Protein Solubility Calculator

Created by Komal Rafay
Reviewed by Purnima Singh, PhD and Steven Wooding
Based on research by
Kramer RM, Shende VR, Motl N, Pace CN, Scholtz JM Toward a Molecular Understanding of Protein Solubility: Increased Negative Surface Charge Correlates with Increased Solubility. Biophys J. 2012 Apr 18; 102(8): 1907–1915 (18 April 2012)See 1 more source
Evers JM, Hughes CG ANALYSIS | Chemical Analysis Encyclopedia of Dairy Sciences, Elsevier, 2002, Pages 34-40 (2002)
Last updated: Oct 03, 2022

Omni's protein solubility calculator is a convenient tool built to determine the protein content in different foods.

The basis of our tool is the Kjeldahl method, and here today, we will be discussing how to calculate the protein solubility and whether these proteins are soluble in water or not. We will also take a look at the factors on which protein solubility depends and a step-by-step view of the protein solubility formula.

So let's just dive into it and explore the world of protein solubility.

How to use the protein solubility calculator

Our protein solubility calculator is a tool based on the Kjeldahl method. The primary purpose of this method is to determine the nitrogen content in different organic and inorganic substances. It also helps estimate the amount of protein present in various food groups. Our protein calculator can help you better understand proteins and their significance in life.

On the other hand, the protein solubility calculator estimates the protein solubility as a percentage.

  1. So, to start, the first thing you input is the blank titer. Blank titration is titration in the absence of an analyte.

  2. Next, input the titer.

  3. Input the normality of NaOH (sodium hydroxide). The default unit used is grams, but you can choose other units based on the information you have.

  4. Lastly, input the effective weight, which is also in grams by default.

  5. Once you input the values, that is when the magic happens, and the tool calculates the protein solubility percentage.

Omni's titration calculator is sure to come in handy. It makes sure you never have to question your titration skills.

Protein solubility factors

The concentration of a protein in saturated solutions at equilibrium is protein solubility, given certain conditions are met. It is a thermodynamic parameter that can be affected by various factors.

Some critical factors that influence protein solubility are:

  • Temperature;
  • pH;
  • Ionic strength; and
  • Solvent additives.

And if you want to enhance your knowledge further, then make sure to check out our ionic strength calculator to understand better the factors that affect protein solubility.

Protein solubility formula

In structural biology, protein solubility is of great significance. The protein solubility formula determines the percentage of the soluble protein.

P=1.401×6.25×5×(bt)×nm\footnotesize P = 1.401 \times 6.25 \times 5 \times (b- t) \times \frac{n}{m}


  • PP – Protein percentage;
  • bb – Blank titer;
  • tt – Titer;
  • nn – Normality of NaOH; and
  • mm – Effective weight.

How to calculate the protein solubility?

The protein solubility formula uses many variables to determine the solubility percentage, making it look scary at first glance, but it couldn't be any easier. Once we take each step individually, we'll laugh at judging the formula too soon.

  1. First, subtract the amount of titer from the blank titer.
  2. Then divide the normality of NaOH by the effective weight.
  3. Now, calculate the product of 1.401, 6.25, and 5.
  4. Lastly, multiply the results of steps 1, 2, and 3.
  5. The result is the protein solubility as a percentage.

So, for instance, you were to determine the protein solubility percentage of a substance with the given characteristics.

  • Blank titer = 7;
  • Titer = 6;
  • Normality of NaOH = 98 g; and
  • Effective weight = 55 g.

The equation becomes:

P=1.401×6.25×5×(76)×9855=1.401×6.25×5×1×1.7818=78.01%\footnotesize \begin{split} P &= 1.401 \times 6.25 \times 5 \times (7-6) \times \frac{98}{55}\\[1em] &= 1.401 \times 6.25 \times 5 \times 1 \times 1.7818\\[.5em] &= 78.01\% \end{split}


Are proteins soluble in water?

Yes, proteins are soluble in water, but not all of them. There are two categories of proteins, water-soluble and insoluble.

The 3D shape of a protein determines its solubility in water.

The proteins with a globular structure are soluble in water, whereas the fibrous proteins are insoluble.

Why is solubility of protein important?

The high solubility of proteins determines their suitability for use in liquid foods and beverages, and high soluble proteins can also disperse protein molecules or particles into fine particles.

In some instances, the solubility of a protein can be increased by using buffers.

How can I calculate the protein solubility percentage?

The formula to calculate the protein solubility percentage is:

P = 1.401 × 6.25 × 5 × (b - t) × n / m,


  • P – Protein percentage;
  • b – Blank titer;
  • t – Titer;
  • n – Normality of NaOH; and
  • m – Effective weight.
  1. So, determine the product of 1.401, 6.25, and 5.
  2. Then multiply the result by the difference between the blank titer and titer.
  3. Lastly, multiply the result by the quotient of normality of NaOH and effective weight.
  4. The result is the protein solubility percentage.

Why is blank titration needed?

The titration done in the absence of an analyte is called blank titration. It helps determine any possible errors in the solution.

For instance, you want to carry out acid-base titration but know that the deionized water might impact the result. In this situation, a blank titration determines the potency of the reactive substance in water and, based on the results, helps correct the concentration for the acid-base titration's analyte.

Komal Rafay
Blank titer (B)
Titer (T)
Normality of NaOH (N)
Effective weight (M)
Protein solubility percentage (P)
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