NMR Chemical Shift Calculator

NMR chemical shift prediction estimates where each atom in a molecule will appear on an NMR spectrum — expressed in parts per million (ppm) — without running a physical experiment. Enter your molecule as a SMILES string, then select your solvent, chemical shift reference (TMS, DSS, or TSP), NMR type (¹H or ¹³C), and spectrometer frequency to get predicted chemical shifts (ppm) for each atom. Secondary outputs include the number of signals, chemical shift range, and prediction confidence. Also try the Arterial Blood Gas (ABG) Calculator.

Enter the SMILES notation for your molecule

Results

Predicted Chemical Shifts

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Number of Signals

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Chemical Shift Range

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Prediction Confidence

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Results Table

Frequently Asked Questions

What is an NMR chemical shift predictor?

An NMR chemical shift predictor is a computational tool that uses machine learning or quantum mechanical calculations to predict the chemical shifts of atoms in organic molecules. It helps chemists estimate NMR spectra before running expensive experiments. See also our Calibration Curve Calculator (Analytical).

How accurate are predicted NMR chemical shifts?

Modern prediction methods can achieve accuracy within 0.1-0.5 ppm for ¹H NMR and 1-3 ppm for ¹³C NMR. The accuracy depends on the molecular complexity, solvent, and the quality of the prediction algorithm used.

What solvents are supported for chemical shift prediction?

This calculator supports common deuterated NMR solvents including CDCl₃, D₂O, DMSO-d₆, and CD₃OD. Each solvent has different effects on chemical shifts due to hydrogen bonding and polarity differences.

What is a SMILES string and how do I use it?

SMILES (Simplified Molecular-Input Line-Entry System) is a text notation for describing molecular structures. For example, 'CCO' represents ethanol. You can draw structures in chemical drawing software and export as SMILES or find SMILES codes in chemical databases.

What's the difference between TMS, DSS, and TSP references?

TMS (tetramethylsilane) is the standard reference for organic solvents, set to 0 ppm. DSS is used for aqueous solutions, and TSP is an alternative aqueous reference. The choice affects the absolute chemical shift values reported.

Can this calculator predict coupling constants and multiplicities?

This calculator focuses primarily on chemical shift prediction. While it can estimate basic multiplicities based on molecular connectivity, detailed coupling constant prediction requires more specialized quantum mechanical calculations.

What types of molecules work best with NMR prediction?

Small to medium-sized organic molecules with common atoms (C, H, N, O, S, P, F, Cl) work best. Very large molecules, metal complexes, or highly strained structures may have less accurate predictions due to computational limitations.

How does spectrometer frequency affect chemical shift predictions?

Chemical shifts in ppm are theoretically frequency-independent, but higher field strengths (higher MHz) can provide better resolution and more accurate experimental validation of predicted values. The calculator accounts for field-dependent effects where relevant.