How to Use the Complement Strand Generator
Step 1: Enter your DNA sequence in the 5' to 3' direction in the input box above.
Step 2: Click Generate Complement. The tool shows the original strand and its complement strand directly below.
Step 3: The base pairing visualization shows each base pair aligned vertically ā original on top, complement below, with bond indicators in the middle.
Step 4: Note that this tool gives the complement reading 3' to 5' ā NOT the reverse complement. For reverse complement use the dedicated tool.
Complement vs Reverse Complement
These two terms are often confused. Understanding the difference is essential in molecular biology.
A pairs with T (2 hydrogen bonds)
T pairs with A (2 hydrogen bonds)
G pairs with C (3 hydrogen bonds)
C pairs with G (3 hydrogen bonds)
// Example: ATGCTA
Original 5'ā3': A T G C T A
Complement 3'ā5': T A C G A T ā this tool
Rev Comp 5'ā3': A T C G T A ā reverse complement tool
When Do You Need Just the Complement?
You need the simple complement when writing out a double stranded DNA molecule, studying base pairing rules, or visualizing how two strands align antiparallel to each other. The complement always reads in the opposite direction to the original.
Difference from Reverse Complement
The complement strand reads 3' to 5' ā the opposite direction to the original. The reverse complement is the same sequence but written 5' to 3' by reversing it. For PCR primer design you need the reverse complement, not just the complement.