Everything you need to know about subforms

Most form fields collect a single answer: a name, a date, a selection. But real-world data is often more layered than that. When a customer places an order, they are not buying just one product. When an event planner books a venue, they might be scheduling multiple sessions. When HR runs an appraisal, they need to capture performance across several competencies.

What is a subform?

A subform is a secondary form embedded inside your primary form, letting respondents add as many structured line items as they need, each with its own set of fields. The outer form captures the overall record (for example, the "order"), while the subform captures the repeatable rows (the "order items").
Without subforms, you would need to create duplicate fields (Product 1, Product 2, Product 3…) and guess how many a respondent might need. Subforms eliminate that guesswork entirely. Respondents simply add as many entries as required.

Once collected, subform data integrates beautifully with the rest of Zoho Forms: it can appear in Thank You pages, email notifications (rendered as a table), and Formula fields for calculations and payment processing.

Types of subforms

Zoho Forms offers three display styles for Subforms. The data collected is the same, but the presentation and user experience differ meaningfully. Picking the right type depends on how many fields your Subform has and how you want respondents to interact with it.

Inline subform

In an Inline subform, all fields sit side by side in a horizontal row. Each new entry adds a fresh row directly inside the form. This is closest to the "spreadsheet" experience and works best when you have a small number of fields (3–5) that a respondent needs to scan at a glance.

Popup subform

When your subform grows beyond a few fields, squeezing everything into a horizontal row creates visual chaos. The Popup subform solves this elegantly. Respondents click + Add Entry, a full-screen popup opens for that entry, they fill it in, and the form shows a tidy summary row once it is saved.

The Add Entry label can be renamed to "Add Product", "Add Guest", "Add Session", whatever matches your form's context to improve respondent comprehension.

Vertical subform 

This is the newest addition to the Subform family. Instead of horizontal rows or popups, a vertical subform renders each entry as its own stacked block with fields listed top to bottom, just like the rest of the form. Each entry is visually distinct, making it easy for respondents to review what they have added.

When should you use a vertical subform? 

This option is useful when respondents need to carefully review what they've entered before moving on. For example, multi-attendee registrations, multi-document submissions, or any form where each entry contains a meaningful set of fields that benefit from a full-form reading experience.

Not sure which layout your respondents will prefer? 

Build with Inline first. Once the fields are finalized, switch to Popup or Vertical if the entry count grows beyond what a table row can comfortably hold.

How to add a subform to your form

Adding a subform is as simple as adding a field to your form by dragging and dropping it. 

1. Just look for the Subform field and drop it where you want it in your form. An empty subform container appears.

2. Choose your subform type in the Properties. 

   Picking the right Subform type is just the beginning. The real depth of Subforms lives in the Properties.

Subform entry limit

By default, respondents can add as many entries as they want (up to the hard cap of 120). Entry Limit lets you narrow that range with a minimum and a maximum.
You have two ways to define these limits:

Fixed values: Type in numbers directly. For example, minimum 1 and maximum 10. Clean and simple for most use cases.

Field-referenced values: Instead of typing a number, you point to another field in the form. The value a respondent enters there dynamically becomes the entry limit. This is where things get genuinely clever.
For example, your event registration form asks "How many team members are you registering?" (a Number field). Set the Subform's maximum entry limit to reference that field. Now if someone types "4", they can only add 4 attendee entries.
Setting only a maximum but no minimum means a respondent can technically submit an empty Subform. Always set a minimum of 1 if at least one entry is required for the form to make sense.

Validate duplicates in subform

Apply a "no duplicates" rule to a field. Every entry in the Subform must have a unique value in that field.

But the more powerful for real-world scenarios would be to select 2 or 3 fields as a group. An entry is only flagged as a duplicate if every field in the group matches simultaneously. Individual fields can repeat; only the full combination must be unique.

Serial numbers for subform entries

When a respondent adds several entries, it's important to keep them organized. Serial numbers add a simple but meaningful anchor: each entry is auto-labelled 1, 2, 3 and so on, giving respondents a clear count and reference point.

When someone needs to go back and edit "the third product I added", they can find it by number instead of scanning every row for the right one. For order forms, expense reports, and application forms with multiple items, serial numbers are worth enabling by default.

Sum of field entries in a subform

For forms that involve numbers like product quantities, prices, hours, scores; respondents often want to see a running total as they build their list. 

The Sum property does exactly that: it adds a totals row at the bottom of a numeric column, updating automatically as entries are added.

You can enable this on multiple numeric columns in the same subform simultaneously; for example, showing both a "Quantity" total and a "Price" total at the same time.
The sum value can be included it in Thank You page messages and email notifications so both the respondent and your team see the total in confirmation emails, not just during form-filling.
Once your subform is configured, you can style it to match your brand. 

Pro tips

Before you build your next Subform-powered form, keep these guidelines in mind:

Tip 1: Match type to field count
Use Inline for 3–4 fields, Popup when you have 6 or more, and Vertical when entry readability is a priority.

Tip 2: Use merge tags in notifications
Subform data can be included in email notifications and Thank You pages using merge tags. It renders as a formatted table, making it easy for both you and your respondents to review submissions

Tip 3: Dynamic entry limits
Instead of hardcoding "max 5 entries", reference another form field for the limit. If your form has a "How many guests are you bringing?" field, use that as the Subform's entry limit. 
 

Ready to build smarter forms?
Subforms transform Zoho Forms from a simple data-collection tool into a powerful structured-data engine for orders, registrations, applications, and beyond.