Cocos (Keeling) Islands is about 4.3 times smaller than British Indian Ocean Territory.

British Indian Ocean Territory is approximately 60 sq km, while Cocos (Keeling) Islands is approximately 14 sq km, making Cocos (Keeling) Islands 23.33% the size of British Indian Ocean Territory.
Tip: This to-scale comparison of British Indian Ocean Territory vs. Cocos (Keeling) Islands uses the Mercator projection, which distorts the size of regions near the poles.
Compare further: Cocos (Keeling) Islands vs. British Indian Ocean Territory