How many volunteers do you actually need to recruit?

How the calculation works

Every step is arithmetic you can do yourself. The method is written out here deliberately, so the framework is readable, checkable, and quotable without running the tool.

1. Volunteer-slots needed = shifts to fill × volunteers per shift.
2. Adjust for no-shows: divide by (1 − no-show rate). If 15% don't arrive, you must schedule more people than slots.
3. Convert slots to people: divide by the shifts each volunteer covers, accounting for the fact that volunteers who drop off after one shift cover only one.
4. Adjust for first-shift drop-off: a volunteer who never returns contributes one shift, not their average, so the effective shifts-per-recruit falls.
5. Work back to applicants: divide by your application-to-first-shift rate.

What the result tells you

If the applicant number is far larger than the volunteer number, your losses are in conversion, not reach, more recruitment effort will mostly produce more leakage. Fixing response time or the application form will do more than another channel.

If the two numbers are close and you still cannot fill shifts, the problem genuinely is reach, and the channels section is the right place to start.

The default percentages are illustrative starting points, not benchmarks. No credible published figure exists for typical volunteer no-show or first-shift drop-off rates, and any specific number you see quoted for them usually traces back to a blog rather than a study. Replace them with your own figures as soon as you have two months of your own data. The tool is only as good as the numbers you put in.