---
title: NMR Analyser plugin
url: https://www.moldraw.com/docs/plugins/nmr-analyser-plugin-predict-1h-13c-and-2d-nmr-spectra/
section: Plugins
updated: 2026-10-11
publisher: LabCanvas
---

# NMR Analyser plugin

> Install NMR Analyser from Settings, Plugins, draw a molecule, open the NMR tab, pick an experiment and press Predict.

![MolDraw NMR Analyser showing a predicted 1H NMR spectrum of chloramphenicol with a peak table](https://www.moldraw.com/docs/img/plugin-nmr-analyser-annotated-screenshot.webp)
*Predicted 1H spectrum of chloramphenicol. Each signal has a letter. The table lists shift, integral, splitting and J.*

1. NMR tab in the right-hand analysis panel.
2. Experiment buttons: 1H, 13C, COSY, HSQC, HMBC.
3. Predict runs the prediction for the current canvas structure.
4. Labels / Signals toggle peak letters and the signal list.

## What it does

The plugin predicts NMR spectra for the structure on your canvas.

- 1D 1H and 13C spectra show peaks with letters.
- The table gives shift, integral, splitting and coupling constant for each letter.
- 2D COSY, HSQC and HMBC show as contour plots. You can see which atoms are linked.
- Each run goes into **History**. Switch between molecules or experiments there.

To learn the basics, read [How to read an NMR spectrum](https://www.moldraw.com/guides/how-to-read-nmr-spectrum/).

## Who it is for

Students who check a structure against a lab spectrum. Teachers who make worked examples. Chemists who want a quick sanity check.

## How to use it

1. Open the [MolDraw editor](https://www.moldraw.com/) and sign in. Click **Settings**, then **Plugins**, then **Install** next to NMR Analyser.
2. Draw or paste your structure (e.g. paste a SMILES with **Paste SMILES**).
3. Open the **NMR** tab in the right panel (callout 1).
4. Choose the experiment, **1H** or **13C** for 1D, or COSY/HSQC/HMBC for 2D (callout 2).
5. Press **Predict** (callout 3). The spectrum appears in a few seconds.
6. Drag a box to zoom into a ppm range, scroll to scale intensity, double-click to reset.
7. Turn on **Labels** (callout 4) to match peak letters with the table and hover a row to highlight the atoms.
8. Export the plot (PNG/SVG) or the peak list (CSV) with the download button.

## Tips

- Draw explicit stereochemistry: diastereotopic protons can give different predicted shifts.
- Use HSQC to assign which H sits on which C, then HMBC to connect fragments across quaternary carbons.
- Predictions are for CDCl3-like conditions; OH/NH shifts vary a lot with solvent and concentration.
- New to NMR. Read [how to read an NMR spectrum](https://www.moldraw.com/guides/how-to-read-nmr-spectrum/) first.

## Questions and answers

**How accurate is the predicted NMR?**
Typical 1H predictions fall within about 0.2 to 0.3 ppm and 13C within a few ppm for common organic molecules. Exchangeable OH/NH protons and unusual ring systems can deviate more, so treat predictions as a guide, not a measured spectrum.

**Does the NMR Analyser need an account?**
Yes. Plugins are installed to your free MolDraw account. For a no-login quick check, use the free structure to NMR tool.

**Can it predict 2D NMR?**
Yes: COSY, HSQC and HMBC are drawn as contour plots alongside the 1D 1H and 13C spectra.

**Can I export the spectrum?**
Yes. Download the plot as PNG or SVG and the peak table as CSV.