You can use formula-type variables to dynamically calculate percentages inside your form. This is useful for grading quizzes, analyzing survey results, calculating metrics like ROI, or applying discounts to the final price.
💡 Learn more about formula variables, their use cases, and setup nuances in this article on how to use a variable with a formula
💡 Learn more about all variable types and general use cases in this article on what variables are, why & how to use them
When do you need percentage calculations?
You’ll often want to calculate percentages in use cases like:
Calculating metrics like ROI (e.g.,
result / investment × 100)Showing how much of a total score was achieved on a quiz
Estimating discounts or price reductions
Let’s go through three examples that show different ways to calculate percentages in forms.
How to set up the formula for your variable
To add a formula-type variable:
Go to the Variables tab in your form editor and add a new variable with type set to Formula.
In the Default Formula field, use math operations (+, −, *, /), numbers, or pull values from other fields or variables by referencing their IDs (e.g.
total_price * 0.75).
☝️ Parentheses are not supported in the formula variables. When setting up formulas, avoid using parentheses. For complex calculations, follow a step-by-step approach by creating separate variables for each part of the calculation.
Example 1: ROI calculator
Let’s say you want to calculate return on investment based on two values submitted in your form.
Step 1: Create number fields for input
Add two number fields with IDs:
returnandinvestment.
Step 2: Add a formula variable to calculate ROI
Add a formula variable with ID
roi, and addreturn / investment * 100in the Default formula field.
Step 3: Show the result using answer piping
Display the calculated ROI in a content block or on the ending page using answer piping:
Example 2: Personality quiz with percentage scores by trait
Let’s say your personality quiz gives a separate score for each trait, and you want to calculate what percentage of the total each trait represents — for example, “70% dominant and 30% conscientious.”
Step 1: Build a personality quiz with trait-based scoring
Create a quiz with four integer or decimal variables:
dominance,influence,steadiness, andconscientiousness. Use logic rules to add points to these variables based on respondents’ answers.
💡 If you haven't created a personality quiz yet, start with this guide on building a personality quiz with multiple outcomes (personality traits) and conditional scoring based on user's answers
Step 2: Add a variable for total score
Since formulas don’t support parentheses, you need to break calculations into separate steps, first calculating the total score as the sum of scores, like this:
Add a formula variable with ID
total_score, and use this formula:
dominance + influence + steadiness + conscientiousness
Step 3: Create percentage variables for each trait
To be able to calculate the % of each trait from the total:
Create four new formula-type variables – for example, for an integer variable for
dominance, create an additional formula variable with IDdominance_percent.In each formula, divide the trait's score by the total score and multiply by 100 to get a % value:
dominance_percent → dominance / total_score * 100
influence_percent → influence / total_score * 100
steadiness_percent → steadiness / total_score * 100
conscientiousness_percent → conscientiousness / total_score * 100
Step 4: Show the result using answer piping
Display the final results using content blocks or ending page messages with answer piping. For example:
You're @dominance_percent% dominant – bold, driven, and quick to take charge,
You're @influence_percent% influential – expressive, outgoing, and energised by people and ideas,
Etc.
Example 3: Total price with a discount
Let’s say you want to apply a discount to the final price in your form.
Step 1: Use a formula variable to apply the discount
In your form, where you already have a field or variable that holds the total price value (e.g.,
price_estimate), create an additional formula-type variable to apply the discount.Since subtracting percentages directly isn’t supported, you’ll want to multiply instead:
For a 10% discount, use price_estimate * 0.9
For a 25% discount, use price_estimate * 0.75
Step 2: Show the discounted price using answer piping
In a content block or on the ending page, use answer piping to display the discounted price to the respondent. For example: “Enjoy 10% off for your first order! Discounted price: $@discounted.”
You can now build smarter, dynamic forms that calculate percentages in real time — whether for scoring, pricing, or logic-based workflows.