Calculate repeated event chances using flexible attempt settings. See exact, minimum, and range probabilities instantly. Export clean results, tables, and summaries for later review.
| Scenario | Success Probability | Attempts | Target | Range | Exactly Target | At Least One | Range Probability |
|---|---|---|---|---|---|---|---|
| Sample repeated test | 0.35 | 8 | 3 | 2 to 5 | 0.278586 | 0.968136 | 0.805556 |
| Marketing response trial | 0.20 | 12 | 2 | 1 to 4 | 0.283468 | 0.931281 | 0.794568 |
| Quality check pass rate | 0.60 | 5 | 4 | 3 to 5 | 0.259200 | 0.989760 | 0.682560 |
This calculator uses the binomial model. It fits repeated attempts where each attempt has only two possible outcomes. One outcome is success. The other is failure. The success probability stays the same for every attempt.
Exact successes: P(X = k) = nCk × pk × (1 - p)n-k
At least one success: P(X ≥ 1) = 1 - (1 - p)n
No success: P(X = 0) = (1 - p)n
Range of successes: P(a ≤ X ≤ b) = Σ[nCk × pk × (1 - p)n-k]
Expected successes: E(X) = n × p
Variance: Var(X) = n × p × (1 - p)
Standard deviation: SD = √[n × p × (1 - p)]
Enter the chance of success for one attempt. Choose decimal or percent format. Then enter the total number of attempts.
Set the target successes value. This gives the exact, at least, and at most calculations for that count.
Enter minimum and maximum successes to measure an inclusive range. This is useful for acceptable performance bands.
Choose how many decimal places you want. Press the calculate button to display the results section above the form.
Use the CSV button to save the result table. Use the PDF button to keep a printable summary for reports or class notes.
This calculator helps you measure what may happen across several attempts. It is useful when each attempt has the same success chance. That makes it a good fit for binomial probability. You can test exact results, broad ranges, and summary measures in one place. The layout keeps the workflow simple. You enter the inputs once, then review many outputs together.
Repeated-attempt probability appears in many fields. A student may test quiz answers, a marketer may estimate responses, and a quality team may track defects. A coach may review shot success. A lab may measure pass or fail outcomes. This page supports those common cases. It shows the chance of exactly k successes, at least k successes, at most k successes, and a chosen success range.
Exact values are important, but range values often matter more in real decisions. A manager may not care about exactly four successful events. The manager may care about getting between three and five. That is why this calculator includes a minimum and maximum success range. It also reports no success, at least one success, and all attempts succeeding. These outputs help you read risk more clearly.
The calculator also reports expected successes, variance, and standard deviation. These values add context to the probability table. The expected value shows the average long-run count. Variance shows how spread out the outcomes are. Standard deviation gives that spread in the same unit as the result count. These measures are useful when you compare different scenarios with different success chances or attempt totals.
After calculation, the results appear above the form for quick review. That saves scrolling during repeated testing. You can also export the output as CSV or PDF. This helps when you need to share results with a class, team, or client. The example table gives a fast reference point before you enter your own values. It makes the page practical for both learning and daily work.
It measures probabilities across repeated attempts when each attempt has the same success chance and only two outcomes, success or failure.
Use it when attempts are independent, the success chance stays constant, and every attempt ends in success or failure.
Exact means one specific success count. At least means that count or any higher count up to the total attempts.
Yes. Choose percent format, then enter values like 35 for 35%. Decimal format expects values like 0.35.
Expected value gives the average number of successes over many repeated runs. It helps compare scenarios quickly.
It means the chance that total successes fall between your minimum and maximum values, including both limits.
Yes. The page includes CSV and PDF export buttons after a successful calculation.
This happens when the minimum is greater than the maximum or when the selected values fall outside the possible success count range.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.