Not exactly. base structures of Purines average 120 Da and pyrimidines average 80 daltosns. DNA is made up of dNTPs obviously following the Chargaff law [A+T]n = [G+C]n. You can always calculate the approximate mol weight of DNA of any length with an average dNTP mol weight of 487 Da to approximation

dATP 491.2

dCTP 467.2

dGTP 507.2

dTTP 482.2

Exact M.W. of ssRNA (e.g., RNA Transcript): M.W. = (An x 329.2) + (Un x 306.2) + (Cn x 305.2) + (Gn x 345.2) + 159ª

Exact M.W. of ssDNA (e.g., Oligonucleotides): M.W. = (An x 313.2) + (Tn x 304.2) + (Cn x 289.2) + (Gn x 329.2) + 79.0ª An, Tn, Cn, and Gn are the number of each respective nucleotide within the polynucleotide. ªAddition of "79.0" to the M.W. takes into account the 5' monophosphate left by most restriction enzymes. No phosphate is present at the 5' end of strands made by primer extension. Approximate M.W.'s of Nucleic Acids: M.W. of ssRNA = (# nucleotides x 320.5) + 159.0 M.W. of ssDNA = (# nucleotides x 303.7) + 79.0 M.W. of dsDNA = (# nucleotides x 607.4) + 157.9

Refer: https://www.thermofisher.com/in/en/home/references/ambion-tech-support/rna-tools-and-calculators/dna-and-rna-molecular-weights-and-conversions.html?gclid=Cj0KCQjw8uOWBhDXARIsAOxKJ2EK37ykZWkmpTxREoCsax0tTeugdVxh4En2VhgXel8qawfuvGvWF1saAuLGEALw_wcB&ef_id=Cj0KCQjw8uOWBhDXARIsAOxKJ2EK37ykZWkmpTxREoCsax0tTeugdVxh4En2VhgXel8qawfuvGvWF1saAuLGEALw_wcB:G:s&s_kwcid=AL!3652!3!592852924484!!!g!!&cid=bid_sap_rst_r01_co_cp0000_pjt0000_bid00000_0se_gaw_dy_awa_con