Probability Calculator
Your entries are calculated in this browser and are not saved by this tool.
How the Probability Calculator works
Calculate a simple event probability, complement and repeated independent trials. Enter the requested values in the tool above, select Calculate, and review both the main result and its breakdown.
Formula used
P(event) = favorable÷total. Complement = 1−P. P(event in every independent trial) = P^trials.
Worked example
Rolling a specific face on a fair six-sided die has probability 1/6, or about 16.67%.
Practical uses
- Model a simple event
- Find the complement
- Estimate repeated independent outcomes
Assumptions and limits
Results depend on the supplied values and displayed rounding. For reproducibility, record the inputs and assumptions used when sharing a result.
Frequently asked questions
Is this calculator free?
Yes. It can be used without creating an account.
Are the values I enter stored?
The calculation runs in your browser. The core tool does not submit your calculator entries to WordPress.
Can I rely on the result for a major decision?
Use it as an educational estimate, verify important inputs, and seek qualified advice when the decision carries financial, medical, tax or legal consequences.