Fragmento restrição
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
|site2 - site1|
About this calculator
This calculator determines the size of DNA fragments produced by restriction enzyme digestion. By entering numeric positions that represent the sites of two cuts in the genome, it calculates the distance between them, giving the fragment length in base pairs.
The calculation relies on the absolute difference between the site coordinates. The formula is |site2, site1|, where site1 and site2 are the positions of the first and second cut sites, respectively. This method guarantees a positive result regardless of the order in which the sites are entered.
Use this tool when estimating fragments for cloning projects, genomic mapping, or analyzing enzyme cutting patterns. It is valuable in laboratories that need to design vectors, validate sequences, or predict digestion outcomes in molecular biology experiments.
Be careful with overlapping sites, sequence variations that alter enzyme recognition, or cuts occurring at the same location. Also verify that each site’s position is accurate relative to the reference used, as coordinate errors produce incorrect fragment sizes.
Frequently asked questions
What if the restriction enzyme has multiple sites on the same molecule?
Enter the coordinates for each pair of sites you want to evaluate. The calculator will give the fragment size for each interval, letting you compare different cuts.
What happens if the entered sites are identical?
The absolute difference will be zero, indicating no fragment between those points; this could signal a typo or that the sites coincide.
How do I handle mutations that change the recognition sequence?
Update the coordinates based on the altered sequence before using the calculator, since the presence or absence of a site impacts the final fragment size.
Can I use this tool for RNA fragments?
Yes, as long as you have the numeric positions of cuts in RNA, although most restriction enzymes act on DNA.
Does the calculator account for 5’ or 3’ sticky ends?
No, it only calculates the distance between sites. Adjust the fragment size manually if sticky ends affect your experimental design.