Patient Numbers

Patient Numbers Calculator

Estimate how many patients need to be screened to achieve a randomised target and how many are expected to complete the study.

Calculator

Enter study assumptions

Randomised patients Enter the target number of patients to be randomised into the study. Screen failure rate % Enter the expected percentage of screened patients who will not be randomised. Dropout rate % Enter the expected percentage of randomised patients who will not complete the study.

Methodology

How patient numbers are calculated

Patients required to screen

Randomised patients ÷ (1 − screen failure rate)

The result is rounded up because a fraction of a patient cannot be screened.

Expected patients completing study

Randomised patients × (1 − dropout rate)

The result is rounded to the nearest whole patient.

Scope

A simple planning estimate

Screen failure is applied before randomisation. Dropout is applied to randomised patients, not to the total number screened.

Planning tool only. Actual screening and completion numbers will vary. Use study-specific assumptions and review against the protocol and statistical/operational plan.