Protein sample evaluation is an important step in many protein workflows. The NanoDrop One microvolume spectrophotometer supports protein sample quantification with multiple preconfigured applications, including direct absorbance at A280, A205, or other wavelengths using the Thermo Scientific™ Pierce™ colorimetric assays (BCA, Rapid Gold BCA, Pierce 660, Bradford, etc.) and a proteins and labels application for quantitation of metalloproteins and fluorescently labeled proteins. We will review what you need to consider when choosing a protein quantification method for your sample. Is the sample one purified protein or a mixture of proteins? Does your peptide contain tyrosine and tryptophan residues? Does the sample buffer absorb in the UV spectrum? How can co-purified DNA affect your protein sample measurement? What is a good blank/control for your sample? Answers to these questions and other key considerations will be discussed.