Government Grant - Summary of Government Grant (Details) - EUR (€) € in Thousands	12 Months Ended
Sep. 30, 2025	Sep. 30, 2024
Government Grant [Line Item]
Government Grants, Beginning balance		€ 11,300
Government Grant
Government Grant [Line Item]
Government Grants, Beginning balance	€ 10,374	10,634
Pledged during the year	0	239
Released to the statement of comprehensive income	(505)	(499)
Government Grants, Ending balance	9,869	10,374
thereof current	0	0
thereof non-current	€ 9,869	€ 10,374

Government Grant.

No definition available.

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Namespace Prefix:	birk_
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Period Type:	duration

- Definition

Government grant pledged during the year.

+ References

No definition available.

+ Details

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Namespace Prefix:	birk_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Government grant released to statement of comprehensive income.

+ References

No definition available.

+ Details

Name:	birk_GovernmentGrantReleasedToStatementOfComprehensiveIncome
Namespace Prefix:	birk_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of current government grants recognised in the statement of financial position as deferred income. [Refer: Government [member]; Government grants]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Note Expiry date 2027-01-01
-Name IAS
-Number 1
-IssueDate 2025-01-01
-Paragraph 55
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2025-en-b&anchor=para_55&doctype=Standard
-URIDate 2025-03-27

+ Details

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Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The amount of assistance by government in the form of transfers of resources to an entity in return for past or future compliance with certain conditions relating to the operating activities of the entity, recognised as deferred income. They exclude those forms of government assistance that cannot reasonably have a value placed upon them and transactions with government that cannot be distinguished from the normal trading transactions of the entity. [Refer: Deferred income other than contract liabilities; Government [member]]

+ References

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

The amount of non-current government grants recognised on the statement of financial position as deferred income. [Refer: Government [member]; Government grants]

+ References

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

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