Offerings	Mar. 05, 2026 USD ($) shares
Offering: 1
Offering:
Fee Previously Paid	false
Other Rule	true
Security Type	Equity
Security Class Title	2021 Equity Incentive Plan Common Stock, $0.0001 par value per share
Amount Registered \| shares	4,757,184
Proposed Maximum Offering Price per Unit	1.765
Maximum Aggregate Offering Price	$ 8,396,429.76
Fee Rate	0.01381%
Amount of Registration Fee	$ 1,159.55
Offering Note	(1) Pursuant to Rule 416(a) under the Securities Act of 1933, as amended (the "Securities Act"), this registration statement shall also cover any additional shares of the Registrant's common stock that become issuable under the Caribou Biosciences, Inc. 2021 Equity Incentive Plan ("2021 EIP") and the Caribou Biosciences, Inc. 2021 Employee Stock Purchase Plan ("2021 ESPP") by reason of any stock dividend, stock split, recapitalization or similar transaction effected without the Registrant's receipt of consideration which would increase the number of outstanding shares of common stock. Additionally, pursuant to Rule 416(b) under the Securities Act, if prior to the completion of the distribution of the securities registered under this registration statement, all the securities of a class, which includes the registered securities, are combined by a reverse stock split into a lesser number of securities of the same class, the number of undistributed securities of such class deemed covered by this registration statement shall be proportionately reduced. (2) Represents additional shares of Common Stock reserved for issuance under the 2021 EIP. (3) Estimated in accordance with Rules 457(c) and 457(h) under the Securities Act solely for the purpose of calculating the registration fee on the basis of $1.765 per share, which is the average of the high and low prices of the Registrant's common stock, as reported on the Nasdaq Global Select Market, on March 3, 2026.
Offering: 2
Offering:
Fee Previously Paid	false
Other Rule	true
Security Type	Equity
Security Class Title	2021 Employee Stock Purchase Plan Common Stock, $0.0001 par value per share
Amount Registered \| shares	951,436
Proposed Maximum Offering Price per Unit	1.765
Maximum Aggregate Offering Price	$ 1,679,284.54
Fee Rate	0.01381%
Amount of Registration Fee	$ 231.91
Offering Note	(1) Pursuant to Rule 416(a) under the Securities Act of 1933, as amended (the "Securities Act"), this registration statement shall also cover any additional shares of the Registrant's common stock that become issuable under the Caribou Biosciences, Inc. 2021 Equity Incentive Plan ("2021 EIP") and the Caribou Biosciences, Inc. 2021 Employee Stock Purchase Plan ("2021 ESPP") by reason of any stock dividend, stock split, recapitalization or similar transaction effected without the Registrant's receipt of consideration which would increase the number of outstanding shares of common stock. Additionally, pursuant to Rule 416(b) under the Securities Act, if prior to the completion of the distribution of the securities registered under this registration statement, all the securities of a class, which includes the registered securities, are combined by a reverse stock split into a lesser number of securities of the same class, the number of undistributed securities of such class deemed covered by this registration statement shall be proportionately reduced. (2) Represents additional shares of Common Stock reserved for issuance under the Registrant's 2021 ESPP. (3) Estimated in accordance with Rules 457(c) and 457(h) under the Securities Act solely for the purpose of calculating the registration fee on the basis of $1.765 per share, which is the average of the high and low prices of the Registrant's common stock, as reported on the Nasdaq Global Select Market, on March 3, 2026.

Offerings

Mar. 05, 2026

USD ($)

Offering:

false

true

Equity

2021 Equity Incentive Plan Common Stock, $0.0001 par value per share

Amount Registered | shares

4,757,184

Proposed Maximum Offering Price per Unit

1.765

Maximum Aggregate Offering Price

$ 8,396,429.76

Fee Rate

0.01381%

Amount of Registration Fee

$ 1,159.55

Offering Note

(1) Pursuant to Rule 416(a) under the Securities Act of 1933, as amended (the "Securities Act"), this registration statement shall also cover any additional shares of the Registrant's common stock that become issuable under the Caribou Biosciences, Inc. 2021 Equity Incentive Plan ("2021 EIP") and the Caribou Biosciences, Inc. 2021 Employee Stock Purchase Plan ("2021 ESPP") by reason of any stock dividend, stock split, recapitalization or similar transaction effected without the Registrant's receipt of consideration which would increase the number of outstanding shares of common stock. Additionally, pursuant to Rule 416(b) under the Securities Act, if prior to the completion of the distribution of the securities registered under this registration statement, all the securities of a class, which includes the registered securities, are combined by a reverse stock split into a lesser number of securities of the same class, the number of undistributed securities of such class deemed covered by this registration statement shall be proportionately reduced. (2) Represents additional shares of Common Stock reserved for issuance under the 2021 EIP. (3) Estimated in accordance with Rules 457(c) and 457(h) under the Securities Act solely for the purpose of calculating the registration fee on the basis of $1.765 per share, which is the average of the high and low prices of the Registrant's common stock, as reported on the Nasdaq Global Select Market, on March 3, 2026.

Offering:

false

true

Equity

2021 Employee Stock Purchase Plan Common Stock, $0.0001 par value per share

Amount Registered | shares

951,436

Proposed Maximum Offering Price per Unit

1.765

Maximum Aggregate Offering Price

$ 1,679,284.54

Fee Rate

0.01381%

Amount of Registration Fee

$ 231.91

Offering Note

(1) Pursuant to Rule 416(a) under the Securities Act of 1933, as amended (the "Securities Act"), this registration statement shall also cover any additional shares of the Registrant's common stock that become issuable under the Caribou Biosciences, Inc. 2021 Equity Incentive Plan ("2021 EIP") and the Caribou Biosciences, Inc. 2021 Employee Stock Purchase Plan ("2021 ESPP") by reason of any stock dividend, stock split, recapitalization or similar transaction effected without the Registrant's receipt of consideration which would increase the number of outstanding shares of common stock. Additionally, pursuant to Rule 416(b) under the Securities Act, if prior to the completion of the distribution of the securities registered under this registration statement, all the securities of a class, which includes the registered securities, are combined by a reverse stock split into a lesser number of securities of the same class, the number of undistributed securities of such class deemed covered by this registration statement shall be proportionately reduced. (2) Represents additional shares of Common Stock reserved for issuance under the Registrant's 2021 ESPP. (3) Estimated in accordance with Rules 457(c) and 457(h) under the Securities Act solely for the purpose of calculating the registration fee on the basis of $1.765 per share, which is the average of the high and low prices of the Registrant's common stock, as reported on the Nasdaq Global Select Market, on March 3, 2026.