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Response rate vs completion rate

Response rate is the share of people invited to a survey who responded, usually completed responses divided by the eligible people invited. Completion rate is the share of people who started the survey and finished it. The first measures reach and willingness to take part; the second measures whether the survey itself lost people.

The two numbers fail for different reasons, so mixing them up sends the fix to the wrong place. A low response rate is a problem with the invitation and the audience, while a low completion rate is a problem with the form.

Nuwan Madhusanka · Co-founder

5 min read · Published 13 September 2026

The two rates side by side
Measure	Response rate	Completion rate
Question it answers	Did the invited people take part?	Did the people who started finish?
Usual formula	Responses divided by eligible people invited	Completed responses divided by people who started
What you must count	Invitations delivered	Starts, not only submissions
What drags it down	Wrong audience, weak invitation, poor timing, no reminder	Length, sensitive or hard questions, a layout that breaks on a phone
Who can fix it	Whoever owns the list and the invitation	Whoever wrote the questions and built the form
Standard reference	AAPOR Standard Definitions, response rates RR1 to RR6	No single standard; each survey tool defines it

Why the definitions disagree between tools

Before the early 1980s, response, cooperation and completion rates were often treated as interchangeable, and AAPOR's Standard Definitions exist to separate them. The tenth edition, published in 2023, sets out several response rate formulas that differ mainly in how partial interviews and cases of unknown eligibility are treated. Commercial tools are looser. SurveyMonkey's benchmark guide, for example, defines response rate as the people who started a survey divided by everyone who received it, which is closer to what a researcher would call a start rate. Neither is wrong, but a response rate of thirty percent under one definition and thirty percent under another can describe very different surveys. Completion rates vary too: some tools count only people who reached the final page, so a survey that ends early for screened out respondents looks worse than it is. Whenever the number appears in a report, put the formula and both counts beside it.

The funnel between the two

Picture a fictional physiotherapy clinic, Harbourline Physio, sending a follow up survey. It emails 1,200 patients and 1,150 messages are delivered. Of those, 310 people open the survey and begin, and 248 reach the end and submit. Counting completed responses against delivered invitations gives a response rate of 21.6 percent. The start rate, people who began against invitations delivered, is 27.0 percent. The completion rate, finishers against starters, is 80.0 percent. Laid out this way the story is clear: most of the loss happened before anybody saw a question, and the survey itself kept four in five of the people who opened it. A report that quoted only 80 percent would sound excellent and hide the fact that almost four in five patients never took part.

What each one tells you to change

A weak response rate points at the contact, not the questionnaire. The sender name, the subject line, the day and time, whether the invitation says how long the survey takes, and whether a reminder follows all matter far more than question wording. Dillman's Tailored Design Method is built around this stage, treating every contact as part of one planned sequence. A weak completion rate points inward. Look for the question where people stop: a demand for personal details on the first screen, a large grid, an open question nobody expected, or a page that does not fit a phone. Fixing the second problem with better email copy, or the first by cutting questions, is the usual waste of a survey cycle.

Neither number measures quality

It is tempting to treat a high rate as proof that the results are right. AAPOR's own guidance warns against this: studies comparing survey estimates with census benchmarks found that some of the least biased results came from surveys with less than optimal response rates, and it advises treating every response rate with scepticism. Pew Research Center reached a similar conclusion in 2017, when telephone polls with response rates of around nine percent still matched high response surveys on party affiliation but badly overstated volunteering. In that study 46 percent of telephone respondents said they had volunteered, against 8 percent in the government's Current Population Survey, a gap no response rate figure would have revealed. The rate tells you how much room there is for the missing people to differ. Whether they actually do is a separate question.

Counting both when the survey is a form

The responses table holds submissions only, and nothing saves a half filled form, so a finished response is the only thing a form can count on its own. The response rate numerator is simply the number of rows. The denominator comes from whatever sent the invitation, such as the mailing list tool that reports deliveries. A completion rate needs starts, which have to be measured outside the form, for example with analytics on the page that holds the link. The CSV export puts Submitted At in the first column, which makes it easy to see how many responses each reminder brought in. Test the form with the demo link first, because a demo submission records nothing and cannot inflate either count.

Questions people ask

Should partial responses count towards the response rate?

It depends on the formula you choose, and the choice should be stated. AAPOR's formulas include versions that count only completed interviews and versions that add partial interviews. If your tool keeps partials, decide in advance what counts as partial, such as answering the key questions, so the rule is not chosen after seeing which version looks better.

What is a cooperation rate?

A cooperation rate divides responses by the people who were actually reached, rather than everyone invited. It removes the people who never received or opened the invitation, so it isolates how persuasive the survey was once somebody saw it. AAPOR's Standard Definitions treat it as a separate measure from the response rate for exactly that reason.

Is a very high completion rate always good news?

Not always. A survey that forces an answer on every question can post a high completion rate while collecting careless answers from people who just wanted to reach the end. A screener that ends the survey early can also count as a completion. Look at straight lining and open answer quality before celebrating the number.

What is a drop off rate?

It is the mirror image of the completion rate: the share of people who started but did not finish. The useful version is drop off per question, which shows where people leave. A sharp step at one question is a design problem you can fix; a gentle slope across the whole survey usually means it is simply too long.

Do reminders change both rates?

Reminders mainly lift the response rate, because they reach people who never started. They rarely change completion, since the survey that loses people is the same survey. Two spaced reminders are common. If responses are anonymous, the reminder goes to everybody, so word it to thank people who have already answered.

Which rate belongs in a report?

Both, with their formulas and raw counts: invitations delivered, people who started if you know it, and completed responses, plus the dates the survey ran. A reader can then recalculate any rate they prefer. A single percentage with no denominator is the version that gets misquoted in the next meeting.

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Sources

Written and checked by the OneCraft team. Last checked 13 September 2026.