How to use the sediment grain size phi scale calculator
Convert a sediment grain diameter into the phi scale and the Wentworth size class. Enter grain diameter in the field above; the phi grain size, wentworth size class are computed instantly and plotted on the chart so you can see how the answer changes.
Common searches this calculator answers include “grain size phi”, “sediment size class”, “Wentworth scale calculator”, “calculate sediment grain size phi scale”, “find phi grain size”.
Formula
Variables
- d — Grain diameter (mm)
Worked example
With grain diameter = 0.5 mm, the calculator gives phi grain size ≈ 1 φ; wentworth size class ≈ Sand text.
Frequently asked questions
What is the sediment grain size phi scale calculator used for?
Convert a sediment grain diameter into the phi scale and the Wentworth size class. It helps with questions such as “grain size phi”, “sediment size class”, “Wentworth scale calculator”.
What is the formula for the sediment grain size phi scale calculation?
Phi grain size (φ) = -log2(d). Wentworth size class (text) = d>2?"Gravel":(d>0.0625?"Sand":"Silt or clay"). Here d is grain diameter (mm).
What inputs do I need for the sediment grain size phi scale calculator?
You need grain diameter in mm. Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use the sediment grain size phi scale calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the sediment grain size phi scale result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.