Probability Calculator
Use exact integer counts for combinations and permutations, or enter bounded probabilities for simple and independent events. All calculations run locally.
A QUICK WALKTHROUGH
How to use this tool
- Choose a calculation type.
- Enter values within the stated bounds.
- Calculate and review the formula and result.
Scope and assumptions
Combinations and permutations use sampling without replacement. Basic probability is favorable outcomes divided by total outcomes. AND and OR use independent-event formulas; OR is not a general dependent-event union calculator.
Local calculation
All arithmetic runs in your browser. Inputs are bounded to keep exact integer results responsive; large integer results are displayed exactly.
GOOD TO KNOW
Common questions
What is the difference between combinations and permutations?
Combinations ignore order; permutations count each order separately.
Can I use dependent events in AND or OR?
No. Those controls assume independence. Use supplied conditional probabilities in a dedicated conditional-probability model.
Are results uploaded?
No. The calculation is local to your browser.