Note 2 - Summary of Significant Accounting Policies (Tables)

9 Months Ended

Sep. 30, 2025

Notes Tables

Schedule of Cash and Cash Equivalents [Table Text Block]

	September 30, 2025		December 31, 2024
BioLargo, Inc. and subsidiaries	$	2,345	$	3,175
Clyra Medical Technologies, Inc.		2,201		373
Total	$	4,546	$	3,548

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

	Three Months Ended September 30,						Nine Months Ended September 30,
	2025			2024			2025			2024
Customer A		35	%		76	%		64	%		78	%

	September 30, 2025			December 31, 2024
Customer A		—			82	%
Customer B		38	%		—

Schedule of Inventory, Current [Table Text Block]

	September 30, 2025		December 31, 2024
Raw material	$	251	$	210
Finished goods		158		120
Total	$	409	$	330

Schedule of Other Assets, Noncurrent [Table Text Block]

	September 30, 2025		December 31, 2024
Patents	$	34	$	34
Security deposits		72		61
Interest receivable		10		—
Total	$	116	$	95

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

	2025						2024
	Non Plan			2024 Plan			Non Plan			2018 Plan			2024 Plan
Risk free interest rate		4.23	%		3.69 - 4.58	%		3.81 - 4.34	%		4.16	%		3.75 - 4.58	%
Expected volatility		91	%		87 - 91	%		95 - 117	%		99 - 102	%		95 - 96	%
Expected dividend yield		—			—			—			—			—
Forfeiture rate		—			—			—			—			—
Life in years		10			10			10			10			10

Property, Plant and Equipment [Table Text Block]

	September 30, 2025			December 31, 2024
Equipment	$	1,711		$	1,678
Leasehold improvements		526			526
Total, at cost		2,237			2,204
Less: accumulated depreciation		(573	)		(462	)
Total equipment and leasehold improvements, net	$	1,664		$	1,742