This program will take a nucleic acid sequence and calculate the molecular weight and GC content. The program will ignore numbers, spaces or characters like B or Z which do not correspond to one of the 5 DNA bases. It was actually quite interesting to research how to make this program. The atomic weights for each atom used are from the International Union of Pure and Applied Chemistry (IUPAC) web site here. This data gives average atomic weights based on average isotopic content on the planet earth, which can of course vary somewhat. The values, in Daltons, are H=1.00794, C=12.0107, N=14.0067, O=15.9994 and P=30.973761. These figures should give you far greater accuracy than you are likely to need, and the program actually rounds to the nearest hundredth of a Dalton. The program assumes that each phosphate group has two hydrogen atoms bound to it, which may not be true outside the physiological pH range. This version can also deal with FASTA format sequences (see here for info on that); it ignores any line of text which is started by a ">" character. The program can also process multiple FASTA format entries, only counting the sequence data and ignoring the stuff following the ">".
Please type or paste your DNA sequence in box below, can be upper or lowercase, program will read either and both.