Probability Calculator
Calculate simple probability from favorable and total outcomes.
About this tool
This tool calculates a simple probability when outcomes are treated as equally likely. Enter the number of favourable outcomes and the total possible outcomes to express the probability as a percentage.
How to use this calculator
- Enter the number of favourable outcomes.
- Enter the total number of possible outcomes, which must be greater than zero.
- Calculate the percentage and check that favourable outcomes do not exceed total outcomes.
Formula
Worked example
For one favourable outcome among six equally likely outcomes: 1 ÷ 6 × 100 ≈ 16.67%.
Frequently asked questions
What is probability?
Probability describes how likely an event is. It ranges from 0% for an impossible event to 100% for a certain event.
When does favourable outcomes divided by total outcomes work?
It works for a finite set of equally likely outcomes, such as a fair die. If outcomes have different chances, a simple count may not represent the true probability.
Can probability be more than 100%?
No. For valid counts, favourable outcomes must be between zero and the total number of outcomes.
What if total outcomes is zero?
The calculation is undefined because it requires division by the total. Enter a positive total and verify the counts.
EzCalcTools provides general calculations for information and planning. Results depend on the values and assumptions entered. For financial, investment, payroll or tax decisions, confirm the applicable product terms and current rules with an authoritative source or qualified professional.