Bio-Tools

PDB File Converter

Molecular File Converter

Convert between chemical file formats with our web-based tool

Convert Molecular Files

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Supports PDB, SDF, MOL2 and many more

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Authors: Mahdi Morshedi Yekta, Fatemeh Faryadras | Need help? Contact Support

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PDB File Converter

Our PDB File Converter is a powerful web-based utility that reformats 3D molecular structures for broad compatibility across computational chemistry and structural biology applications. This tool efficiently converts the standard Protein Data Bank (PDB) format to a wide range of essential file formats, including MOL2, SDF, and PDBQT. During the conversion process, it preserves all critical atomic coordinate data while optimizing compatibility with different software environments. This transformation is essential for preparing molecular structures for downstream tasks such as molecular docking, molecular dynamics simulations, and advanced visualization, ensuring your data is precisely formatted for seamless integration into any computational workflow.

Input FormatData TypePossible Output Formats
pdb3D Molecular Structureabinit, adf, adf_band, adf_pipe, alc, bgf, box, c3d1, c3d2, caccrt, cache, cacint, c3xml, can, car, castep, ccc, cdx, cdxml, cht, cif, ck, cml, cmlr, com, CONFIG, CONTCAR, contcar, crk2d, crk3d, csr, cssr, ct, cub, cube, dmol, ent, exyz, fa, fasta, fch, fchk, fck, feat, fh, fix, fpt, fract, fs, g03, g09, g16, g92, g94, g98, gam, gamess, gamin, gamout, gau, gjc, gjf, gpr, gr96, gukin, gukout, gzmat, hin, inchi, inchikey, inp, ins, jout, jdx, k, lpmd, mcdl, mcif, mdl, mmd, mmod, mol, mol2, mold, molden, molf, moo, mop, mopcrt, mopinp, mopout, mpc, mpo, mpqc, mrv, msi, msms, nw, nwo, o, out, outmol, pc, pcm, pcm_input, pdb, pdbqt, png, POSCAR, poscar, pov, pqr, pqs, prep, qcin, qcout, report, res, rsmi, rxn, sd, sdf, smi, smilies, sy2, t, t41, tdd, therm, tmol, txt, vasp, VASP, vout, wln, xsd, xtc, xyz, yob

How to use (step-by-step)

Follow these simple steps to convert your file in seconds.

  1. Upload Your File: Click “Upload File” or drag and drop your PDB file directly into the designated area. You can also paste the file’s content using the “Paste Data” option.
  2. Select Your Formats: The input format will be automatically detected as PDB. Use the “Output Format” dropdown menu to select your desired format, such as mol2, sdf, or pdbqt.
  3. Start the Conversion: Press the “Convert File” button to begin the process. The tool will process your file instantly.
  4. Download Your File: Once the conversion is complete, a download link for your new file will appear. Click it to save the file to your device.

Tip: If you see an error during conversion, check the Troubleshooting Guide below—common causes and fixes are listed.

Conversion Process

Converting your PDB file involves a complete syntactical transformation. Here’s a breakdown of the input format, the common output formats you can choose, and the core changes that happen during the conversion.

The Input: PDB Format

The PDB (Protein Data Bank) format is a standard textual file format for describing the three-dimensional structures of molecules held in the Protein Data Bank. It is a fixed-column format, meaning that specific information (atom number, atom name, residue name, coordinates, etc.) must appear in designated columns on each line.

Example PDB file:

HEADER    HYDROLASE (ACID PROTEINASE)         24-SEP-98   1A5M
ATOM      1  N   ASP A   1      20.692  32.115  31.996  1.00 11.96           N
ATOM      2  CA  ASP A   1      21.129  31.292  30.824  1.00 12.01           C
ATOM      3  C   ASP A   1      22.650  31.258  30.822  1.00 11.43           C
ATOM      4  O   ASP A   1      23.220  32.100  31.470  1.00 12.15           O
ATOM      5  CB  ASP A   1      20.428  31.642  29.510  1.00 12.63           C
ATOM      6  CG  ASP A   1      20.890  30.850  28.318  1.00 14.12           C
ATOM      7  OD1 ASP A   1      21.989  30.328  28.435  1.00 14.28           O
ATOM      8  OD2 ASP A   1      20.147  30.772  27.359  1.00 15.11           O

Common Output Formats & Their Uses

Your choice of output format depends on the software or analysis you plan to use next.

  • mol2 Format: A multi-purpose format developed by Tripos that includes 3D coordinates, atom types, and partial charges. It is highly structured and widely supported.
    • Best for: Preparing structures for molecular docking with programs like DOCK and GOLD, and for use in molecular modeling software like UCSF Chimera or PyMOL.
  • sdf Format: The structure-data file format can contain one or more molecules, along with associated data for each. It is excellent for representing small molecule libraries.
    • Best for: Storing chemical libraries, exchanging data between cheminformatics tools, and preparing inputs for virtual screening software.
  • pdbqt Format: A specialized format used by AutoDock software. It is an extension of the PDB format, adding information about partial charges and AutoDock atom types.
    • Best for: Preparing both ligand and receptor files specifically for molecular docking simulations using AutoDock Vina and related tools.
  • xyz Format: A very simple format that lists the element symbol and Cartesian coordinates (X, Y, Z) for each atom. It does not contain connectivity information.
    • Best for: Quick visualization, geometry optimization inputs for quantum chemistry software, and trajectory analysis.

