Survey Response Rate Calculator

This calculator works backward from a target number of completed surveys to the number of invitations you need to send, using two rates: Expected Response Rate (the share of invitees who start the survey) and Completion Rate (the share of starters who finish it). Effective Response Rate is the product of the two (line 13), and Invitations to Send is the target divided by that effective rate, rounded up (line 14, Math.ceil). Because Effective Response Rate is a plain product, a proportional change to Expected Response Rate and a proportional change to Completion Rate move Invitations to Send by essentially the same amount — a 10% bump in either one cuts the invitations needed by about the same fraction. Both rates fall back to their field defaults before any floor applies: the code is Math.max(0.1, inputs.expectedResponseRate || 20) / 100 (lines 9-10), and the || operator runs first, so typing a literal 0 — or clearing the field — is replaced by that field's default (20 for Expected Response Rate, 80 for Completion Rate), not floored to 0.1%.

The 0.1% floor only ever catches a value you type strictly between 0 and 0.1, such as 0.05. Expected Survey Starts is the number of invitees projected to begin the survey, and Expected Drop-offs is however many of those starters are projected not to finish, clamped at 0 so it never reads negative even with unusual inputs. This calculator does not account for invitation delivery failures — bounces, spam filtering, or duplicate contacts — or for response rates declining as invitation volume grows; it assumes Expected Response Rate and Completion Rate hold constant no matter how many invitations you actually send.