Collaborative Computational Project
for Electron cryo-Microscopy


MRC/CCP4 file format for images and volumes


We have agreed an update to the MRC/CCP4 format. Details of the changes have been published in Cheng et al. (2015) "MRC2014: Extensions to the MRC format header for electron cryo-microscopy and tomography" J. Struct. Biol. 192, 146-150. See separate page for detailed format specification.


The original MRC/CCP4 format was agreed between the crystallography and EM communities in 1982. An update to this format was agreed in 2000 to include a machine stamp in the file header, to aid file portability. Details of MRC2000 are kept for historical reasons, but please refer to the MRC2014 page for up-to-date information.

Future updates to the format

CCP-EM have undertaken to curate the MRC format on behalf of the EM community. The format is closely linked to the MRC software library, which is distributed by CCP-EM since January 2015 (see Downloads page).

As part of the curation, we will look into possible future updates to the MRC/CCP4 format. The procedure will be:

On-going proposals

Please see separate page.