Democratic Republic of the Congo is about 39,081 times bigger than British Indian Ocean Territory.

British Indian Ocean Territory is approximately 60 sq km, while Democratic Republic of the Congo is approximately 2,344,858 sq km, making Democratic Republic of the Congo 3,907,997% larger than British Indian Ocean Territory.
Tip: This to-scale comparison of British Indian Ocean Territory vs. Democratic Republic of the Congo uses the Mercator projection, which distorts the size of regions near the poles.
Compare further: Democratic Republic of the Congo vs. British Indian Ocean Territory