Note 1 - Business and Organization (Details Textual)	12 Months Ended
	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Sep. 30, 2017
Revenues	$ 12,230,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	(4,648,000)	$ (5,132,000)
Net Cash Provided by (Used in) Operating Activities	(2,365,000)	(2,762,000)
Working Capital (Deficit)	3,652,000
Assets, Current	6,362,000	3,153,000
Stock Issued During Period, Value, New Issues	2,153,000	3,617,000
Proceeds from Issuance of Preferred Stock and Preference Stock	$ 1,575,000	$ 225,000
Number of Wholly-Owned Subsidiaries	5
BioLargo Energy Technologies, Inc (BETI) [Member]
Subsidiary, Ownership Percentage, Parent	96.00%
Clyra Medical Technologies [Member]
Subsidiary, Ownership Percentage, Parent	53.00%
BioLargo Engineering, Science & Technologies, LLC [Member]
Subsidiary, Ownership Percentage, Parent	82.00%		100.00%
Clyra Medical Common Stock [Member]
Proceeds from Issuance or Sale of Equity	$ 35,000
BETI Common Stock [Member]
Proceeds from Issuance or Sale of Equity	1,005,000
BETI Common Stock [Member] | Conversion Debt to Equity [Member]
Debt Conversion, Converted Instrument, Amount	50,000
Lincoln Park Capital Fund, LLC [Member]
Stock Issued During Period, Value, New Issues	995,000
The 2020 Unit Offering [Member]
Stock Issued During Period, Value, New Issues	1,158,000
Biolargo [Member] | BETI Common Stock [Member]
Proceeds from Issuance or Sale of Equity	$ 100,000