Lipinski 1997 · recomputed in your browser

Rule-of-Five CheckerWill this molecule survive being swallowed?

Type a molecule as SMILES — a line of text that spells out its atoms and bonds. This page parses it here, on your machine, and scores it against the four rough limits Christopher Lipinski pulled out of the drugs that actually made it to market.

Teaching tool

The parser handles a useful subset of SMILES and the logP figure is a simplified atom-contribution estimate — close enough to reason with, not close enough to file with. Nothing here is a substitute for RDKit, a real cheminformatics stack, or a chemist.

Examples

Drug space — where real molecules actually sit

Every dot is a real compound whose SMILES this page parsed on load, using the same code that scored the molecule above. The shaded box is the half of the rule you can draw: weight under 500, logP under 5. Click any dot to load it — or tab into the map and walk it with the arrow keys.

Show the working — how that logP number is built

  1. MW ≤ 500 — molecular weight, summed from the parsed atoms plus implicit hydrogens.
  2. logP ≤ 5 — greasiness. Estimated by adding up per-atom contributions, Crippen-style.
  3. HBD ≤ 5 — hydrogen-bond donors, counted Lipinski's way: every N–H and O–H.
  4. HBA ≤ 10 — hydrogen-bond acceptors, counted Lipinski's way: every N and O atom.