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Auto Number

Auto Number is a custom field type in Salesforce that automatically generates a unique, sequential number for each new record created on an object.

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Definition

Auto Number is a custom field type in Salesforce that automatically generates a unique, sequential number for each new record created on an object. Administrators define the display format (such as a prefix and number of digits, like 'CASE-{0000}'), and Salesforce increments the number automatically. Auto Number fields are commonly used for Case numbers, Invoice numbers, and other identifiers that require unique sequential values.

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In plain English

👋 Study buddy

Auto Number is a field type that generates a unique sequential number for every new record automatically. You've probably seen Case numbers like 00001234, 00001235. That's Auto Number doing its thing: incrementing the number by one every time a new record is created.

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Worked example

scenario · real-world use

Riverbend Auto adds a custom Service_Ticket__c object for their service department. The Record Name is configured as Auto Number with format SVC-{0000} starting at 1. The first ticket created gets SVC-0001, the next SVC-0002, and so on. Service techs reference tickets by their auto-number ID over the radio ("working on SVC-1247"), customers see it on receipts, and the tickets sort cleanly by creation order in reports. Auto Number is the trivial, automatic alternative to humans typing identifiers - and unlike a manually-entered Name field, two service techs can't accidentally create tickets with the same number.

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Why Auto Number matters

Auto Number is a custom field type on Salesforce objects that generates a unique, sequential value for each new record. When configuring an Auto Number field, administrators specify a display format (like CASE-{00000} which produces CASE-00001, CASE-00002, and so on) and a starting value. Salesforce then increments the number automatically whenever a new record is created, and the value is set once and cannot be changed afterward.

Auto Number fields are commonly used for human-readable identifiers like Case Numbers, Invoice Numbers, Project Codes, and Ticket IDs where users need a unique reference that's shorter and more memorable than a Salesforce record ID. One important thing to know: Auto Number sequences can have gaps when record creation fails mid-transaction or when records are deleted, so they should not be used as audit trails that require no gaps. For that, you need different patterns.

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How to create Auto Number

Auto Number is a custom field type that generates a unique, sequential number for each new record — "INV-{0001}," "CASE-{0000000}," "PRJ-{0000}." Salesforce increments automatically; admins control the display format. Common for invoice numbers, ticket numbers, and any identifier that needs sequential uniqueness.

  1. Open Setup → Object Manager → [object] → Fields & Relationships → New

    Auto Number is a field type, created the same way as any custom field.

  2. Pick Auto Number as the Data Type

    From the field type picker. Auto Number is locked at field creation — you can't convert another type to Auto Number later.

  3. Set Display Format

    Format string with {0} placeholders: 'INV-{0000}' produces INV-0001, INV-0002, etc. Leading zeros pad the number to the format width.

  4. Set Starting Number

    Where the sequence starts. Default 1. Useful for migrations: pick a starting number above your existing data so new records don't collide.

  5. Set Field Label and Field Name

    Standard custom field metadata.

  6. Tick External ID (optional but recommended)

    Marks the field as searchable / unique-indexable. Useful if external systems use this number as a join key.

  7. Save

    Field is created. New records get the next number automatically; existing records get NULL until you bulk-populate.

Mandatory fields
Display Formatrequired

Required. Format string with {0} placeholder.

Starting Numberrequired

Required. Default 1.

Field Label and Namerequired

Required. Same as any custom field.

Gotchas
  • Auto Number fields don't populate retroactively. Existing records get NULL when you add the field — bulk-populate via Data Loader if needed (use a starting number high enough to avoid collisions with new records).
  • Display Format is locked after Save. Switching from 'INV-{0000}' to 'INV-{00000}' (more digits) requires deleting and recreating — losing all existing values.
  • Auto Number is text, not numeric. Sorting by auto number sorts alphabetically — INV-0010 sorts before INV-002 unless you pad with leading zeros.
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How organizations use Auto Number

Redwood Financial

Uses Auto Number fields on a custom Invoice__c object with the format INV-{YYYY}-{0000}. Each invoice gets a year-prefixed sequential number that's easy for customers and AP staff to reference verbally.

NovaScale

Configured an Auto Number field as the primary display name for their Work Order custom object. Field technicians reference work orders by number in radio calls and paperwork, so a clean, unique identifier matters.

Cyberdyne Co

Learned the hard way that Auto Number gaps are expected. Their finance team raised an alarm when invoice numbers skipped from 1044 to 1046, but the missing number was just a cancelled save, not lost data.

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Trust & references

Official documentation

Straight from the source - Salesforce's reference material on Auto Number.

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Test your knowledge

Q1. What does an Auto Number field do?

Q2. Can Auto Number sequences have gaps?

Q3. Which of these is a common use for Auto Number fields?

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