A calculated value lets a Text Variable get its value automatically from another question's answer or another variable, instead of you typing it in or setting up conditions. It's helpful whenever you want to reuse part of an answer somewhere else in your survey, in exports, or in outbound emails, without asking the respondent twice.
Use case: You collect a respondent's Full Name in a single question, but you want a "Last Name" variable on its own, to personalize a follow-up email ("Hi Doe,") or to show up as its own column in your results. A calculated value does this for you: pick Full Name as the source, tell it to keep the last part, and every response fills it in automatically.
Setting up a calculated text variable
1. In your builder, go to Settings > Assignment & Formulas > Text Variables.
2. Click Create Variable (or click the edit icon on an existing variable to change it to a calculated value).
3. Enter a Variable name.
4. Under Value type, choose Calculated value.
5. Under Question or variable, choose the question or variable you want to base this on. Only text-answer questions (Short Text / Long Text) and other Text Variables show up here.
6. Under Change type, choose what to do with the answer. See "Ways you can change the answer" below for what each option does.
7. Fill in the extra fields that appear for the change type you picked (for example, Separator and Keep for splitting an answer).
8. Click Save Variable (or Update Variable if you're editing one).
That's it. This variable now fills in automatically for every response, based on that question's or variable's answer.
Example: Splitting a Full Name into a Last Name
1. Create a Short Text question asking for "Full Name".
2. Go to Settings > Assignment & Formulas > Text Variables and click Create Variable.
3. Name it "LastName", set Value type to Calculated value.
4. Set Question or variable to your Full Name question.
5. Set Change type to Take one part of the answer.
6. Leave Separator blank (defaults to a space) and set Keep to Last part.
7. Save. If a respondent answers "John Doe", LastName automatically becomes "Doe" - ready to use in recall text, results, exports, or a follow-up email.
Note: Only text-answer questions (Short Text, Long Text) and other Text Variables can be used as the source - question types like Multiple Choice or Rating aren't available here, since there's no free text to work with.
If you try to delete a question or variable that a calculated variable depends on, BlockSurvey will warn you first, since removing it would leave that calculated variable without a value.
A calculated variable's value updates automatically as soon as its source question is answered, there's nothing else you need to do. It also works the same way whether the survey is taken One question at a time, Classic, or Conversational view.