Cabaletta Bio, Inc. Quarterly report pursuant to Section 13 or 15(d)

Quarterly report pursuant to Section 13 or 15(d)

Cover
- Document and Entity Information
Financial Statements
Notes to Financial Statements
Accounting Policies
- Summary of Significant Accounting Policies (Policies)
Notes Tables
Notes Details

Basis of Presentation - Additional Information (Details)

v3.19.3

Basis of Presentation - Additional Information (Details) $ / shares in Units, $ in Thousands			1 Months Ended	9 Months Ended
	Oct. 29, 2019 USD ($) $ / shares shares	Oct. 16, 2019 $ / shares	Nov. 30, 2019 USD ($) shares	Sep. 30, 2019 USD ($) $ / shares shares	Oct. 30, 2019 shares	Dec. 31, 2018 $ / shares shares
Basis Of Presentation [Line Items]
Reverse stock split description				1-for-1.5 reverse split
Common stock, par value \| $ / shares				$ 0.00001		$ 0.00001
Net proceeds from initial public offering \| $				$ 71,028
Common stock, outstanding shares				3,848,320		3,848,320
Subsequent Event
Basis Of Presentation [Line Items]
Reverse stock split ratio		0.67
Common stock, par value \| $ / shares		$ 0.00001
Net proceeds from initial public offering \| $			$ 4,864
Common stock, outstanding shares					23,552,854
Number of additional common stock purchased by underwriters upon partial exercise of option			475,501
Subsequent Event \| Initial Public Offering
Basis Of Presentation [Line Items]
Issuance of common stock, shares	6,800,000
Common stock issued, per share \| $ / shares	$ 11.00
Net proceeds from initial public offering \| $	$ 66,164
Conversion of convertible preferred stock to common stock	12,904,534

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