left in the conventional layout. The logarithmic axis is not decoration: a soil routinely spans from 75 mm gravel down to 0.001 mm clay, five orders of magnitude, and no linear axis can show that range and still resolve the fines.
The data come from two tests joined into one curve. Sieve analysis (ASTM D6913 / BS 1377-2) covers everything coarser than the 75 µm sieve by washing and shaking a dried sample through a nest of sieves and weighing each retained fraction. Below 75 µm the particles will not sieve, so the fines are measured by hydrometer (ASTM D7928) using Stokes' law to convert settling velocity into an equivalent spherical diameter. A well-run test produces a single continuous curve across the join.
Data
Paste straight from Excel or Google Sheets — include the header row and the columns are matched by name, in any order.
| # | Sample(opt) | Sieve sizemm | Passing% | LL%(opt) | PL%(opt) | |
|---|---|---|---|---|---|---|
| 1 | ||||||
| 2 | ||||||
| 3 | ||||||
| 4 |
0 rows of data
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Export gradation curve + plasticity chart
Renders the gradation curve from the table above, plus a Casagrande plasticity chart from the same samples’ LL and PL values, and downloads both as one zip.
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D10, D30, D60, Cu and Cc
D₁₀, D₃₀ and D₆₀ are read off the curve, not measured: D₆₀ is the particle diameter at which 60% of the sample by mass is finer. D₁₀ is called the effective size because it controls permeability far more than the mean size does — the fine fraction throttles flow through the pore throats. Hazen's old approximation k ≈ C·D₁₀² (with D₁₀ in mm and k in cm/s) is still a useful order-of-magnitude sanity check for clean sands.
The two shape numbers follow from those readings. The coefficient of uniformity Cu = D₆₀/D₁₀ measures how wide the range of sizes is: a value near 1 is a single-size (uniform) soil, a large value is a broadly graded one. The coefficient of curvature Cc = D₃₀²/(D₁₀·D₆₀) measures whether the curve is smooth or has a gap in the middle. Under the USCS a gravel is well graded when Cu ≥ 4 and 1 ≤ Cc ≤ 3; a sand needs Cu ≥ 6 with the same Cc window. Fail either and the soil is poorly graded — either uniform, or gap-graded with a missing size fraction.
This matters because well-graded material compacts to a denser, stronger, less permeable fill: the small particles occupy the voids between the large ones. Poorly graded material has more void space, lower density and higher permeability — sometimes exactly what you want, if you are specifying a drainage layer or a filter.
Who uses one
Geotechnical engineers classifying soils under the USCS or AASHTO, specifying fill and checking it on site, and designing filters and drainage blanks against piping. Civil engineering students working through a soil-mechanics lab. Hydrogeologists estimating aquifer permeability from borehole samples. Sedimentologists describing sorting, and dam and coastal engineers specifying rock armour and beach nourishment.
Common questions
- Do I enter sieve aperture or the retained mass?
- Sieve aperture in millimetres and cumulative percent passing. Convert retained masses to cumulative percent passing first — that is the quantity the curve is defined on, and it is what a lab sheet normally reports anyway.
- How are D10, D30 and D60 interpolated?
- By linear interpolation between the two bracketing points on the log-diameter axis, which is the standard reading convention. If your finest data point is coarser than 10% passing, D₁₀ cannot be read and Cu and Cc are undefined rather than guessed.
- Can I plot more than one sample?
- Yes. Give each set of points a sample name in the first column and each one is drawn as its own curve, which is how a grading envelope for a specification is normally presented.
- What are the liquid and plastic limit columns for?
- They are optional. Full USCS classification of a soil with more than 5% fines needs the Atterberg limits as well as the grading, so supplying them lets one table produce both the curve and the group symbol. For the chart itself, use the plasticity chart.