Working with Formulas in Calculator widget
At the heart of the Calculator widget are formulas, which allow you to perform complex mathematical operations on user data.
In this guide, we'll cover the basics of making formulas. If you've used Excel or similar spreadsheet programs before, you'll find it especially easy to follow along.
In case you need a refresher on the basics of the Calculator widget, please head over to this article  Getting Started with the Calculator.
In this article
Working with Formula Editor
To begin crafting your first formula, add a new Calculation on the Build tab → Add Calculation:
Then start writing your formula in the Formula editor:
 1

Fields act as variables that dynamically fetch values from their corresponding fields. They are selected from the dropdown. When added, they are depicted in purple:
For a more indepth overview of working with Fields, refer to this section of the article  Using Fields in Formulas.
Remember, you must select a Field from the dropdown menu. Even if you enter the field name correctly using your keyboard, the formula won't validate.  2

Calculations also function as variables, retrieving values from their respective calculations. They are represented in green:
You can find a more detailed guide on using calculations in this article section  Simplifying Formulas with Calculations.
Keep in mind that you must select a Calculation from the dropdown menu. Even if you enter the field name correctly using your keyboard, the formula won't validate.  3

Functions are tools used to perform specific operations or calculations on data. They can be selected from the dropdown menu. The names of functions and syntax elements, like round brackets and commas, are displayed in white:
The article section titled Calculator Functions provides detailed guidance on how to use the functions available.
 4

Some Mathematical operators such as addition, subtraction, multiplication, division, and exponentiation, along with round brackets, are available as buttons in the bottom row. They appear in white:
The editor follows the standard mathematical order of operations: Parentheses, Exponents, Multiplication and Division, and Addition and Subtraction.
For example, this formula will yield a result of 7:
However, adding round brackets to the formula, like this, will change the result to 9:
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Additionally, you can input numbers directly from your keyboard, which are highlighted in brown:
Numeric values can also be expressed as decimals (e.g., 0.01), or as percentages (e.g, 1%).
You'll notice that writing formulas in the widget is similar to Excel, but instead of cell data, you work with Fields and Calculations.
To assist you in writing accurate formulas, the widget also includes a builtin validator. Simply click outside of the Formula editor to activate it. If there's an issue with your formula, it will display an Invalid Formula error message.
The validator catches the following errors:
 Syntax mistakes in the formula:
 Use of a deleted Field or a deleted nested Calculation:
 Use of an invalid nested Calculation:
 Use of an unrecognized Field / Calculation variable entered from keyboard:
Be sure to carefully review your formula to correct any errors.
For guidance on styling the Calculation element of the widget, check out this article section  Adding Calculations.
Now, let's take a closer look at the Field component.
Using Fields in Formulas
When you choose a Field, you're selecting a variable that dynamically fetches the value of the user's response from that particular field:
A Field can be used as a variable both in mathematical operations and functions. Here's a simple example demonstrating the use of Field variables, first as an addend and then as arguments of a function:
Using Fields can get a bit tricky with Choice and Image Choice fields when Multiple Selection is enabled:
In the next section, we'll delve deeper into these nuances.
Peculiarities of Choice Fields with Multiple Selection
With Multiple Selection, users are presented with checkboxes, allowing them to select multiple options. Because of this, a Choice field might store an array of numbers instead of just a single number. Let’s imagine you have a Choice field with three checkboxes:
 Option 1 with a value of 1
 Option 2 with a value of 2
 Option 3 with a value of 3
When nothing is selected, the result shows 0: If a user selects just one option, let's say Option 1, it's straightforward  the Calculator simply uses the assigned value of that option (in this case, 1): However, when multiple options are selected in a Choice field, the Calculator cannot determine which value to use, resulting in a calculation failure: To avoid this issue, a Choice field with Multiple Selection is used within the SUM or CONTAINS function.
To better understand how to use these functions, let’s look at a practical example. We'll design a shipping cost calculator where the Product Type is a Choice field with Multiple Selection. The product type values are:
 Standard: $0
 Fragile: $10
 Perishable: $5
 Hazardous: $15
The base shipping cost is $2 per kg, calculated simply as Weight * 2
. Additionally, a surcharge fee is determined by the type of product being shipped.
Here's what the widget will look like:
Let's look at three ways to calculate the additional fee, highlighting special cases where you can use SUM or CONTAINS with Multiple Selection:
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Using CONTAINS to check if a certain option has been selected
Within the CONTAINS function, the first argument should be the Choice field, and the second argument is the value you're testing. Remember, CONTAINS can only be used within an IF function. Don't forget to specify what values to display when the IF function returns True and False. The template of the formula is
IF(CONTAINS(Choice, value to test), value if true, value if false)
.For example, we want to increase the shipping cost by 25% if the shipment includes hazardous products. We can use the formula
(Weight * 2) * IF(CONTAINS(Product Type, 15), 1.25, 1)
. This formula multiplies the base shipping cost by 1.25 if hazardous products are included; otherwise, it leaves the base cost unchanged:You might think that using
(Weight * 2) * IF(Product Type == 15, 1.25, 1)
would be the right formula for this scenario.However, the logical check in the format
IF(Product Type == 15, 1.25, 1)
only works if Multiple Selection is disabled. In our example Multiple Selection is enabled, so the CONTAINS function needs to be used instead.  2

