Note 2 - Summary of Significant Accounting Policies (Tables)

6 Months Ended

Jun. 30, 2023

Notes Tables

Schedule of Cash and Cash Equivalents [Table Text Block]

	June 30, 2023		December 31, 2022
BioLargo, Inc. and subsidiaries	$	2,762	$	1,681
Clyra Medical Technologies, Inc.		813		170
Total	$	3,575	$	1,851

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

	Three Months						Six Months
	June 30, 2023			June 30, 2022			June 30, 2023			June 30, 2022
Customer A		55	%		39	%		77	%		35	%
Customer B	<10		%		27	%	<10		%		17	%
Customer C	<10		%	<10		%	<10		%		10	%

	June 30, 2023			December 31, 2022
Customer A		49	%		11	%
Customer B	<10		%		31	%
Customer D	<10		%		15	%

Schedule of Inventory, Current [Table Text Block]

	June 30, 2023		December 31, 2022
Raw material	$	83	$	46
Finished goods		44		74
Total	$	127	$	120

Schedule of Other Assets, Noncurrent [Table Text Block]

	June 30, 2023		December 31, 2022
Patents	$	34	$	34
Security deposits		35		35
Tax credit receivable		--		55
Total	$	69	$	124

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

	2023						2022
	Non Plan			2018 Plan			Non Plan			2018 Plan
Risk free interest rate	3.48	–	3.58%	3.48	–	3.58%	2.32	–	3.83%	2.32	–	2.98%
Expected volatility	113	-	114%	113	-	114%	114	–	117%	116	–	117%
Expected dividend yield	—			—			—			—
Forfeiture rate	—			—			—			—
Life in years	10			10			10			10