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Volunteer Requirement Calculator

Work out volunteer requirement instantly with clear inputs, formula shown and shareable results.

About Volunteer Requirement Calculator

Shifts per role round the coverage hours up to whole shifts, the total shifts multiply that by the roles, and a reserve percentage is added for no-shows. Volunteer no-show rates of 15 to 25 percent are normal, so recruiting exactly to the shift count reliably leaves gaps on the day.

Formula

Volunteers needed

volunteers = ceiling(roles x ceiling(hours per role / shift length) x (1 + reserve))

Worked example

With the default values below, Volunteer Requirement Calculator returns Volunteers to recruit of 20. Change any input above and every figure here is recalculated in your browser.

Inputs used

Roles to coverminimum 1
8
Hours each role must be coveredminimum 0.1 h
6 h
Length of one volunteer shiftminimum 0.1 h
3 h
Reserve allowance for no-showsaccepts 0–100 %
20 %

Results

Volunteers to recruit
20
Shifts to fill
16
Total volunteer hours needed
48.0 h
Extra volunteers held in reserve
4

Step by step

  1. 1Values used
  2. 2Volunteers needed
  3. 3Volunteers to recruit= 20
  4. 4Shifts to fill= 16
  5. 5Total volunteer hours needed= 48.0 h
  6. 6Extra volunteers held in reserve= 4

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 1 decimal place, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is the Volunteer Requirement figure worked out?

volunteers = ceiling(roles x ceiling(hours per role / shift length) x (1 + reserve)). Shifts per role round the coverage hours up to whole shifts, the total shifts multiply that by the roles, and a reserve percentage is added for no-shows.

Why does this matter?

Volunteer no-show rates of 15 to 25 percent are normal, so recruiting exactly to the shift count reliably leaves gaps on the day.

What do I need to enter?

Enter roles to cover, hours each role must be covered, length of one volunteer shift, reserve allowance for no-shows. The defaults shown are a realistic worked example — swap in your own figures to get a result you can use.

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