Probability Fraction Calculator

Enter the number of favorable outcomes and total outcomes for up to 5 events to get the probability as a fraction. For each event, input your outcome count and total count — the calculator reduces the fraction to its simplest form and shows the combined probability when multiple events are involved. Also try the use the Uniform Distribution Calculator.

Must be greater than zero

Results

Combined Probability (Fraction)

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Event 1 Probability (Fraction)

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Event 2 Probability (Fraction)

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Event 3 Probability (Fraction)

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Event 4 Probability (Fraction)

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Event 5 Probability (Fraction)

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Combined Probability (Decimal)

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Combined Probability (%)

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Results Table

Frequently Asked Questions

What is the probability of an event?

The probability of an event is a measure of how likely that event is to occur relative to all possible outcomes. It is calculated as the ratio of favorable outcomes to total possible outcomes, and always falls between 0 (impossible) and 1 (certain). See also our Permutation Calculator.

Can probability be expressed as a fraction?

Yes — a fraction is one of the most natural ways to express probability. The numerator represents the number of favorable outcomes and the denominator represents the total number of possible outcomes. For example, rolling a 3 on a standard die has a probability of 1/6.

How do I find probability in fraction form?

Divide the number of favorable outcomes by the total number of possible outcomes, then simplify the fraction by dividing both numbers by their greatest common divisor (GCD). For instance, 4 favorable outcomes out of 8 total simplifies to 1/2.

What is the fraction form of the probability for a coin toss?

A fair coin has 2 possible outcomes (heads or tails). The probability of getting heads is 1/2, and the same applies to tails. This means each outcome has an equal 50% chance. You might also find our calculate Probability Distribution useful.

How do I calculate the probability of multiple events happening together?

For independent events, multiply their individual probabilities together. For example, if Event 1 has probability 1/2 and Event 2 has probability 1/3, the combined probability of both occurring is 1/2 × 1/3 = 1/6. This calculator handles up to 5 events simultaneously.

What does 'simplifying' a probability fraction mean?

Simplifying means reducing the fraction to its lowest terms by dividing both the numerator and denominator by their greatest common divisor. For example, 6/8 simplifies to 3/4. The value of the probability doesn't change — only its representation is made simpler.

Are the events assumed to be independent in this calculator?

Yes. This calculator assumes all events are independent of each other, meaning the outcome of one event does not affect the others. For dependent events (e.g. drawing cards without replacement), a different approach using conditional probability is required.

What is the difference between probability as a fraction, decimal, and percentage?

They are all equivalent representations of the same value. A fraction like 1/4 equals 0.25 as a decimal and 25% as a percentage. Fractions are often preferred in theoretical probability because they show the exact ratio without rounding errors.