---
title: "Create and Use Subforms"
slug: "form-builder-create-and-use-subforms"
updated: 2026-10-28T14:24:15Z
published: 2026-10-28T14:24:15Z
canonical: "help.quickbase.com/form-builder-create-and-use-subforms"
---

> ## Documentation Index
> Fetch the complete documentation index at: https://help.quickbase.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Create and Use Subforms

A subform is a reusable form you add inside another form, and users can fill it out as many times as they need. This article covers how to create a subform, add it to a form, and configure it.

## How subforms work

Some data repeats an unpredictable number of times, like line items on an order, parts used on a service call, or findings on an inspection.

A subform handles this. You build the repeating group of fields once as its own form. Then you add it to a main form with the Subform field. When users fill out the main form, they complete the subform once per item. Each subform submission is its own record linked to the main submission.

Because a subform is a form in its own right, you can reuse it in as many main forms as you like.

Subforms have versions like any other form. Each main form uses a specific subform version. Publishing a new subform version doesn't change forms that use an older one until you update them.

![](https://cdn.document360.io/dd260e4e-10bb-4b66-8fb3-5504c272b904/Images/Documentation/subforms-07-preview(1).png?sv=2026-02-06&spr=https&st=2026-10-30T02%3A42%3A27Z&se=2026-10-30T03%3A42%3A27Z&sr=c&sp=r&sig=lYeSrEuLALnlp6MuOzcO674DJEHRsY5XbTS0GEMdwJ0%3D)

*A main form in the preview, with the Subform field showing the Mobile Task Subform and Tap to add*

## Create a subform on its own

1. In the portal, go to **Forms** > **My Forms**.
2. Select **New Form** > **Sub Form**.

![](https://cdn.document360.io/dd260e4e-10bb-4b66-8fb3-5504c272b904/Images/Documentation/image-1792674048232.png?sv=2026-02-06&spr=https&st=2026-10-30T02%3A42%3A27Z&se=2026-10-30T03%3A42%3A27Z&sr=c&sp=r&sig=lYeSrEuLALnlp6MuOzcO674DJEHRsY5XbTS0GEMdwJ0%3D)

*The New Form menu on the Forms page, with Sub Form selected*

1. If you're asked which builder to use, select **Form Builder**.
2. Add the fields the repeating group needs, and name the subform.
3. Select **Save Draft**, then **Publish**.

Subforms you create appear in **Forms** > **My Forms** > **Subforms**.

## Create a subform from a main form

You can also create a subform from inside the form that uses it.

1. In the Form Builder, add a Subform field. Learn how in [Add a subform to a form](/fastfield/docs/form-builder-create-and-use-subforms#add-a-subform-to-a-form).
2. In Field Settings, on the General tab, select **Create New Subform**.
3. Build the subform in the Form Builder that opens over your form.
4. Select **Save Draft**, then **Publish**.
5. Select the close icon to return to your form.

The Subform field now uses the new subform.

> [!WARNING]
> Important
> 
> Publish a subform before you rely on it. Users can't fill out an unpublished subform in the FastField mobile app.

## Add a subform to a form

1. In the Form Builder, select **Add Fields** in the side bar.
2. Under Misc, select **Subform**. You can also drag it onto the canvas where you want it.

![](https://cdn.document360.io/dd260e4e-10bb-4b66-8fb3-5504c272b904/Images/Documentation/subforms-02-add-field(1).png?sv=2026-02-06&spr=https&st=2026-10-30T02%3A42%3A27Z&se=2026-10-30T03%3A42%3A27Z&sr=c&sp=r&sig=lYeSrEuLALnlp6MuOzcO674DJEHRsY5XbTS0GEMdwJ0%3D)

*The Add Fields tab with Subform selected under Misc*

The field appears on the canvas as *Subform Field*, and its field settings open on the General tab.

![](https://cdn.document360.io/dd260e4e-10bb-4b66-8fb3-5504c272b904/Images/Documentation/subforms-03-new-field-settings(1).png?sv=2026-02-06&spr=https&st=2026-10-30T02%3A42%3A27Z&se=2026-10-30T03%3A42%3A27Z&sr=c&sp=r&sig=lYeSrEuLALnlp6MuOzcO674DJEHRsY5XbTS0GEMdwJ0%3D)

*Field Settings for a new Subform field, with Select Subform and Create New Subform*

1. In **Field Label**, enter the name users see, for example *Tasks*.
2. In **Select Subform**, select the subform.
3. Turn on **Allow Multiple Subform Instances** so users can add an entry for each item.
4. Select **Save Draft**, then **Publish**.

![](https://cdn.document360.io/dd260e4e-10bb-4b66-8fb3-5504c272b904/Images/Documentation/subforms-04-subform-selected(1).png?sv=2026-02-06&spr=https&st=2026-10-30T02%3A42%3A27Z&se=2026-10-30T03%3A42%3A27Z&sr=c&sp=r&sig=lYeSrEuLALnlp6MuOzcO674DJEHRsY5XbTS0GEMdwJ0%3D)

*Subform settings with a Subform selected, version 1, Edit Subform, Allow Multiple Subform Instances turned on, and Configure Display Mask*

> [!NOTE]
> Tip
> 
> Leave **Allow Multiple Subform Instances** off when users fill out the group of fields exactly once. You get a reusable block of fields without the option to repeat it.

