Custom Field
A Custom Field is a field created by an administrator on any standard or custom object to capture data specific to the organization's needs.
Definition
A Custom Field is a field created by an administrator on any standard or custom object to capture data specific to the organization's needs. Salesforce supports many custom field types including text, number, date, picklist, formula, lookup, and more. Custom field API names end with "__c".
In plain English
“Here's a simple way to think about it: every Salesforce org's identity is written in Custom Fields. Region, Customer Tier, Renewal Date - added because the standard schema didn't capture it. The `__c` suffix marks fields specific to your business.”
Worked example
At Horizon Software, an admin adds a Custom Field called Renewal_Risk__c to the Account object - a picklist with values Low, Medium, High - and configures a Flow that writes to it nightly based on product-usage data from Data Cloud. The API name comes out as Renewal_Risk__c (the "__c" suffix is automatic on custom fields); the Flow uses that name to write, and reports and list views reference it as a filterable field. Six months in, the field drives the CS team's weekly save-call list and is treated as a core attribute of the Account, indistinguishable in practice from standard fields like Industry.
Why every Salesforce org's identity is written in Custom Fields
Out of the box, Salesforce gives you a generic Account, Contact, Opportunity, and Case. The reason no two orgs look alike is the Custom Field - every "Region", "Customer Tier", "Renewal Date", "Contract ID", and "Internal Notes" you see on a record was added by someone, on purpose, because the standard schema didn't capture it. The API-name suffix `__c` is the platform's way of marking which fields belong to your business specifically.
That power is why field hygiene becomes a real problem in any long-lived org. A Custom Field is easy to create, hard to remove (something always references it), and impossible to consolidate without a migration project. Strong admin teams treat new field requests like database schema changes - they ask whether an existing field would do, they require a description on every new field, and they audit unused fields on a release cadence. The org you inherit five years from now will be the sum of these small decisions; this is where most of that surface gets created.
How to create Custom Field
Custom Fields are how you extend a Salesforce object beyond its standard fields — text fields, numbers, picklists, formulas, lookups. The data type is locked once chosen; pick carefully. Each custom field gets a __c suffix in its API name.
- Open Setup → Object Manager → [object] → Fields & Relationships
Pick the object the field belongs on — Standard or Custom.
- Click New
Top-right of the field list.
- Pick the Data Type
Text / Number / Date / DateTime / Currency / Picklist / Checkbox / Formula / Lookup / Master-Detail / Roll-Up Summary / and more. Locked after Save — to change, recreate.
- Set field-type-specific details
Text: Length. Number: Precision/Scale. Picklist: values list. Formula: return type and expression. Lookup: target object.
- Set Field Label and Field Name
Label is user-facing. Field Name is the API name with __c appended (e.g., Account.Industry__c).
- Set Help Text and Description
Help Text shows the ? icon next to the field for users. Description is admin-only documentation.
- Configure Field-Level Security
Per-profile Visible / Read-Only checkboxes. Modern best practice is to leave most profiles untouched and grant via Permission Sets.
- Add to Page Layouts → Save
The final step adds the field to chosen page layouts. Forget this and the field exists but no one sees it.
Required. UI name.
Required. Auto-derived; __c appended.
Required. Locked after Save.
- Data type is locked after Save. Changing from Text to Number means deleting the field and creating a new one — losing references, formulas, and any data. Pick the right type upfront.
- Custom Field limits per object are real (varies by edition, typically ~500 active custom fields). Hitting the limit blocks new fields — must delete unused fields or upgrade edition.
- Adding to Page Layouts is the step that's forgotten most often. The field exists in Object Manager but doesn't appear on records until added to the layouts users actually see.
How organizations use Custom Field
Quarterly Custom Field audit retired 200+ unused fields; admin debt reduced meaningfully.
Field hygiene practiced as standard; new fields require description and business justification.
Related free tool
Trust & references
Straight from the source - Salesforce's reference material on Custom Field.
- Create a Custom FieldSalesforce Help
- Custom Field TypesSalesforce Help
Test your knowledge
Q1. Can a Salesforce admin configure Custom Field without writing code?
Q2. In which area of Salesforce would you typically find Custom Field?
Q3. What is the primary benefit of Custom Field for Salesforce administrators?
Discussion
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