Accelerated amortization of transaction costs.

No definition available.

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

- Definition

Allocated portion of credit facility set aside for the ancillary facility.

+ References

No definition available.

+ Details

Name:	birk_AllocatedPortionOfCreditFacilityForAncillaryFacility
Namespace Prefix:	birk_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of revolving credit facility available to be drawn upon.

+ References

No definition available.

+ Details

Name:	birk_AmountOfRevolvingCreditFacilityAvailableToDrawn
Namespace Prefix:	birk_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Banking and issuance fees paid.

+ References

No definition available.

+ Details

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

- Definition

Credit facility, outstanding balance.

+ References

No definition available.

+ Details

Name:	birk_CreditFacilityOutstandingBalance
Namespace Prefix:	birk_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Embedded derivative fair value.

+ References

No definition available.

+ Details

Name:	birk_EmbeddedDerivativeFairValue
Namespace Prefix:	birk_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Repayment of revolving credit facility.

+ References

No definition available.

+ Details

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

- Definition

Revolving credit ancillary facility.

+ References

No definition available.

+ Details

Name:	birk_RevolvingCreditAncillaryFacility
Namespace Prefix:	birk_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Revolving credit facility initial aggregate commitment amount.

+ References

No definition available.

+ Details

Name:	birk_RevolvingCreditFacilityInitialAggregateCommitmentAmount
Namespace Prefix:	birk_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Transaction costs.

+ References

No definition available.

+ Details

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

- Definition

The amount of outstanding funds that the entity is obligated to repay.

+ 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

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

- Definition

The interest rate on borrowings. [Refer: Borrowings]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IFRS
-Number 7
-IssueDate 2025-01-01
-Paragraph 7
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2025-en-r&anchor=para_7&doctype=Standard
-URIDate 2025-03-27

+ Details

Name:	ifrs-full_BorrowingsInterestRate
Namespace Prefix:	ifrs-full_
Data Type:	dtr-2022:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The maturity of borrowings. [Refer: Borrowings]

+ References

+ Details

Name:	ifrs-full_BorrowingsMaturity
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with members defined in one or many axes of the table.

+ References

No definition available.

+ Details

Name:	ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	ifrs-full_ClassesOfFinancialInstrumentsAxis=birk_RevolvingCreditFacilitiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_RangeAxis=ifrs-full_TopOfRangeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_ClassesOfFinancialInstrumentsAxis=birk_NewSeniorNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_ClassesOfFinancialInstrumentsAxis=birk_OriginalSeniorNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Loans and Borrowings - Additional Information (Details) - EUR (€)				9 Months Ended
	Jun. 19, 2026	May 19, 2026	Apr. 29, 2021	Jun. 30, 2026	Mar. 09, 2026
Revolving Credit Facility
Disclosure of detailed information about borrowings [line items]
Revolving credit ancillary facility					€ 5,000,000
Repayment of revolving credit facility		€ 30,000,000
Revolving credit facility, aggregate commitment amount				€ 225,000,000
Revolving credit facility available to be drawn				€ 130,000,000
Maturity date				2029
Revolving Credit Facility \| Maximum
Disclosure of detailed information about borrowings [line items]
Credit Facility, Outstanding Balance		€ 110,000,000			€ 10,000,000
Allocated portion of credit facility, ancillary facility				€ 15,000,000
New Senior Notes
Disclosure of detailed information about borrowings [line items]
Borrowings	€ 900,000,000
Maturity date	June 15, 2033			2033
Interest rate	4.50%
Transaction costs	€ 6,000,000
Embedded derivative fair value	€ 4,900,000
Original Senior Notes
Disclosure of detailed information about borrowings [line items]
Borrowings			€ 430,000,000
Maturity date			April 30, 2029	2029
Interest rate			5.25%
Accelerated amortization of transaction costs				€ 11,700,000
Banking and issuance fees			€ 14,300,000