**7. Concluding Remarks and Recommendations**

Cytometric methods suitable for the estimation of nuclear genome size independent of DNA sequence data require a reference standard of known genome size. The most widely used animal and plant DNA reference standards have been calibrated from the human male leucocyte genome, assuming its length to be 3.42 Gbp/1C (and its 2C content to be 7 pg DNA), even though the length estimate is 5.1% greater than what the most current assembly predicts; however, given that the GRCh38.p12 assembly is most probably still incomplete, the real difference may be smaller than this. Thus, for the moment, it would seem reasonable to continue with this figure. The use of an agreed standard will facilitate comparisons between results obtained in different laboratories. Once the human genome size is known to a yet higher level of precision, it will be straightforward to recalculate the size of genomes estimated to date.