Using SUM to calculate the sum of all selected options
To get the sum of all checked options, input the desired field as the argument of the SUM function:
SUM(Choice)
.In our example, we'll now add a flat fee to the total cost based on the values of the selected fields. We can achieve this using the formula
(Weight * 2) + SUM(Product Type)
:  3

Using SUM to test whether any option has been checked
To check if the user has selected at least one option, we can place the SUM function as the first argument of the IF function:
IF(SUM(Choice) > 0, value if true, value if false)
. If the user doesn't pick anything,SUM(Choice)
returns 0 by default. So, we compare this sum with 0. If the sum is greater than 0, it means at least one option has been checked.Let's rename the Choice field from Product Type to Special Product Type and remove Standard from the options since Standard products don't have any fees. We'll add a flat fee of $10 if at least one Special Product Type is selected. If none are selected, the IF function returns 0, and no fee is added.
The formula for this would be
(Weight * 2) + IF (SUM(Special Product Type) > 0, 10, 0)
:
Simplifying Formulas with Calculations
If your formula is becoming large and complex, simplify it by breaking it down into smaller parts! To do this, create a separate Calculation: Then, use this Calculation as a variable in another formula to streamline and clarify your overall calculation process. Let's go through a practical example. We'll create a basic deposit calculator. The user enters the deposit amount and the term. The calculator will show two results:
 the total amount to be received at the end (including the initial deposit and interest earned)
 the gained interest
Here’s what the widget will look like: To simplify the formula, we divided it into two calculations. In the first one, we calculate the total amount to be received at the end of the term Total Amount Receivable
, and in the second one, we calculate the gained interest Interest Receivable
. To calculate Total Amount Receivable
, create the first Calculation. In our example, we'll use the future value formula for simple interest, like this: The future value formula for simple interest is FV = PV * (1 + r * t), where:
 FV is the future value of the investment
 PV is the present value or principal amount
 r is the annual interest rate (expressed as a decimal)
 t is the time the money is invested for in years
In our example, this formula is written as Principal Amount * (1 + (2% * Term in years))
, where Principal Amount
and Term in years
are Slider fields. Next, create another Calculation for Interest Receivable
. To calculate the interest, subtract Principal Amount
from another Calculation  Total Amount Receivable
: All done! The advantages of simplifying formulas may not be immediately noticeable in a short formula like in this example. However, the formula Interest Receivable
is already easier to use, read, and edit.
Calculator Functions
Now that you've grasped the basics of working with formula building blocks, let's delve into one of the most powerful tools in our widget's arsenal  functions. Our Calculator supports 14 powerful Functions that you may know from doing basic calculations in spreadsheets:
Be sure to read the article all the way to the end to learn more about them, or simply follow the links above to skip ahead to the function references.
Using Mathematical Functions
First, we'll go over 9 mathematical functions that allow you do all sorts of standard calculations:
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MAX  returns the largest value in a set of values. Commas are used to separate multiple values:
Syntax Input Output MAX(value1, [value2], ...) MAX(3, 4, 1) 4  2

