DNA and RNA Molecular Weights and Conversions

Nucleotide Molecular Weights

NucleotideMW (g/mol)
Ribonucleotide Triphosphates (Avg. MW = 499.5)
ATP 507.2
CTP 483.2
GTP 523.2
UTP 484.2
Ribonucleotide Monophosphates (Avg. MW = 339.5)
AMP 347.2
CMP 323.2
GMP 363.2
UMP 324.2
Deoxyribonucleotide triphosphates (Avg. MW = 487.0)
dATP 491.2
dCTP 467.2
dGTP 507.2
dTTP 482.2
Deoxyribonucleotide Monophosphates (Avg. MW = 327.0)
dAMP 331.2
dCMP 307.2
dGMP 347.2
dTMP 322.2

Nucleic Acid Molecular Weight Conversions

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
An, Un, Cn, and Gn are the number of each respective nucleotide within the polynucleotide.
M.W. calculated is valid at physiological pH.
ªAddition of "159" to the M.W. takes into account the M.W. of a 5' triphosphate.

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

ssRNA Size and Mass Conversions

Size (nt) Daltons or g/mol       1 µg equivalent
pmol molecules
20 6,569 152.23 9.17 x 1013
100 32,209 31.05 1.87 x 1013
300 96,309 10.38 6.25 x 1012
500 160,409 6.23 3.75 x 1012
1000 320,659 3.12 1.88 x 1012
1800 577,059 1.73 1.04 x 1012

ssDNA Size and Mass Conversions

Size (nt) Daltons or g/mol       1 µg equivalent
pmol molecules
20 6,153 162.52 9.79 x 1013
100 30,449 32.84 1.98 x 1013
300 91,189 10.97 6.6 x 1012
500 151,929 6.58 3.96 x 1012
1000 303,779 3.29 1.98 x 1012
1800 546,739 1.83 1.1 x 1012

dsDNA Size and Mass Conversions

Size (nt) Daltons or g/mol       1 µg equivalent
pmol molecules
20 12,306 81.26 4.89 x 1013
100 60,898 16.42 9.89 x 1012
300 182,378 5.48 3.3 x 1012
500 303,858 3.29 1.98 x 1012
1000 607,558 1.65 9.91 x 1011
1800 1,093,478 0.91 5.51 x 1011

Absorbance Units to Nucleic Acid Concentration Conversion

1 A260 dsDNA = 50 µg/ml

1 A260 ssDNA = 37 µg/ml

1 A260 ssRNA = 40 µg/ml








Nucleotide Absorbance Maxima and Molar Extinction Coefficients

NucleotideAbsorbance
Maximum at pH 7.0 (nm)		Molar Extinction
Coefficient at pH 7.0
ATP 259 15,400
CTP 271 9,000
GTP 253 13,700
UTP 262 10,000
dATP 259 15,200
dCTP 271 9,300
dGTP 253 13,700
dTTP 267 9,600
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