What does this mass spectrum predictor calculate?

It estimates the isotope pattern from the molecular formula, including monoisotopic mass, average mass, nominal molecular ion peak, and relative M, M+1, M+2 and higher isotope peaks.

Does this predict EI or MS/MS fragmentation?

No. This first version predicts isotope distribution from elemental composition. Fragmentation depends on instrument conditions and chemistry-specific pathways.

Mass Spectrum Predictor

Import a compound by PubChem name, draw a molecule, paste SMILES, or enter a molecular formula to estimate isotope pattern peaks, monoisotopic mass, average mass, and the molecular ion region.

Quick answer: search PubChem by name or CID, draw a structure, paste SMILES, or type a formula. The isotope pattern updates from the molecular formula.

Draw or Paste Input

Import from PubChem by name or CID

SMILES input

Molecular formula

Ready. Formula prediction is fully client-side; SMILES lookup uses PubChem.

Predicted Spectrum

Spectrum chart appears here.

What This Mass Spectrum Tool Predicts

This tool predicts isotope distribution from elemental composition. It is useful for molecular ion peak checks, M+1/M+2 pattern interpretation, chlorine/bromine isotope patterns, and exact mass teaching.

Monoisotopic mass: mass from the lightest common isotopes.
Average mass: abundance-weighted molecular mass.
Isotope pattern: relative molecular ion peaks from natural isotope abundances.

This is not an EI fragmentation or MS/MS predictor. Fragment ions depend on ionization method, collision energy, instrument settings, and molecule-specific fragmentation pathways.