MIN  returns the smallest value in a set of values. Use commas to separate multiple values:
Syntax Input Output MIN(value1, [value2], ...) MIN(3, 4, 1) 1  3

ROUND  returns a number rounded to a given number of decimal places. The function rounds the number up if the last significant digit is 5 or greater and rounds it down if the last significant digit is less than 5:
Syntax Input Output ROUND(value) ROUND(123.32342) 123 ROUND(value, [places]) ROUND(123.32342, 2) 123.32 If you don't specify the number of places, the function rounds to the nearest whole number.  4

ROUNDUP  returns a number rounded up to a given number of decimal places:
Syntax Input Output ROUNDUP(value, [places]) ROUNDUP(123.32342) 124 If you don't specify the number of places, the function rounds up to the nearest whole number.  5

ROUNDDOWN  returns a number rounded down to a given number of places:
Syntax Input Output ROUNDDOWN(value, [places]) ROUNDDOWN(123.32342) 123 If the number of places isn't specified, the function rounds down to the nearest whole number.  6

ABS  returns the absolute value of a number. It means that negative numbers will be converted to positive numbers, and positive numbers will remain the same:
Syntax Input Output ABS(value) ABS(123) 123  7

RAND  returns a random number between 0 and 1:
Syntax Input Output RAND() RAND() Random value between 0 and 1, for example 0.3 Note that this function doesn't take any arguments.  8

RANDBETWEEN returns a random integer between two given numbers:
Syntax Input Output RANDBETWEEN(min value, max value) RANDBETWEEN(2, 5) Random value between 2 and 5, for example 4  9

SUM  returns the sum of values supplied. Enter your values manually or select a Choice field as an argument. Don't forget to separate multiple values by commas:
Syntax Input Output SUM(value1, [value2], [value3], ...) SUM(1,1,1) 3 As you may recall from the previous section, SUM is particularly handy when it takes a Choice or an Image Choice field as an argument. You can find more information on this topic by following this link  Peculiarities of Choice Fields with Multiple Selection.
Writing Conditions
Logical functions allow you to test whether a condition is true or false. Depending on the result of the test, you can choose what action to perform next.
The Calculator widget supports 5 logical functions:
 1

IF  runs a logical test on supplied values or expressions and returns the value after the first comma if the result is True, and the value after the second comma if the result is False:
Syntax Input Output IF(logical test, value if true, value if false) IF(true, 200, 0) 200 Keep in mind that other logical functions AND, OR, NOT and CONTAINS, as well as comparison operators (>, <, ==) can only be used within the IF function. When other logical functions are nested within IF, they allow you to test more than one condition at a time.
Note that the equality operator in the Calculator widget is double equals ==, and not a single equal = as in Excel. Let's take a look at how you can expand the capabilities of the IF function.
 2

AND  returns True only if both results are True, and returns False otherwise:
Syntax Input Output IF(AND(logical test 1, logical test 2), value if true, value if false) IF(AND(2==2, 1==1), 0, 1) 0 Unlike Excel, AND function in the Calculator widget accepts only 2 arguments.  3

OR  returns True if any given argument is True, and returns False if both arguments are False:
Syntax Input Output IF(OR(logical test 1, logical test 2), value if true, value if false) IF(OR(2==3, 1==1), 0, 1) 0 Unlike Excel, OR function in the Calculator widget accepts only 2 arguments.  4

NOT  returns the opposite of the result of the comparison. When given True, NOT returns False. When given False, NOT returns True:
Syntax Input Output IF(NOT(logical test), value if true, value if false) IF(NOT(2==3), 0, 1) 0  5

CONTAINS  returns True if the set of provided values contains the value specified after the comma, and returns False otherwise:
Syntax Input Output IF(CONTAINS(set of values, value to test), value if true, value if false) IF(CONTAINS([1, 2, 3], 50), 0, 1) 1 This is a unique Calculator widget function not present in Excel. Use a Choice field as the argument of CONTAINS to check if a particular option has been selected.
Now you know how to use functions and fields in formulas to build your first Calculator!
If you have any new features in mind or somethings doesn't work as expected, do make a post in our Wishlist! We'll consider every idea and do our best to implement it 🙌
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