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Response Rate Adjustment Calculator

Work out response rate adjustment instantly with clear inputs, formula shown and shareable results.

About Response Rate Adjustment Calculator

Response rate is completions over invitations, and inverting it sizes the invitation list. 620 responses from 5000 invitations is 12.4%, so reaching 1000 responses needs 8065 invitations - 3065 more than already sent. Response rates fall as a survey is re-sent, so the estimate is usually optimistic for later waves.

Formulas

Response rate

rate = completed responses / invitations sent

Invitations needed

needed = target responses / response rate

Worked example

With the default values below, Response Rate Adjustment Calculator returns Invitations Needed For The Target of 8,065. Change any input above and every figure here is recalculated in your browser.

Inputs used

Invitations sentminimum 1
5,000
Completed responsesminimum 0
620
Responses neededminimum 1
1,000

Results

Invitations Needed For The Target
8,065
Observed Response Rate
12.40%
Additional Invitations To Send
3,065
Responses Still Needed
380

Step by step

  1. 1Values used
  2. 2Response rate
  3. 3Invitations needed
  4. 4Invitations Needed For The Target= 8,065
  5. 5Observed Response Rate= 12.40
  6. 6Additional Invitations To Send= 3,065
  7. 7Responses Still Needed= 380

Assumptions and limits

  • The result is derived only from the 3 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 2 decimal places, 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

What response rate should I expect?

Around 10-25% for cold email surveys, 25-50% for existing customers and over 60% for internal employee surveys with management backing.

Why does the estimate understate what is needed?

Because the easiest respondents answer first. Marginal response rates on later reminders are typically half the initial rate.

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