The Core Transformation Process

Regardless of the output you select, the converter performs these fundamental steps:

  1. Parses Atomic Coordinates: It reads the ATOM and HETATM records from the PDB file to extract the element type and its X, Y, and Z coordinates.
  2. Infers Connectivity and Bond Orders: It determines which atoms are bonded to each other based on distance criteria.
  3. Applies New Formatting Rules: It rebuilds the file according to the syntax of your chosen output format—whether that means creating TRIPOS blocks for mol2, adding charge and atom type information for pdbqt, or simply listing coordinates for xyz.

Compatible Software

The generated output files can be used with hundreds of molecular modeling tools. The ideal software depends on your chosen format:

  • mol2 files: UCSF Chimera, PyMOL, Discovery Studio, MOE, DOCK, GOLD.
  • sdf files: ChemDraw, DataWarrior, KNIME, and most cheminformatics platforms.
  • pdbqt files: AutoDock Vina, AutoDock Tools (ADT), PyRx.
  • xyz files: Avogadro, VMD, GaussView, and most quantum chemistry packages.

Troubleshooting Guide

Encountering an error can be frustrating, but most issues are easy to fix. Here are the most common problems you might face and how to resolve them.

General Tool Errors

Error: “File size exceeds the limit”

  • Why it happens: Your uploaded file is larger than the maximum allowed size. Our server has this limit to ensure quick processing for all users.
  • How to fix: If your PDB file is exceptionally large, try removing unnecessary elements like solvent molecules or selecting only a specific chain of interest. For processing larger files or to inquire about unlimited usage, please contact us for custom solutions.

Error: “Processing timed out”

  • Why it happens: The conversion for your molecule is taking too long, which can happen with extremely large or complex structures.
  • How to fix: Try to simplify your input file. If the issue persists because your structure is inherently complex, please contact us to discuss options for handling larger computations.

Error: “CAPTCHA validation failed”

  • Why it happens: Our system uses a CAPTCHA to prevent automated bots. This error occurs if the CAPTCHA was not solved correctly or timed out.
  • How to fix: Simply reload the page and solve the new CAPTCHA. If you continue to have trouble after reloading, please get in touch with our support team.

Conversion-Specific Errors

These errors typically relate to the scientific data within your PDB file.

Error: “Missing atoms or residues”

  • Why it happens: Your input PDB file is structurally incomplete, with missing atoms in the side chains or gaps in the protein backbone, which is common in experimentally determined structures.
  • How to fix: Before converting, you should repair the structure using modeling software (like PyMOL or UCSF Chimera) to add the missing atoms or residues.

Error: “Unrecognized residue or atom name”

  • Why it happens: The PDB file contains non-standard residue or atom names (e.g., from a modified amino acid or an uncommon ligand) that the tool does not recognize.
  • How to fix: Ensure all residue and atom names conform to the standard PDB format. You may need to manually edit the PDB file to correct these names to standard equivalents.

Error: “Failed to add hydrogens” or “Could not perceive bond orders”

  • Why it happens: This often indicates a problem with the molecule’s geometry, such as distorted bond lengths or unusual angles, which prevents the software from correctly inferring chemical structures.
  • How to fix: It’s recommended to perform an energy minimization on your structure using software like GROMACS, AMBER, or UCSF Chimera to relax the structure into a more chemically reasonable conformation.

If your problem isn’t listed here, we want to know about it! Please help us improve the tool by reporting the issue.

Support Our Work

We are committed to keeping our scientific tools free and accessible for everyone. If this tool has supported your research or made your work easier, please consider contributing to our mission with a donation. Your support directly helps us cover server costs and fund the continued development of new, powerful tools for the global scientific community.

References & Suggested Reading

This tool was developed in line with established principles in computational chemistry for accurate, reliable results. The resources listed below are the foundational research and key papers that define these standards, and we highly recommend them for a deeper understanding of the scientific principles.

Dalby, A., Nourse, J. G., Hounshell, W. D., Gushurst, A. K. I., Grier, D. L., Leland, B. A., & Laufer, J. (1992). Description of several chemical structure file formats used by computer programs developed at Molecular Design Limited. Journal of Chemical Information and Computer Sciences, 32(3), 244-255. https://doi.org/10.1021/ci00007a012

Berman, H. M., Westbrook, J., Feng, Z., Gilliland, G., Bhat, T. N., Weissig, H., Shindyalov, I. N., & Bourne, P. E. (2000). The Protein Data Bank. Nucleic Acids Research, 28(1), 235–242. https://doi.org/10.1093/nar/28.1.235

Eberhardt, J., Santos-Martins, D., Tillack, A. F., & Forli, S. (2021). AutoDock Vina 1.2.0: New docking and screening features. Journal of Chemical Information and Modeling, 61(8), 3891–3898. https://doi.org/10.1021/acs.jcim.1c00203

O’Boyle, N. M., Banck, M., James, C. A., Morley, C., Vandermeersch, T., & Hutchison, G. R. (2011). Open Babel: An open chemical toolbox. Journal of Cheminformatics, 3(1), 33. https://doi.org/10.1186/1758-2946-3-33

Meet the Authors

Mahdi Morshedi Yekta

Mahdi Morshedi Yekta

Founder & Bioinformatics Developer

Mahdi is the founder of ScienceCodons and a Medical Biotechnologist with a deep passion for computational biology. Holding an M.Sc. in Medical Biotechnology, he specializes in transforming complex biological algorithms into accessible, high-performance web tools, bridging the gap between laboratory sciences and software engineering.

Fatemeh Faryadras

Fatemeh Faryadras

Medical Biotechnologist & Researcher

Fatemeh is a Medical Biotechnologist and researcher. With extensive expertise in genetic engineering, molecular cloning, and cancer biology, she combines her rigorous laboratory background with intuitive design principles to create reliable, user-centered scientific calculators and tools.

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