Cover - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Mar. 13, 2025	Jun. 28, 2024
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2024
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-35633
Entity Registrant Name	Sound Financial Bancorp, Inc.
Entity Incorporation, State or Country Code	MD
Entity Tax Identification Number	45-5188530
Entity Address, Address Line One	2400 3rd Avenue,
Entity Address, Address Line Two	Suite 150,
Entity Address, City or Town	Seattle,
Entity Address, State or Province	WA
Entity Address, Postal Zip Code	98121
City Area Code	206
Local Phone Number	448-0884
Title of 12(b) Security	Common Stock, par value $0.01 per share
Trading Symbol	SFBC
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	false
Document Financial Statement Error Correction	false
Entity Shell Company	false
Entity Public Float			$ 57.0
Entity Common Stock, Shares Outstanding		2,566,069
Documents Incorporated by Reference	PART III of Form 10-K – Portions of the Registrant's Proxy Statement for its 2025 Annual Meeting of Stockholders. The 2025 Proxy Statement will be filed with the U.S. Securities and Exchange Commission within 120 days after the end of the fiscal year to which this report relates.
Entity Central Index Key	0001541119
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	FY
Amendment Flag	false