What is P(A and B) for independent events?
P(A and B) = P(A) × P(B). Example: P(heads)=0.5 and P(six)=1/6 gives 0.5 × 1/6 ≈ 0.0833.
P(not A) = 0.500000
P(A and B) = 0.125000
P(A or B) = 0.625000
Evaluate complements, joint, and union probabilities for independent events—calculated locally, never uploaded.
P(not A) = 0.500000
P(A and B) = 0.125000
P(A or B) = 0.625000
A probability calculator computes complements, joint probability P(A and B), and union P(A or B) for independent events from decimal or percent inputs.
Probability measures how likely an event is on a scale from 0 (impossible) to 1 (certain). For independent events A and B, the joint probability is P(A and B) = P(A) × P(B), and the union is P(A or B) = P(A) + P(B) − P(A)×P(B).
This tool also shows the complement P(not A) = 1 − P(A). It is for event probabilities—not for counting arrangements (use combination/permutation tools) or descriptive statistics (mean, standard deviation).
All math runs in your browser; values you enter are not uploaded to servers.
Independent events multiply for AND and use inclusion-exclusion for OR.
Concise answers for common searches — definitions, steps, and comparisons.
P(A and B) = P(A) × P(B). Example: P(heads)=0.5 and P(six)=1/6 gives 0.5 × 1/6 ≈ 0.0833.
No. Calculations run locally in your browser; values are not sent to servers.
Input the probability of event A as a decimal between 0 and 1 (e.g., 0.5 for 50%).
Add a second independent event probability when you need AND or OR results.
View P(not A), P(A and B), and P(A or B) updated instantly as you type.
These formulas assume A and B are independent—dependent events need conditional probability tools.
Input
P(A) = 0.5, P(B) = 0.25Output
P(A and B) = 0.125, P(A or B) = 0.625Joint = 0.5 × 0.25; union = 0.5 + 0.25 − 0.125.
Common real-world scenarios where this tool saves time.
Check complements and independent joint/union probabilities before submitting exercises.
Model simple independent risks (e.g., two system failures) without a spreadsheet.
Verify combined odds for independent loot drops or dice outcomes.
| Tool type | Output | Example question |
|---|---|---|
| This calculator | Probability 0–1 | P(heads and roll 6)? |
| Combination calculator | Count of ways | How many 3-card hands? |
| Permutation calculator | Ordered arrangements | How many PIN codes? |
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For independent events, P(A and B) = P(A) × P(B). Example: P(heads) × P(roll 6) = 0.5 × 1/6.
P(A or B) = P(A) + P(B) − P(A)×P(B) when events are independent. This avoids double-counting overlap.
P(not A) = 1 − P(A). If P(A) = 0.3, then P(not A) = 0.7.
This tool evaluates event probabilities (0–1). Use combination or permutation calculators for counting arrangements (nCr, nPr).
Enter decimals between 0 and 1 (divide percent by 100). 25% = 0.25.
No. All calculations run locally in your browser.
Probability values are processed in your browser—they are not uploaded to EverydayTools servers.
Formulas assume independent events; dependent events require conditional probability methods.
Educational estimates only—not actuarial, legal, or medical risk modeling.
More free tools for the same workflow.
Calculate permutations nPr = n!/(n−r)! when order matters—5P2, 10P3, 26P3 & more. Runs locally in your browser, no upload. Exact results up to n=500.
Calculate combinations nCr = n!/(r!(n−r)!) for unordered selections. No upload: runs locally in your browser. Free, instant nCr results.
Use a scientific calculator for trigonometry, logarithms, powers, roots, and constants with DEG/RAD support and instant browser-based results.
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Reviewed by EverydayTools Editorial Team on 2026-05-20.