⭐ Starlight Tools / Molecular Weight Calculator

How This Tool Works

This Molecular Weight Calculator provides a simple and accurate way to determine the molecular mass of various substances, from small chemical compounds to large biological macromolecules like proteins, DNA, and RNA.

Chemical Formula Calculation (e.g., C6H12O6)

For chemical formulas, the tool parses your input, identifies each element and its count, and then sums their respective atomic weights. For example, in $H_2O$, it identifies two Hydrogen atoms and one Oxygen atom, and calculates the total weight based on their atomic masses.

It supports standard elemental symbols (e.g., C, H, O, N, S, P, Fe, etc.) and numerical subscripts. Ensure correct capitalization (e.g., 'Co' for Cobalt vs. 'CO' for Carbon Monoxide).

Biological Sequence Calculation (Proteins, DNA, RNA)

When you input a biological sequence, the tool intelligently attempts to identify whether it's a DNA, RNA, or protein sequence based on the characters present:

• DNA: Sequences containing A, T, C, G (e.g., `ATGCGT`)
• RNA: Sequences containing A, U, C, G (e.g., `AUGCGU`)
• Protein: Sequences containing standard one-letter amino acid codes (e.g., `AGYWCF`). Note that common ambiguous codes are also supported.

For biological polymers, the calculation accounts for the **loss of water** ($H_2O$) during the formation of peptide bonds (proteins) or phosphodiester bonds (nucleic acids). This ensures a highly accurate molecular weight for the intact polymer.

Molecular Weight Data Used

The calculations are based on the average atomic weights of elements and the average molecular weights of amino acid and nucleotide residues (monomers minus water), as widely accepted in scientific literature.

• Atomic Weights: Based on the latest IUPAC recommended atomic weights.
• Amino Acid/Nucleotide Weights: Average weights for standard amino acids and nucleotides.

This tool operates entirely client-side in your browser, ensuring your data remains private and secure.