Binomial Probability Calculator
Solve P(X = k) = ⁿCₖ pᵏ (1−p)ⁿ⁻ᵏ step by step — free binomial probability calculator with worked examples, real-world defaults and instant answers.
Binomial probability — P(X = k), at-most and at-least, with the three ingredients.
About Binomial Probability Calculator
The Binomial Probability Calculator solves P(X = k) = ⁿCₖ pᵏ (1−p)ⁿ⁻ᵏ for you with the full working shown — every substitution, every unit, every step, exactly the way a good teacher writes it on the board. Binomial needs all three assumptions: a FIXED number of trials, only two outcomes per trial, and the SAME independent p each time.
How to use Binomial Probability Calculator
- 1Enter your known values in the input fields (sensible real-world defaults are pre-filled).
- 2The tool substitutes them into P(X = k) = ⁿCₖ pᵏ (1−p)ⁿ⁻ᵏ and recomputes live.
- 3Read the answer in the result box, then expand the step-by-step solution to see the full working.
- 4Copy the method into your notebook, or change inputs to explore how the result behaves.
Why use Binomial Probability Calculator?
- ✓Solves P(X = k) = ⁿCₖ pᵏ (1−p)ⁿ⁻ᵏ instantly as you type — no submit button, no waiting
- ✓Step-by-step solution shown for every calculation, not just the final answer
- ✓Realistic example values pre-loaded so you can see a worked example immediately
- ✓100% free, no sign-up, runs entirely in your browser — your numbers never leave your device
- ✓Mobile-friendly and fast enough to use mid-homework or mid-lesson
Frequently asked questions
What formula does the Binomial Probability Calculator use?+
It uses P(X = k) = ⁿCₖ pᵏ (1−p)ⁿ⁻ᵏ. The steps section shows the formula with your actual numbers substituted, so you can follow (and verify) every stage of the calculation rather than trusting a black box.
What should I keep in mind when using this calculator?+
Binomial needs all three assumptions: a FIXED number of trials, only two outcomes per trial, and the SAME independent p each time. Coin flips and quality sampling qualify; drawing cards without replacement does not (that's hypergeometric).
Is the Binomial Probability Calculator free to use?+
Completely free, with no sign-up or limits. All computation happens client-side in your browser, so it is fast, private, and works even on slow connections once the page has loaded.
Can I use this for homework, teaching or exam prep?+
That is exactly what it is built for. The step-by-step working mirrors how solutions are presented in class, so you can check homework, build worked examples for teaching, or practise method recall before exams.
Embed Binomial Probability Calculator on your website
Want Binomial Probability Calculatoron your own site? Paste this snippet into any HTML page — it's free, with no API key or sign-up. The tool loads in an iframe and keeps working exactly as it does here.
<iframe src="https://tooljolt.com/tools/binomial-probability-calculator" width="100%" height="640" style="border:1px solid #e5e7eb;border-radius:12px;max-width:680px" title="Binomial Probability Calculator — ToolJolt" loading="lazy"></iframe>Related Science tools
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