Understand the relationship
The reasoning behind the result
Complement and reverse complement differ
reverse complement = reverse(complement(sequence))
A same-order complement aligns paired bases under the entered 5′→3′ string and is therefore interpreted antiparallel. Reversing it writes the partner in the usual 5′→3′ direction.
These two outputs are both displayed so orientation is inspectable.
DNA and RNA use different partners for A
DNA maps A to T, whereas RNA maps A to U. C and G remain paired in both polymers.
A sequence containing the other polymer's exclusive symbol is rejected rather than silently converted.
IUPAC ambiguity is complemented as a set
R means A or G and complements to Y, meaning C or T/U. Self-complementary sets such as S and W remain themselves.
No base is selected from an ambiguity code.
Pairing syntax is not structure prediction
The transform does not calculate duplex stability, secondary structure, strand abundance, genomic locus or hybridization specificity.
Modified bases and nonstandard pairing require a different chemical representation.
Follow the numbers
Build a DNA reverse complement
- The entered DNA is 5′-ATGCRYTTAA-3′.
- The same-order paired symbols are TACGYRAATT.
- R complements to Y and Y complements to R because their possible-base sets swap.
- Reversing the paired string gives TTAARYGCAT.
- The reported reverse complement is 5′-TTAARYGCAT-3′.
The output preserves sequence uncertainty and direction; it does not predict binding or function.
Quick guide
How to use this calculator
- Choose DNA or RNA so thymine and uracil are never mixed silently.
- Use same-order complement to inspect paired columns and reverse complement for a partner strand written 5′→3′.
- Retain the direction labels when copying a result into another workflow.
Calculation method
Calculation and interpretation
Keep base pairing separate from orientation reversal and make the requested polymer explicit.
Complement each IUPAC symbol by its paired base set; reverse-complement mode then reverses that complemented string so the result is written 5′→3′.
Worked example
Build a DNA reverse complement
The output preserves sequence uncertainty and direction; it does not predict binding or function.
Complement each IUPAC symbol by its paired base set; reverse-complement mode then reverses that complemented string so the result is written 5′→3′.
Supported inputs
Precision and limits
One declared polymer
DNA accepts T and RNA accepts U; mixed T/U input is rejected.
One continuous record
One raw or single-record FASTA sequence is transformed without alignment or assembly.
IUPAC ambiguity only
Every ambiguity code remains a set; modified or nonstandard bases are unsupported.
No structure or specificity
Hybridization, secondary structure, melting and off-target interpretation are excluded.
Numerical support
The complete entered, complement and reverse-complement strings are retained for up to 20,000 symbols.
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