> [!NOTE]
> Note
> 
> Until you select a subform, the Validation tab flags the field, because nothing would appear on the form.

## Edit a subform and keep it up to date

The version the field uses, such as *v1*, appears next to **Select Subform**.

To change the subform's fields:

1. Select the Subform field, then select **Edit Subform** in Field Settings.
2. Make your changes in the Form Builder that opens over your form.
3. Select **Save Draft**, then **Publish**.
4. Select the close icon to return to your form.

![](https://cdn.document360.io/dd260e4e-10bb-4b66-8fb3-5504c272b904/Images/Documentation/subforms-06-edit-subform(1).png?sv=2026-02-06&spr=https&st=2026-10-30T02%3A42%3A27Z&se=2026-10-30T03%3A42%3A27Z&sr=c&sp=r&sig=lYeSrEuLALnlp6MuOzcO674DJEHRsY5XbTS0GEMdwJ0%3D)

*The Mobile Task Subform open in the Form Builder over the main form, with the close icon highlighted*

When you close the subform, the Subform field updates to its latest version. Select **Save Draft** and **Publish** on the main form so users get the change.

If the subform has a newer published version, an update button, such as **Update to v2**, appears next to the version number. Select it to use the latest version in this form.

## Name each instance

Subform entries look alike in a list. Set a display mask so each one shows its own values, for example the task name.

1. In the Subform field's settings, select **Configure Display Mask**.
2. Under Add Field, select the subform fields you want in the name. Use **Search fields...** to find a field.
3. Select **Back to Field** when you're done.

![](https://cdn.document360.io/dd260e4e-10bb-4b66-8fb3-5504c272b904/Images/Documentation/subforms-05-display-mask(1).png?sv=2026-02-06&spr=https&st=2026-10-30T02%3A42%3A27Z&se=2026-10-30T03%3A42%3A27Z&sr=c&sp=r&sig=lYeSrEuLALnlp6MuOzcO674DJEHRsY5XbTS0GEMdwJ0%3D)

*The Subform Display Mask panel with the Task field added to the display mask*

After you set a mask, the button changes to **Edit Display Mask**.

## Convert a page into a subform

If you've already built the repeating fields as a page in your form, you don't have to rebuild them.

1. In the Form Builder, select **Actions** in the toolbar, then **Convert Page To Subform**.
2. Check the page name next to Page to convert.
3. In **New Sub Form Name**, enter a name.
4. Select **Convert**.

![](https://cdn.document360.io/dd260e4e-10bb-4b66-8fb3-5504c272b904/Images/Documentation/subforms-08-convert-page(1).png?sv=2026-02-06&spr=https&st=2026-10-30T02%3A42%3A27Z&se=2026-10-30T03%3A42%3A27Z&sr=c&sp=r&sig=lYeSrEuLALnlp6MuOzcO674DJEHRsY5XbTS0GEMdwJ0%3D)

*The Convert Current Page To Subform panel, with the page to convert and the New Sub Form Name box*

> [!WARNING]
> Important
> 
> This always converts the first page of your form, even if you're working on another page. To convert a different page, move it to the first position first.

FastField creates the subform right away. Your main form doesn't change. To use the new subform, add a Subform field and select it, then remove the original page if you no longer need it.

## Set up subforms with the Assistant

You can also ask the Assistant to add a Subform field or to turn a section into a subform.

1. Select **Assistant** in the side bar.
2. Describe what you want, for example *Add a subform field for Mobile Task Subform after Description and allow multiple instances* or *Convert the Tasks section into a subform called Task Details*.
3. Send the message.

The Assistant can add a Subform field that uses an existing subform, allow multiple instances, set a display mask, and convert a section into a new subform.

> [!WARNING]
> Important
> 
> When the Assistant converts a section or creates a new subform, FastField creates that subform right away, even if you don't select **Save Draft** on the main form.

The Assistant in your main form can't change the fields inside a subform. To do that, select **Edit Subform**, then use the Assistant in the subform.

> [!NOTE]
> Note
> 
> Changes to the main form aren't saved until you select **Save Draft**.

## Notes and limitations

- A subform can't contain another Subform field. Subforms don't nest.
- Subforms don't have pages, only sections and fields.
- Subform data can't be exported to CSV.
- Custom Word and PDF report templates don't support repeating sections inside subforms, or subforms inside repeating sections. Don't use both together.

## What's next

- [Add a table to a form (using subforms)](/fastfield/docs/en/form-builder-add-a-table-to-a-form-using-subforms)
- [Create and use repeating sections](/fastfield/docs/en/form-builder-create-and-use-repeating-sections)
- [Subforms introduction](/fastfield/docs/en/subforms-introduction)