Examples
Examples
Try the starting example
- Phi bin representative sizes
- 0,1,2,3
- Nonnegative mass-frequency weights
- 10,20,50,20
- Weighted phi mean
- 1.8
- Weighted phi standard deviation
- 0.87178
- Moment skewness
- -0.50713
Try another scenario
- Phi bin representative sizes
- [0, 1, 2, 3]
- Nonnegative mass-frequency weights
- [20, 20, 40, 20]
- Weighted phi mean
- 1.6
- Weighted phi standard deviation
- 1.019804
- Moment skewness
- -0.271545
Calculation method
Calculation method
Weighted phi mean
sum(phi×weight)/total weight.
Weighted phi standard deviation
Population weighted second central moment square root.
Moment skewness
Weighted third central moment divided by standard deviation³; zero spread reports0.
Symbols and units
- a
- Phi bin representative sizes
- b
- Nonnegative mass-frequency weights
Use the units shown. A list keeps the order in which you enter its values. The symbol ^ means “raised to the power of”.
Calculation steps and notation
sum(list) adds all entries in the list.
Assumptions & limits
Assumptions & limits
- Method-of-moments sediment statistics from representative phi bins and mass weights. Does not claim Folk–Ward percentile statistics. Quantities are deterministic calculations from supplied observations and assumptions; no external data is fetched. Supported limits: Finite inputs only; numeric fields bounded as labelled. Lists and JSON records are limited to 256 entries unless a stricter tool bound is stated. No automatic design approval, legal conclusion, treatment recommendation or safety certification. Phi bin representative sizes: minimum None, maximum 1000000000000.0. Nonnegative mass-frequency weights: minimum 0, maximum 1000000000000.0.
Are these inputs private?
These calculations run in your browser. A shared link contains the values you choose to share. Only questions submitted to the separate AI finder are sent to OpenAI.