⚖️ Protein Calculator

Molecular Weight / pI Calculator

Calculates protein molecular weight, isoelectric point (pI), and amino acid composition from amino acid sequences or FASTA format. Lowercase amino acid sequences are also supported, and all input data are processed only within your browser.

📥 Sequence Input
Sequences: 0 Valid Amino Acids: 0 Removed Characters: 0
⚙️ Calculation Settings
Basic Options
Line Width
Mass / pI Options
Mass Type
pKa Set
N-terminus pKa
C-terminus pKa
Molecular weight is calculated by summing the residue masses of each amino acid and adding terminal water H₂O. pI is estimated by binary search from the charges of the N-terminus, C-terminus, and D/E/C/Y/H/K/R side chains.
📊 Calculation Summary
🧩 Amino Acid Composition
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