Probability Calculator

Probability always falls between 0 (impossible) and 1 (certain).

What this calculator does

P = favorable outcomes / total outcomes.

When to use this calculator

Reach for this calculator when you need a result you can act on confidently. The formula is straightforward, but manual computation introduces rounding errors that this tool eliminates entirely.

Common mistakes

The most frequent error is rounding intermediate values before completing the full calculation. Round only the final result — rounding intermediate steps compounds errors in multi-step calculations, sometimes significantly.

Real-world scenarios

A business owner spots that revenue grew from £180,000 last year to £213,400 this year. The calculator confirms the increase is 18.6% — a figure needed for the annual report and for comparing against the industry growth rate cited in the sector report.

Frequently asked questions

How do I calculate probability?

P = number of favorable outcomes / total number of possible outcomes.

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