Get Started Free A Lookup Relationship in Salesforce loosely links two objects so the child can reference the parent, but each object keeps its own owner, sharing, and lifecycle. Unlike Master-Detail, the child can exist independently of the parent. If the parent record is deleted, the outcome depends on the lookup relationship’s delete behavior: Salesforce can clear the lookup field, prevent the deletion, or delete the child record where cascade delete is supported. Lookup relationships do not support roll-up summary fields on the parent. They can link two different objects or an object to itself.
You’ll meet this term whenever a child object can exist independently of the parent: a PTO Request linked to a User, a Case linked to a Contact, an Asset linked to an Account.
PRACTICAL EXAMPLE
An IT operations team uses a custom Asset object to track company hardware (laptops, monitors, servers). Each asset references its owning department through Lookup Relationship to the Account object. The asset and the department exist independently: an asset can be reassigned to another department without losing its history, and a department is not deleted when its asset is retired.
Quick facts
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Loose coupling: child record has its own Owner, sharing, and security settings. The child survives if the parent is deleted (depending on field settings).
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Three options when the parent is deleted: Clear the value (default), Don’t allow deletion of the lookup record, or Delete this record also (cascade-delete).
Note: cascade-delete is disabled by default and requires Salesforce Support to enable it for an org. -
No roll-up summary support: roll-up summaries (Count, Sum, Min, Max) work only with Master-Detail relationships, not Lookups.
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Can link two different objects, or an object to itself. Self-relationships are useful for hierarchies (e.g., Bug to related Bug). The User object cannot be used in a self-lookup; use Hierarchical Relationship for that.
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40 total relationships per custom object (Lookups and Master-Detail combined).
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Cascade-delete not available for lookups to: business hours, network, lead, price book, product, user.
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100,000 records ceiling for deletion: cannot delete an object or record in a Lookup if the combined number of records between the two linked objects exceeds 100,000. Delete child records first to bring the total below the limit.
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Lookup field can be required: if set as required on save, the relationship behaves like a softer Master-Detail (child cannot be saved without parent), but without sharing/owner inheritance and without roll-up summary.
Note
Some Salesforce relationships are Lookup, including Account to Contact and Account to Opportunity, even though they appear to be tight parent-child relationships. The exception is Opportunity Line Item to Opportunity, which behaves like Master-Detail but is technically defined as Lookup. When deciding between Lookup and Master-Detail for a custom object: use Lookup when the child can exist without the parent; use Master-Detail only when you need cascade delete, security inheritance, or roll-up summary fields.
