🌟 Understanding Flow Variables in ServiceNow Flow Designer

Abhishek_Thakur · 2 hours ago

Flow Designer has truly transformed how we build automation on the Now Platform. Its low-code, intuitive design allows developers and admins to build powerful workflows without writing heavy scripts.
Among the many capabilities Flow Designer offers, Flow Variables are one of the most important — yet often overlooked — features.

In this article, we’ll break down what Flow Variables are, why they matter, and how you can use them with a simple, real-world example.

🔹 What Are Flow Variables?

Flow Variables are temporary data holders that store information during the flow execution.
Think of them as small containers that help you:

Store values
Pass information between steps
Build conditions
Perform calculations
Reuse data multiple times in the same flow

They exist only during the run of a single flow and help eliminate unnecessary scripting or complex logic.

🔹 Why Are Flow Variables Important?

Flow Variables bring several benefits to Flow Designer:

✔️ 1. Cleaner Automation Logic

Instead of repeating lookups or running multiple actions, you can store the result once and use it anywhere in the flow.

✔️ 2. Improved Performance

By saving frequently used data in variables, your flow avoids unnecessary queries or API calls.

✔️ 3. Flexible & Dynamic Flows

Variables allow the flow to make decisions on the fly, such as counting records, validating values, or setting fields based on dynamic logic.

✔️ 4. Reduced Scripting

Many tasks that once required scripting can now be handled through variables and simple logic steps.

🔹 Types of Flow Variables

Flow Designer allows multiple variable data types, including:

String
Number
Boolean
Object
Array
Glide Date/Time
JSON

This allows you to store everything from simple text to structured data.

🔹 Real-Time Example: Storing Incident Count by Category

In my latest implementation (also shown in my YouTube video), I used a Flow Variable to calculate and store the total number of incidents with the same category as the one being created.

🔸 Use Case:

Whenever a new incident is created, calculate how many incidents already exist with the same category and store this number in a field on the new record.

🔸 Steps Involved:

Trigger – Flow runs when an Incident is created.
Create a Flow Variable – A Number variable named incidentCount.
Use a Script Step or Lookup Step – Query incident table and count records matching the selected category.
Store the Count in the Variable – Set the flow variable value dynamically.
Update the New Incident – Use the "Update Record" action to store the count back into the incident.

🔸 Outcome:

Every newly created Incident now displays how many similar category incidents exist — making reporting, analysis, and routing much smarter.

🔹 When Should You Use Flow Variables?

Flow Variables are ideal when:

You need to reuse a value multiple time
Your flow needs conditional logic
You want to pass data between steps
You’re performing iterative or calculated operations
You want to avoid hardcoding or repetitive lookups

They’re especially useful in flows that involve aggregations, API calls, calculations, or branching.

If you also want to watch the real-time demo on the above use case, then follow the below link:-

https://youtu.be/S2QfGxFUTPI?si=VRDTrcYVDjO2jUCC

If this article gives useful information, then please mark it as helpful.

Regards,

Abhishek Thakur