--- title: "Combination Calculator | Probability & Combinatorics Tool | XTRAW Tools" description: "Calculate nCr — the number of ways to choose r items from n without regard to order. Use this free browser-based probability calculator from XTRAW Tools for quick counting and chance estimates." url: "https://xtraw.com/tools/statistics-calculators/combinatorics-calculators/combination-calculator" date: "2026-06-24T21:38:47+00:00" language: "en-GB" --- [Permutation Calculator](https://xtraw.com/tools/calculators/statistics-calculators/combinatorics-calculators/permutation-calculator) [![Combination Calculator from XTRAW Tools](https://xtraw.com/images/virtuemart/product/xtraw-combination-calculator-360x360.jpg)](https://xtraw.com/images/virtuemart/product/xtraw-combination-calculator-360x360.jpg "Combination Calculator from XTRAW Tools") new [Back to: Combinatorics Calculators](https://xtraw.com/tools/calculators/statistics-calculators/combinatorics-calculators "Combinatorics Calculators") # Combination Calculator Calculate nCr — the number of ways to choose r items from n without regard to order. Use this free browser-based combination calculator from XTRAW Tools. **Combination Calculator** helps you calculate nCr — the number of ways to choose r items from n without regard to order. Use this free browser-based calculator from XTRAW Tools to compare inputs, estimate results, and plan your next step. ## How to Use the Combination Calculator 1. Enter the required calculator inputs shown in the form. 2. Review the probability, experiment, sample, velocity, acceleration, distance, force, angle, or physics assumptions. 3. Run the calculator, then adjust one input at a time to compare scenarios or check your estimate. ## What This Calculator Helps With Calculate nCr — the number of ways to choose r items from n without regard to order. It is designed for students, teachers, probability learners, analysts, game users, researchers, and anyone working with probability or counting problems who want a fast, browser-based estimate before relying on a spreadsheet, textbook, analytics platform, physics software, research software, professional source, or specialist. - n (total items): 10 - r (items chosen): 3 ## Common Uses People use this calculator when they need a quick way to estimate chance, count outcomes, compare probability assumptions, or check a combinatorics formula. - **Math Solving:** Solve probability, combinatorics, A/B testing, effect size, physics, motion, force, or work formulas from entered values. - **Random Selection:** Explore lottery, probability, and counting outcomes for education, planning, and chance demonstrations. - **Measurement:** Measure odds, combinations, conversion lift, effect size, velocity, acceleration, force, work, range, or related computed values. ## Formula or Method C(n,r) = n! / (r! × (n−r)!) ## Example **Example inputs:** n (total items): 10; r (items chosen): 3 **Example result:** Using the default inputs, C(10,3) = 120. ## Related Tools - [Permutation Calculator](https://xtraw.com/tools/permutation-calculator) - [Probability Calculator](https://xtraw.com/tools/probability-calculator) - [Dice Probability Calculator](https://xtraw.com/tools/dice-probability-calculator) - [Coin Flip Probability Calculator](https://xtraw.com/tools/coin-flip-probability-calculator) - [Card Probability Calculator](https://xtraw.com/tools/card-probability-calculator) ## Combination Calculator FAQ ### Is the Combination Calculator free? Yes. This calculator is free to use on XTRAW Tools. ### Do I need to create an account? No. XTRAW tools are designed for browser-based use without requiring an account. ### Are the results exact? Results may be estimates depending on the inputs, formula, rounding, selected method, probability model, physics assumption, or purpose of the calculator. Always verify important results before relying on them. **Disclaimer:** This calculator is provided for general informational, educational, and convenience purposes only. It is not legal, financial, medical, gambling, lottery, academic, research, statistical consulting, safety, or professional advice. Always verify important results with a qualified professional, instructor, statistician, researcher, lottery authority, authoritative source, or appropriate specialist before making decisions. **Related Tools** ![Tooltip]() [![Permutation Calculator from XTRAW Tools](https://xtraw.com/images/virtuemart/product/resized/xtraw-permutation-calculator-360x360_230x230.jpg) Permutation Calculator](https://xtraw.com/tools/calculators/statistics-calculators/combinatorics-calculators/permutation-calculator "Permutation Calculator") Calculate nPr — the number of ordered arrangements of r items from n. Use this free browser-based permutation calculator from XTRAW Tools. Custom prototype for related products [![Probability Calculator from XTRAW Tools](https://xtraw.com/images/virtuemart/product/resized/xtraw-probability-calculator-360x360_230x230.jpg) Probability Calculator](https://xtraw.com/tools/calculators/statistics-calculators/probability-calculators/probability-calculator "Probability Calculator") Calculate basic, complementary, union, and intersection probabilities. Use this free browser-based probability calculator from XTRAW Tools. Custom prototype for related products [![Dice Probability Calculator from XTRAW Tools](https://xtraw.com/images/virtuemart/product/resized/xtraw-dice-probability-calculator-360x360_230x230.jpg) Dice Probability Calculator](https://xtraw.com/tools/calculators/statistics-calculators/probability-calculators/dice-probability-calculator "Dice Probability Calculator") Calculate probability of outcomes when rolling multiple dice. Use this free browser-based dice probability calculator from XTRAW Tools. Custom prototype for related products [![Coin Flip Probability Calculator from XTRAW Tools](https://xtraw.com/images/virtuemart/product/resized/xtraw-coin-flip-probability-calculator-360x360_230x230.jpg) Coin Flip Probability Calculator](https://xtraw.com/tools/calculators/statistics-calculators/probability-calculators/coin-flip-probability-calculator "Coin Flip Probability Calculator") Calculate the probability of getting exactly k heads in n coin flips. Use this free browser-based coin flip probability calculator from XTRAW Tools. Custom prototype for related products [![Card Probability Calculator from XTRAW Tools](https://xtraw.com/images/virtuemart/product/resized/xtraw-card-probability-calculator-360x360_230x230.jpg) Card Probability Calculator](https://xtraw.com/tools/calculators/statistics-calculators/probability-calculators/card-probability-calculator "Card Probability Calculator") Calculate probabilities of drawing specific cards from a standard 52-card deck. Use this free browser-based card probability calculator from XTRAW Tools. 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