Probability Calculator
Calculate probabilities for two events, series of independent events, and normal distributions
Two Events
Series of Events
Normal Distribution
Probability of Two Events
P(A ∪ B) = P(A) + P(B) – P(A ∩ B)
P(A ∩ B) = P(A) × P(B) [for independent events]
P(A ∩ B) = P(A) × P(B) [for independent events]
Calculate the probability of two events occurring, including union, intersection, and conditional probabilities.
Probability Results
P(A):
0.5000
P(B):
0.5000
P(A ∩ B):
0.2500
P(A ∪ B):
0.7500
P(A | B):
0.5000
P(B | A):
0.5000
P(neither):
0.2500
Venn Diagram
Series of Independent Events
P(all events) = P(E₁) × P(E₂) × … × P(Eₙ)
P(at least one) = 1 – P(none)
P(at least one) = 1 – P(none)
Calculate the probability of multiple independent events occurring in sequence.
Probability Results
All events occur:
0.1250
None occur:
0.1250
At least one occurs:
0.8750
Exactly one occurs:
0.3750
Probability Distribution
Normal Distribution
Z = (X – μ) / σ
Calculate probabilities and confidence intervals for a normal distribution. Enter the mean, standard deviation, and value to find the probability.
Normal Distribution Results
Z-Score:
0.00
Probability:
0.5000
Percentile:
50.00%
Confidence Interval (95%):
-1.96 to 1.96
Normal Distribution Curve
How to Use This Calculator
- Two Events Calculator: Enter probabilities for two events to calculate union, intersection, and conditional probabilities.
- Series of Events: Calculate probabilities for multiple independent events occurring together or separately.
- Normal Distribution: Enter mean, standard deviation, and value to find probabilities and Z-scores for normal distributions.
- All calculations are performed in your browser – no data is sent to servers.
- Results are displayed instantly with visual representations.