Probability Calculator
Compute probabilities from counts, combine independent events (AND/OR), and find complements.
Number of Successes
Total Trials
Calculate P (from counts)
P(A) (0 to 1 or %)
P(B) (0 to 1 or %)
Input Unit
Decimal (0–1)
Percent (0–100)
Calculate AND / OR
P(A) for Complement (0 to 1 or %)
Input Unit
Decimal (0–1)
Percent (0–100)
Calculate Complement
Clear All
P from Counts
—
AND (A ∩ B)
—
OR (A ∪ B)
—
Complement (A′)
—
Notes: For independent events,
P(A ∩ B) = P(A) × P(B)
and
P(A ∪ B) = P(A) + P(B) − P(A)P(B)
. Complement is
1 − P(A)
.