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ChemicalTool NMR
Experimental library · AI prediction

1H NMR Prediction Online

Free online 1H NMR predictor and NMR prediction tool. Draw a structure or enter SMILES to predict proton NMR chemical shifts, or search experimental spectra.

Open the interactive predictor: also see 13C NMR prediction. Browse the compound catalog.

Start prediction Spectrum search

What is NMR prediction?

NMR prediction estimates chemical shifts (and often multiplicities) for a molecule from its structure, so you can compare a proposed structure with measured spectra before running an experiment—or assign peaks when experimental data are available.

How ¹H NMR prediction works on ChemicalTool

You provide a structure—by SMILES, name lookup, or the embedded sketcher—and the service builds a molecular graph, identifies unique proton environments, and applies machine-learned or rule-based models trained on experimental chemical shift data. The output is a table of predicted δ values (ppm) you can export or compare side-by-side with measured peaks when experimental spectra are available in the catalog.

Prediction is fastest when stereochemistry is explicit in the input SMILES. Tautomers, salts, and mixtures may need the dominant species drawn separately. For ¹H work, pick the same deuterated solvent you will use in the lab so predicted values sit closer to reality.

Limitations and good practice

Models extrapolate from training data: unusual heterocycles, heavy halogenation, or paramagnetic contaminants can disagree with experiment. Exchangeable protons (OH, NH) are often broad and solvent-sensitive—¹H predictors may not reproduce lab linewidths. Use prediction to narrow structures, then confirm with a measured spectrum, including solvent residual checks from our residual peak table.

This page does not replace instrument calibration, pulse programs, or 2D experiments. It complements them—especially when you need a quick sanity check before submitting a sample or interpreting a literature structure.

How to use this calculator

  1. Click Start prediction to open the interactive tool with ¹H mode selected.
  2. Enter SMILES or draw the structure; choose solvent if the UI offers it.
  3. Review predicted shifts and multiplicities (¹H).
  4. Search the compound catalog for experimental spectra when available.
  5. Cross-check solvent peaks using CDCl₃ or DMSO-d₆ impurity tables.

For quick reference without a structure, browse the ¹H chemical shift table by functional group.

FAQ

What does an online ¹H NMR predictor do?

It estimates proton chemical shifts and splitting patterns from a molecular structure (SMILES or drawn structure) so you can compare a proposed structure with a measured spectrum or plan an experiment.

How accurate is NMR prediction?

Shift predictions are useful for assignment and teaching, but they depend on the underlying model, solvent, and conformation. Always treat predicted values as guides—not substitutes for experimental spectra on your instrument.

Which solvent should I choose?

Select the deuterated solvent you plan to use (for example CDCl₃ or DMSO-d₆). Residual solvent and water peaks differ by solvent; see the Gottlieb / Fulmer impurity tables on this site.

Can I search experimental spectra here too?

Yes. ChemicalTool NMR combines AI prediction with a local experimental library when data exist for a compound—open the main search or compound pages after predicting.

Is the predictor free?

Basic prediction and reference tables are free to use. Some advanced features may require sign-in depending on site policy.

How is this different from paper tables?

Functional-group shift tables give ranges; a predictor returns compound-specific shifts from connectivity and stereochemistry, which helps when multiple isomers are possible.

References & data sources