C20

C20 or C-20 may be:

* C20 (engineering), a mix of concrete that has a compressive strength of 20 newtons per square millimeter
* HMS C20, a 1910 British C class submarine
* Sauber C20, a 2001 racing car
* C-20 is a series designation for military aircraft:
** C-20 would have been the in-service designation of the Fokker F.32
** C-20A/B/C/D/E are variants of the Gulfstream III
** C-20F/G/H/J are variants of the Gulfstream IV
* The OMX Copenhagen 20, also known as the OMXC20, Denmark's primary stock market index
* The Canadian Clarity Act, also known as Bill C-20
* C20 (Airport), Berrien Springs or Andrews University Airpark
*, the smallest possible fullerene
* Malignant neoplasm of rectum ICD-10 code