Shannon Entropy
Measure uncertainty in a discrete probability distribution.
Your numbers
Entropy
Use consistent units. The result follows the assumptions you enter.
Scenario comparison
Up to three snapshots in this tab. Loading one replaces the current inputs.
Formula
Use H = −Σpᵢlog₂(pᵢ). pᵢ are probability fractions totaling unity. Zero-probability terms contribute zero. The logarithm base makes entropy H measured in bits.
Measure uncertainty in a discrete probability distribution.
Worked example
- Probabilities summing to 1
- 0.5, 0.5
- Entropy
- 1 bit
- Effective equally likely outcomes
- 2
Scope and limitations
Use consistent units. The result follows the assumptions you enter.
Inputs are checked for missing values and allowed ranges. A result outside the finite numeric range is not displayed. Rounding affects display, while the calculation uses the model’s numeric precision.
Check your units and assumptions before relying on a result. Changing a label does not convert a currency or physical unit.
Formula version: 54c4ae799ba2 · Example checked: