URI Genomics & Sequencing Center
Calculator for determining the number
of copies of a template

enter amount of DNA (ng):

enter length of template (bp):

number of copies :x10^

This calculation is based on the assumption that the average weight of a base pair (bp) is 650 Daltons.   This means that one mole of a bp weighs 650 g and that the molecular weight of any double stranded DNA template can be estimated by taking the product of  its length (in  bp) and 650.

The inverse of the molecular  weight is the number of moles of template present in one gram of material.

Using Avogadro's number, 6.022x1023 molecules/mole, the number of molecules of the template per gram can be calculated:

mol/g * molecules/mol = molecules/ g

Finally, the number of  molecules  or number of copies of template in the sample can be estimated by multiplying by 1*109 to convert to ng and then multiplying by the amount of template (in ng)

This calculator requires the user to input the amount of a template present (in ngs) and the length of the template (in bp) and with this information the number of copies of the template is calculated.
The formula used is:
number of copies = ( amount * 6.022x1023) / (length * 1x109 * 650)

number = (ng * number/mole) / (bp * ng/g * g/ mole of  bp)
Created by Andrew Staroscik
29 January 2004