Note 1 - Business and Organization (Details Textual)	3 Months Ended
	Mar. 31, 2023 USD ($)	Mar. 31, 2022 USD ($)	Dec. 31, 2022 USD ($)	Sep. 30, 2017
Number of Wholly-Owned Subsidiaries	5
Revenue from Contract with Customer, Including Assessed Tax	$ 3,742,000	$ 965,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	(494,000)	(1,544,000)
Net Cash Provided by (Used in) Operating Activities	(43,000)	(1,140,000)
Working Capital (Deficit)	3,075,000
Assets, Current	4,874,000		$ 3,153,000
Stock Issued During Period, Value, New Issues	800,000	$ 1,202,000
Cash and Cash Equivalents, at Carrying Value	3,264,000		$ 1,851,000
SBA CARES Act Paycheck Protection Program [Member]
Long-Term Debt	140,000
Economic Injury Disaster Loan [Member]
Long-Term Debt	150,000
Inventory Line of Credit [Member] | Clyra Medical Technologies [Member]
Long-Term Line of Credit	247,000
Vehicle Loan [Member]
Long-Term Debt	78,000
The 2020 Unit Offering [Member]
Stock Issued During Period, Value, New Issues	695,000
Lincoln Park Capital Fund, LLC [Member]
Stock Issued During Period, Value, New Issues	$ 105,000
BioLargo Engineering, Science & Technologies, LLC [Member]
Noncontrolling Interest, Ownership Percentage by Parent	82.25%			100.00%
Clyra Medical Technologies [Member]
Noncontrolling Interest, Ownership Percentage by Parent	58.00%
Noncontrolling Interest, Increase from Subsidiary Equity Issuance	$ 225,000
BioLargo Energy Technologies, Inc (BETI) [Member]
Noncontrolling Interest, Ownership Percentage by Parent	97.10%
Noncontrolling Interest, Increase from Subsidiary Equity Issuance	$ 550,000