Solubility Prediction Tool

Calculator Inputs

Compound Name

Molecular Weight

logP

Melting Point (°C)

pKa

Compound Type

Temperature (°C)

Target pH

Hydrogen Bond Donors

Hydrogen Bond Acceptors

Rotatable Bonds

Crystal Packing Factor

Salt / Cosolvent logS Shift

Manual Adjustment

Example Data Table

Compound	MW	logP	MP °C	pKa	Type	Temp °C	Predicted mg/L
Sample Compound A	320	2.4	145	7.8	Base	25	2088.14
Weak Acid B	280	1.6	112	4.5	Acid	30	7634.92
Neutral Lead C	410	3.1	198	7.0	Neutral	25	18.56

Formula Used

This tool uses a screening model that estimates intrinsic aqueous solubility from lipophilicity, crystal strength, molecular size, hydrogen bonding, and molecular flexibility.

Intrinsic logS = 0.5 − 0.85×logP − 0.01×(Melting Point − 25) − 0.003×(MW − 200) + 0.08×HBD + 0.05×HBA + 0.02×Rotatable Bonds − 0.22×(Crystal Factor − 1)

Final logS = Intrinsic logS + Ionization Boost + Temperature Boost + Salt/Cosolvent Shift + Manual Adjustment

For acids, ionization boost increases when pH exceeds pKa. For bases, ionization boost increases when pKa exceeds pH. Neutral compounds receive only a small centered pH effect.

Temperature boost = 0.012 × (Temperature − 25)

Unit conversion: mol/L = 10^logS, mmol/L = mol/L × 1000, mg/L = mol/L × Molecular Weight × 1000.

This is a practical prediction model for screening and formulation planning. It does not replace measured shake-flask or kinetic solubility data.

How to Use This Calculator

Enter the compound name for clear exports and result labels.
Add molecular weight, logP, and melting point from reliable characterization data.
Choose whether the compound behaves mainly as an acid, base, or neutral molecule.
Enter pKa and the target pH for the intended dissolution or formulation environment.
Include hydrogen bond counts, rotatable bonds, and crystal factor to refine the estimate.
Use the salt or cosolvent shift when formulation additives improve apparent solubility.
Press the submit button to show the result above the form.
Export the displayed prediction to CSV or PDF for reports.

Frequently Asked Questions

1. What does this tool predict?

It estimates aqueous solubility from physicochemical properties. The result helps compare compounds, prioritize formulation work, and screen compounds before experimental solubility testing.

2. Is the result kinetic or thermodynamic solubility?

It is a practical screening estimate, closer to an equilibrium-style expectation. Actual kinetic behavior can differ because of polymorphs, supersaturation, particle size, and media effects.

3. Why does melting point reduce solubility?

Higher melting points usually indicate stronger crystal packing. Stronger crystals require more energy to dissolve, so predicted solubility often drops as melting point rises.

4. How does pKa affect the result?

Ionizable compounds become more soluble when the pH favors their charged form. The calculator adds an ionization boost when pH and pKa increase dissolved species.

5. What is the crystal packing factor?

It is a user-controlled adjustment for solid-state resistance. Values above one represent stronger packing and usually lower solubility. Values near one reflect average behavior.

6. When should I use salt or cosolvent shift?

Use it when formulation changes are expected to alter apparent solubility. This helps model salts, buffers, surfactants, or cosolvents without changing core structural inputs.

7. Can I use this for regulatory submission?

No. It is best for early screening, comparison, and internal decision support. Regulatory work should rely on validated experimental methods and documented laboratory measurements.

8. Why is there a confidence score?

The score shows how dependable the estimate may be from the given inputs. Extreme properties and heavy manual adjustments reduce confidence because prediction uncertainty grows.