Note 2 - Summary of Significant Accounting Policies (Tables)

3 Months Ended

Mar. 31, 2024

Notes Tables

Schedule of Cash and Cash Equivalents [Table Text Block]

	March 31, 2024		December 31, 2023
BioLargo, Inc. and subsidiaries	$	4,242	$	3,142
Clyra Medical Technologies, Inc.		94		397
Total	$	4,336	$	3,539

Schedules of Concentration of Risk, by Risk Factor [Table Text Block]

	Three Months ended March 31,
	2024			2023
Customer A		88	%		86	%

	March 31, 2024			December 31, 2023
Customer A		79	%		68	%

Schedule of Inventory, Current [Table Text Block]

	March 31, 2024		December 31, 2023
Raw material	$	85	$	79
Finished goods		166		74
Total	$	251	$	153

Schedule of Other Assets, Noncurrent [Table Text Block]

	March 31, 2024		December 31, 2023
Patents	$	34	$	34
Security deposits		36		36
Total	$	70	$	70

Schedule of Share-Based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

	2024						2023
	Non Plan			2018 Plan			Non Plan			2018 Plan
Risk free interest rate		—	%		4.16	%		3.48	%		3.48	%
Expected volatility		—	%		99	%		114	%		114	%
Expected dividend yield		—			—			—			—
Forfeiture rate		—			—			—			—
Life in years		—			10			10			10