Angiotensin II is an important octapeptide hormone—consisting of eight amino acids with the chemical sequence Asp-Arg-Val-Tyr-Ile-His-Pro-Phe—that plays a critical role in the renin-angiotensin system by regulating blood pressure and fluid balance. Its calculated chemical molecular weight is approximately 1,046.18 grams per mole. This precise biochemical weight is vital for pharmacological research, mass spectrometry analysis, and understanding its binding affinity to specific G-protein coupled receptors in cardiovascular medicine.