Note 2 - Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

Schedule of Cash and Cash Equivalents [Table Text Block]

	2018		2019
Biolargo, Inc. and subsidiaries	$	193	$	652
Clyra Medical Technologies, Inc.		462		3
Total	$	655	$	655

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

	2018			2019
Customer A		33	%		<10	%

	2018			2019
Customer B		12	%		<10	%
Customer C		31	%		<10	%
Customer D		<10	%		20	%
Customer E		<10	%		14	%
Customer F		<10	%		13	%

Schedule of Inventory, Current [Table Text Block]

	2018		2019
Raw material	$	14	$	11
Finished goods		12		5
Total	$	26	$	16

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

	2018						2019
	Non Plan			2007 Plan			Non Plan			20 18 Plan
Risk free interest rate	2.43	–	2.91%	2.89	–	2.91%	1.68	–	2.65%	1.68	–	2.65%
Expected volatility	538	–	563%	489	–	548%	133	–	152%	133	–	152%
Expected dividend yield		—			—			—			—
Forfeiture rate		—			—			—			—
Life in years		7			7			10			10