Free chemistry tools and calculators

Convert SMILES strings to 2D structures and export image files.

Draw a molecule in the 2D editor and copy the realtime SMILES output.

Draw reaction schemes online with reactants, products, arrows, reagents, conditions, and editable examples.

Resolve compound names to a structure image, SMILES, formula, molecular weight, and PubChem CID.

Search PubChem by formula and compare candidate structures, names, CIDs, and SMILES.

Render molecules in 3D and download common chemistry and model formats.

Paste or upload XYZ and Gaussian coordinate files, infer bonds, and export a 2D structure image.

Paste or upload an XYZ coordinate file, infer likely bonds, review the editable structure, and copy best-effort SMILES.

Load proteins by PDB ID or file using 3Dmol.js with style and export controls.

Convert MOL/SDF structure blocks to SMILES in a dedicated converter page.

Convert a SMILES string to downloadable PDB for protein/model pipelines.

Generate docking-friendly PDBQT text from SMILES for AutoDock-style workflows.

Convert PDB structures into PDBQT format in a dedicated browser tool page.

Generate standard InChI identifiers from SMILES strings.

Convert SMILES to compact InChIKey format for indexing.

Convert InChI strings from literature and databases to SMILES.

Resolve InChIKey identifiers to canonical SMILES via API.

Convert SMILES strings into MOL files for compatibility workflows.

Generate SDF output from SMILES for datasets and screening.

Convert ligand PDB blocks to SMILES in a best-effort workflow.

Convert chemical names to SMILES for structure workflows.

Convert SMILES strings into IUPAC names for reporting.

Convert MOL2 ligand blocks to SMILES format.

Resolve PubChem CID values to canonical SMILES identifiers.

Resolve CAS Registry Numbers to SMILES, IUPAC name, formula, molecular weight, and CID.

Look up a CAS number and view the matching 2D chemical structure with metadata.

Convert SMILES into MOL2 format for docking and med-chem workflows.

Convert SDF or MOL blocks into standard InChI identifiers.

Convert SDF or MOL blocks into compact InChIKey strings.

Generate compact InChIKeys from full InChI strings.

Resolve InChIKey values to full InChI via public chemistry endpoints.

Convert MOL or SDF structure blocks to standard InChI.

Convert MOL or SDF blocks to compact InChIKey identifiers.

Calculate exact solute amount needed for target molarity and solution volume.

Use C1V1=C2V2 workflow for quick dilution planning in dedicated page format.

Compute molarity from mass, molecular weight, and final volume.

Find the limiting reactant, excess reagent, leftover amounts, and theoretical yield.

Convert grams to moles or moles to grams using molar mass from a chemical formula.

Calculate percent yield, actual yield, or theoretical yield with common unit support.

Calculate molar mass, element breakdown, and percent composition from a formula.

Calculate molar mass with step-by-step working and convert grams to moles.

Turn percent composition into the empirical and molecular formula, with steps.

Sequence to average/monoisotopic MW in kDa, plus extinction coefficient at 280 nm.

Draw a molecule in the editor and get its IUPAC name instantly.

Complete and net ionic equations with spectator ions from solubility rules.

Full and noble-gas configurations for any element or ion, including Cr and Cu exceptions.

Oxidation states of every element in a compound or ion, with step-by-step rules.

Convert a SMILES string to formula with molecular weight and PubChem metadata.

Calculate molecular weight from SMILES and show formula and compound metadata.

Calculate monoisotopic exact mass from a chemical formula for MS workflows.

Predict isotope pattern peaks, monoisotopic mass, average mass, and molecular ion region.

Open JCAMP-DX, CSV or Bruker NMR files in your browser. Zoom, pick peaks, integrate and find solvent impurities.

Open JCAMP-DX, CSV or SPC IR spectra in your browser. %T or absorbance, baseline, peaks and functional groups.

Open JCAMP-DX or CSV UV-Vis spectra in your browser. λmax, Beer-Lambert, colour, overlays and Tauc band gap.

Open JCAMP-DX, CSV or SPC Raman spectra in your browser. nm to shift, baseline, spikes, smoothing, peaks and bands.

Open JCAMP-DX, CSV, mzML or mzXML mass spectra in your browser. Isotope pattern overlay, adducts, ppm error and neutral losses.

Open CV files from CSV, CH Instruments, BioLogic, Gamry or Autolab. E1/2, ΔEp, ipa/ipc, reference conversion, HOMO/LUMO and Randles-Sevcik.

Open VAMAS, CasaXPS or CSV XPS spectra. Charge correction, Shirley background, peak fitting with doublets, atomic % and survey element ID.

Open TGA and DSC data from CSV, TA Instruments, NETZSCH or METTLER. DTG, step onset and mass loss, Tg, melting and crystallisation with ΔH, and % crystallinity.

Predict 1H and 13C NMR chemical shifts from a SMILES string. This is a prediction, not an experimental spectrum.

Draw a structure and predict 1H and 13C NMR chemical shifts. The table is a model prediction, not a measured spectrum.

Check Rule of Five properties from SMILES or compound name: MW, LogP, HBD, and HBA.

Calculate a simple Lipinski plus Veber-style druglikeness guideline score.

Retrieve PubChem XLogP from SMILES or compound name for hydrophobicity checks.

Calculate topological polar surface area from SMILES or compound name.

Calculate pH, pOH, concentrations, strong acid/base pH, buffer pH, and pKa.

Calculate pKa from pH, pH from pKa, or Henderson-Hasselbalch buffer ratios.

Generate Lewis dot structures from formula and charge with SVG download.

VSEPR chart and shape finder: AXE class, bond angles, hybridization, polarity and a 3D model with lone pairs.

Estimate your 1–5 AP Chem score from MCQ and FRQ points, with cutoffs and what you need for the next score.

Radioactive decay and first-order kinetics: solve N, N₀, t or t½, with decay constant and chart.

Solve PV = nRT for P, V, n or T with unit conversions, plus combined, Boyle, Charles and Gay-Lussac laws.

Balance a reaction, find the limiting reagent and calculate theoretical yield in grams, plus percent yield.

Convert grams, moles, particles, gas litres or solution volume of one species into any other in a reaction, step by step.

Search any molecule and rotate a ball-and-stick, space-filling or wireframe 3D model with CPK colours.

Virtual molecular model kit: snap atoms together with valence checks, live formula, name and 3D, plus 20 challenges.

How to read mass, IR and ¹H/¹³C NMR spectra: annotated spectra, worked examples and practice quizzes.

Editor add-ons with illustrated guides: NMR Analyser, ChEMBL, MEP surfaces, Compare molecules, Protein viewer, Smart Draw, AI spectroscopy, themes.

Interactive ball-and-stick and space-filling models of common molecules with shapes, bond angles, polarity and facts.

Index of hydrogen deficiency from any formula (N, O, halogens, ions) or SMILES, with rings vs π bonds and steps.

Interactive IR correlation table: look up a peak in cm⁻¹ and filter by functional group, with intensity and shape.

Find formulas from an HRMS accurate mass (ppm, adducts, nitrogen rule, RDBE) or CHN elemental analysis.

What SMILES is, every rule with examples, SMILES codes for common molecules and a live validator.

Compute molality from solute amount and solvent mass.