Rock/Sediment Gradation Calculator

Analyze Wolman, riprap, or calibrated-photo particle measurements to calculate D-percentiles, a percent-finer curve, sediment class, and compliance with project gradation envelopes.

Particle-size units

Existing physical-size entries are converted when units change.

Input Parameters

Measurement Method

Choose a field count or explicit measurements from a scaled photograph.

Input Method

Count Type

Particle Measurements

Enter individual intermediate-axis (b-axis) sizes in in. Commas, spaces and new lines are accepted.

Particle sizes (in)

Use one value per sampled particle. Do not enter class counts or percentages here.

0 valid particles

Gradation Specification (Optional)

Compare the measured sample with an agency/project class or a point-by-point percent-finer envelope.

Comparison Type

What this analysis reports

Characteristic sizes

D16, D30, D50, D84 and D90, plus D5/D10/D15/D60/D85/D95/D100 for specification work.

Transparent comparisons

Every entered class limit or percent-finer envelope point is shown as an individual pass/fail check.

For educational purposes only. Not a substitute for professional engineering judgment.