Plotly Graph
Enter molecule and route descriptors to generate a contribution profile. The default chart shows score interpretation bands.
Calculator Inputs
Example Data Table
| Profile | Atoms | Stereocenters | Macrocycles | Steps | Average Yield | Estimated SA Score |
|---|---|---|---|---|---|---|
| Simple aromatic intermediate | 18 | 0 | 0 | 3 | 85% | 2.90 |
| Lead optimization scaffold | 27 | 2 | 0 | 5 | 76% | 5.25 |
| Macrocyclic stereorich target | 38 | 5 | 1 | 9 | 58% | 8.10 |
These rows are illustrative examples for planning and benchmarking within medicinal or synthetic chemistry workflows.
Formula Used
Estimated SA Score = Clamp( Base + Structural Penalties + Route Penalties - Ease Bonuses, 1, 10 )
Structural penalties include size, heteroatom load, ring burden, stereocenters, spiro atoms, bridgeheads, macrocycles, and flexibility.
Route penalties include rare fragments, protecting group operations, step count, and low average yield.
Ease bonuses include common fragment familiarity, accessible starting materials, molecular symmetry, and route convergence.
This page is a descriptor-based estimator for rapid screening. It is useful for ranking ideas early, but it is not a replacement for full structure-based cheminformatics or retrosynthesis software.
How to Use This Calculator
- Enter the molecule name for reporting and exports.
- Estimate atom count, heteroatom ratio, rings, stereocenters, and other structural descriptors.
- Set route-facing inputs such as step count, average yield, protecting groups, and convergence.
- Click the calculate button to view the score above the form.
- Use the Plotly chart to see which features drive the estimate.
- Download the result as CSV or PDF for documentation.
Frequently Asked Questions
1) What does the synthetic accessibility score mean?
It estimates how easy or difficult a molecule may be to synthesize. Lower values suggest easier synthesis. Higher values imply greater structural complexity, route burden, or lower practicality.
2) Is this an exact cheminformatics SA score?
No. This page uses a descriptor-based estimation model. It is designed for planning, screening, and comparison when exact structure-driven scoring tools are unavailable.
3) What score range is considered easy?
Scores near 1 to 3 are usually interpreted as easier targets. Around 3 to 5 is moderate. Above 5 becomes progressively more challenging.
4) Why do stereocenters increase difficulty?
More stereocenters often require tighter control, specialized reagents, chiral strategies, or extra purification. That tends to increase route complexity and risk.
5) Why do macrocycles and bridgeheads matter?
These motifs often indicate topological strain, restricted geometry, or limited route flexibility. They can demand more optimization and reduce synthetic convenience.
6) How should I choose the common fragment score?
Use higher values when the scaffold relies on familiar, commercially common, or literature-rich fragments. Use lower values when fragments appear unusual or difficult to source.
7) Can I compare two candidate molecules with this page?
Yes. Enter each molecule separately, record the score, and compare both the final value and the contribution chart. That helps identify the main synthetic tradeoffs.
8) Should I use this score alone for project decisions?
No. Combine it with potency, selectivity, safety, solubility, IP constraints, route novelty, and actual laboratory experience before prioritizing a program.