Note 5 - Share-based Compensation (Details Textual) - USD ($)					3 Months Ended				6 Months Ended
	Jan. 31, 2025	Aug. 13, 2024	Jun. 22, 2018	Sep. 07, 2017	Jun. 30, 2025	Mar. 31, 2025	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2025	Jun. 30, 2024
Stock Issued During Period, Value, Issued for Services					$ 212,000	$ 61,000	$ 116,000	$ 83,000
Share Price (in dollars per share)					$ 0.21				$ 0.21
2024 Equity Incentive Plan [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Expiration Period (Year)									10 years
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized Per Year (in shares)									2,000,000
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Authorized (in shares)					42,000,000				42,000,000
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Available for Grant (in shares)					32,715,733				32,715,733
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Gross (in shares)						3,790,347		1,829,757
Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Grants in Period, Weighted Average Exercise Price (in dollars per share)						$ 0.24		$ 0.26
2018 Equity Incentive Plan [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Expiration Period (Year)			10 years
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Available for Grant (in shares)							9,343,614			9,343,614
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Gross (in shares)								1,547,938
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount					$ 435,000				$ 435,000
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)									4 years
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercises in Period (in shares)					566,951			497,024	566,951
Stock Issued During Period, Shares, Cashless Exercise of Options (in shares)									265,800
Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Grants in Period, Weighted Average Exercise Price (in dollars per share)								$ 0.3
Equity Incentive Plan 2007 [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Expiration Period (Year)				10 years
Non Plan [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Gross (in shares)						32,143		15,686
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercises in Period (in shares)								463,882
Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Grants in Period, Weighted Average Exercise Price (in dollars per share)						$ 0.28		$ 0.26
Share-Based Payment Arrangement, Option [Member] \| 2024 Equity Incentive Plan [Member]
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount					$ 438,000				$ 438,000
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)						4 years
Share-Based Payment Arrangement, Option [Member] \| Non Plan [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Gross (in shares)									32,143	15,686
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Fair Value									$ 8,000	$ 4,000
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount					55,000		$ 109,000		$ 55,000	$ 109,000
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)									1 year	4 years
Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Grants in Period, Weighted Average Exercise Price (in dollars per share)									$ 0.28	$ 0.26
Proceeds from Issuance of Common Stock							$ 85,000
Stock Issued During Period, Shares, New Issues (in shares)							497,024
Share-Based Payment Arrangement, Option [Member] \| Clyra Medical Technologies [Member]
Share-Based Payment Arrangement, Expense					200,000		$ 63,000		$ 406,000	$ 122,000
Share-Based Payment Arrangement, Option [Member] \| Selling, General and Administrative Expenses [Member]
Share-Based Payment Arrangement, Expense					$ 492,000		$ 539,000		$ 1,107,000	$ 1,027,000
Officer [Member]
Stock Issued During Period, Shares, Issued for Services (in shares)					350,751	11,250		0
Shares Issued, Price Per Share (in dollars per share)					$ 0.21	$ 0.28			$ 0.21
Stock Issued During Period, Value, Issued for Services					$ 70,000	$ 3,000
Consultants [Member]
Stock Issued During Period, Shares, Issued for Services (in shares)					564,252	209,080	446,989	288,997
Shares Issued, Price Per Share (in dollars per share)					$ 0.21	$ 0.28	$ 0.26	$ 0.35	$ 0.21	$ 0.26
Stock Issued During Period, Value, Issued for Services					$ 143,000	$ 58,000	$ 116,000	$ 83,000
Consultants [Member] \| 2024 Equity Incentive Plan [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Gross (in shares)									1,508,203	338,241
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Fair Value									$ 328,000	$ 77,000
Board of Directors, Employees, and Consultants [Member] \| 2024 Equity Incentive Plan [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Gross (in shares)									3,790,347	1,829,757
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Fair Value									$ 816,000	$ 428,000
Board of Directors, Employees, and Consultants [Member] \| 2018 Equity Incentive Plan [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Gross (in shares)								1,547,938
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Fair Value								$ 418,000
Board of Directors, Employees, and Consultants [Member] \| Replacement Options [Member] \| 2018 Equity Incentive Plan [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Gross (in shares)								544,841
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Fair Value								$ 173,000
Director [Member] \| 2024 Equity Incentive Plan [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Gross (in shares)									822,571	367,648
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Fair Value									$ 172,000	$ 84,000
Director [Member] \| 2018 Equity Incentive Plan [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Gross (in shares)								267,746
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Fair Value								$ 85,000
Employees [Member] \| Employee Retention Program [Member] \| 2024 Equity Incentive Plan [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Gross (in shares)									1,159,573	423,868
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Fair Value									$ 249,000	$ 98,000
Employees [Member] \| Employee Retention Program [Member] \| 2018 Equity Incentive Plan [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Gross (in shares)								735,351
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Fair Value								$ 160,000
Chief Financial Officer [Member] \| 2024 Equity Incentive Plan [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Gross (in shares)									300,000	700,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Fair Value									$ 67,000	$ 169,000
Chief Financial Officer [Member] \| Share-Based Payment Arrangement, Option [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Expiration Period (Year)	10 years	10 years
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Gross (in shares)	300,000	300,000
Engagement Extension, Term (Year)	1 year	1 year
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross, Per Month (in shares)	25,000	25,000
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 0.2536	$ 0.24
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Available Grants in Period, Gross, Upon Renewal (in shares)		300,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vesting Period for Renewable Options (Year)		1 year

BIOLARGO, INC. 10-Q