Methanocalculus is a genus of archaeans in the order Methanomicrobiales, and is known to include methanogens.
The genome of Methanocalculus is somewhat different from other genera of methanogenic archaea, with less than 90% 16S ribosomal RNA similarity. The species within Methanocalculus also have a greater tolerance to salt than other microorganisms, and they can live at salt concentrations as high as 125 g/L. Some species within Methanocalculus are neutrophiles, and Methanocalculus natronophilus, discovered in 2013, is a strict alkaliphile.
The name "Methanocalculus" has Latin roots: "methano" for methane and "calculus" for gravel. Overall, it means gravel-shaped organism that produces methane.
The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN) and National Center for Biotechnology Information (NCBI).