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

The increase (decrease) in a defined benefit obligation that would have been caused by a decrease in a significant actuarial assumption that was reasonably possible at the end of the reporting period. [Refer: Actuarial assumptions [domain]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 19
-IssueDate 2024-01-01
-Paragraph 145
-Subparagraph a
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=19&code=ifrs-tx-2024-en-r&anchor=para_145_a&doctype=Standard
-URIDate 2024-03-27

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

The increase (decrease) in a defined benefit obligation that would have been caused by an increase in a significant actuarial assumption that was reasonably possible at the end of the reporting period. [Refer: Actuarial assumptions [domain]]

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

The reasonably possible percentage of the decrease in the actuarial assumption used to determine the present value of defined benefit obligation. [Refer: Actuarial assumptions [domain]]

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

The reasonably possible percentage of the increase in the actuarial assumption used to determine the present value of defined benefit obligation. [Refer: Actuarial assumptions [domain]]

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

Name:	ifrs-full_ActuarialAssumptionsAxis=ifrs-full_ActuarialAssumptionOfLifeExpectancyAfterRetirementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	bti_RangeOfChangeInAssumptionAxis=bti_OneYearIncreaseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	bti_RangeOfChangeInAssumptionAxis=bti_OneYearDecreaseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	ifrs-full_ActuarialAssumptionsAxis=ifrs-full_ActuarialAssumptionOfExpectedRatesOfInflationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: