Protein Molecular Weight Calculator
Calculate the molecular weight and properties of proteins from amino acid sequences
Input Sequence
Example: MVLSPADKTNVKAAWGKVGAHAGEYGAEALERMFLSFPTTKTYFPHFDLSH
Additional Properties
Positive Residues (K, R, H)8
Negative Residues (D, E)5
Aliphatic Index61.37
GRAVY-0.204
Molecular Weight
5644.43 Da
5.644 kDa
Length
51 aa
Avg Residue MW
110.7
Extinction Coefficient
8,480 M⁻¹cm⁻¹
at 280 nm (assuming all Cys reduced)
Amino Acid Composition
A
7
14%
G
4
8%
L
4
8%
K
4
8%
F
4
8%
T
4
8%
E
3
6%
H
3
6%
P
3
6%
S
3
6%
V
3
6%
D
2
4%
M
2
4%
Y
2
4%
R
1
2%
N
1
2%
W
1
2%
About Protein Molecular Weight
Protein molecular weight is calculated from the sum of amino acid residue masses minus water lost during peptide bond formation.
The average amino acid residue mass is approximately 110 Da. Key features:
- Extinction Coefficient: Based on Trp, Tyr, and Cys content
- Aliphatic Index: Indicates thermostability
- GRAVY: Grand Average of Hydropathy - positive values indicate hydrophobic proteins
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Editorial Note
MyCalcBuddy Editorial Team
This page is maintained as an educational calculator reference.
📚
Formula Source: Standard Mathematical References
by Various
🔄Last reviewed: May 2026
✓Formula checks are based on standard references and internal QA review.