Probability Calculator

Calculate combinations (nCr) and permutations (nPr) for any set size. Choose r items from n with or without order.

About Probability Calculator

This free probability calculator computes combinations (nCr) and permutations (nPr) for any set of items. Combinations count the number of ways to choose r items from n items where order does not matter. Permutations count the number of ways where order does matter. Use the tabs above to switch between modes.

Combinations (nCr)

Find how many ways to choose r items from n items when order doesn't matter, like selecting lottery numbers or committee members.

Permutations (nPr)

Find how many ways to arrange r items from n items when order matters, like ranking contestants or creating passwords.

Step-by-Step Work

See the formula with values plugged in and the full factorial expansion to understand how the result is derived.

Real-World Meaning

Get a plain-English explanation of what the result means in context, making abstract combinatorics concrete.

📋 Common Use Cases

Statistics & Data Analysis

Compute mean, median, standard deviation, and probability distributions for datasets. Analyze survey results, grades, or experimental data without specialized software.

Algebra & Calculus Support

Solve quadratic equations, find slopes and line equations, or compute prime factorizations. Check homework answers and understand the solution process.

Random Sampling & Simulation

Generate cryptographically secure random numbers for simulations, A/B testing, lottery drawings, or randomized experimental designs.

STEM Education & Tutoring

Teachers and students use these calculators to verify manual calculations, explore mathematical concepts interactively, and build intuition through experimentation.

🪜 How to Use This Tool

  1. Enter your values or equation
    Input numbers, data sets, or equation coefficients into the clearly labeled fields.
  2. Configure precision or method
    Set decimal places, choose solution methods, or select statistical measures — depending on the specific calculator.
  3. Review computed results
    See the primary answer plus supplementary information — step-by-step solutions, graphs, statistical summaries, or sequence terms.
  4. Verify or apply results
    Use the output to check manual work, complete assignments, or inform decisions. All computation happens locally for instant results.

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Frequently Asked Questions

Are these calculators really free?▼
Yes. All calculators on iluv.tools are completely free. No signup, no account, no credit card required. Every calculation runs instantly in your browser.
Is my data sent anywhere?▼
Absolutely not. All calculators are pure client-side JavaScript. Your numbers, dates, and inputs never leave your browser. No server processing, no tracking.
How accurate are these calculators?▼
Calculators use standard mathematical formulas with double-precision floating point. Results match industry-standard financial and scientific calculations.
Can I use calculators on mobile?▼
Yes. All calculators work on mobile browsers (iOS Safari, Android Chrome) with responsive layouts.