Compare calculators

Both calculators run independently — change the inputs on either side to compare results.

Confidence Interval Calculator

Computes the range of values likely to contain a true population mean at your chosen confidence level. Use it when reporting survey results, clinical trial outcomes, or any estimate derived from a sample.

Sample Mean

Sample Standard Deviation

Sample Size (n) (observations)

Confidence Level

Distribution Type

Fill in the required fields to see your result.

Probability

Poisson Probability Calculator

Computes the probability of observing exactly k events in a fixed interval when events occur at a known average rate. Use it for call-centre arrivals, equipment failures, or any count of rare, independent events.

Average Rate (λ) (events)

Number of Events (k)

Time Interval

Fill in the required fields to see your result.

Key differences

	Confidence Interval Calculator	Poisson Probability Calculator
Category	Probability	Probability
Inputs required	5	3
Result	Margin of Error (±)	Probability
What it does	Computes the range of values likely to contain a true population mean at your chosen confidence level. Use it when reporting survey results, clinical trial outcomes, or any estimate derived from a sample.	Computes the probability of observing exactly k events in a fixed interval when events occur at a known average rate. Use it for call-centre arrivals, equipment failures, or any count of rare, independent events.