N50 value is equal to the single contig?

Question

[ve9]

I have some assemblies of ONT reads with Flye and/or Unicycler where after Quast N50 seems to be same as the length of the single circular contig of the bacteria I recover? Is that normal?

Answer 1

[WouterDeCoster]

N50 is a measure of how contiguous your assembly is, as in the past, without long read sequencing, assembly commonly resulted in incomplete chromosomes and separate contigs.

So in a perfect assembly for a single chromosome you would indeed expect that N50 == chromosome length.

See this blog post series for further reading about how N50 is calculated.