Document and Entity Information - shares	6 Months Ended
	Mar. 31, 2022	May 03, 2022
Cover [Abstract]
Entity Registrant Name	PHX MINERALS INC.
Entity Central Index Key	0000315131
Document Type	10-Q
Document Period End Date	Mar. 31, 2022
Amendment Flag	false
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q2
Current Fiscal Year End Date	--09-30
Entity Filer Category	Non-accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	true
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Shell Company	false
Entity File Number	001-31759
Entity Tax Identification Number	73-1055775
Entity Address, Address Line One	1601 NW Expressway
Entity Address, Address Line Two	Suite 1100
Entity Address, City or Town	Oklahoma City
Entity Address, State or Province	OK
Entity Address, Postal Zip Code	73118
City Area Code	405
Local Phone Number	948-1560
Entity Incorporation, State or Country Code	DE
Document Quarterly Report	true
Document Transition Report	false
Entity Common Stock, Shares Outstanding		35,225,891
Title of each class	Common Stock, $0.01666 par value
Trading Symbol(s)	PHX
Name of each exchange on which registered	NYSE