Recruitment

Recruitment Calculator

A simple recruitment estimate using one recruitment rate and a gradual site activation schedule. For high/medium/low rates and a cumulative recruitment graph, choose Advanced forecast.

Calculator

Enter recruitment assumptions

What do you want to calculate? Choose what to calculate, then enter the other values and the number of sites activated each month.

Randomised patient target Enter the number of patients you plan to randomise. Number of sites Enter the number of recruiting sites. Patients/Site/Month Enter expected randomised patients recruited per site per month. Recruitment duration (months) Enter the target number of calendar months from First Patient In (FPI) to LPI.

Sites activated per month Enter how many new sites you expect to activate per month, starting in Month 1 (FPI reference).

Methodology

How the ramp-up is calculated

1. Site activation

Enter how many sites you expect to start each month. The calculator adds these sites gradually until all planned sites have started.

2. Recruiting site-months

Sites already active recruit for the full month. Newly activated sites are assumed to recruit for half their first month.

3. Patient recruitment

Expected randomised patients = cumulative recruiting site-months × Patients/Site/Month.

4. Reverse calculations

For a fixed deadline, the model searches for the minimum whole site count, or calculates the required Patients/Site/Month. For duration, it finds the first whole month in which the target is reached.

Scope

An indicative FPI-based recruitment estimate

Month 1 is referenced to FPI; site activation is modelled from that month and continues at the entered rate until all planned sites are active. Newly activated sites are assumed to recruit for half of their first month, then for full months thereafter. This is a simplified planning estimate: it does not model pre-FPI site activation, start-up delays, non-recruiting sites, country differences, seasonality, recruitment pauses, screening activity, screen failure, site caps or uncertainty ranges. Rates are for randomised patients; do not deduct screen failure again.

Planning tool only. The result is a mathematical expected-value estimate, not a guaranteed operational milestone. Recruitment performance varies by indication, geography, site and study design.