Last updated: June 2026
Use this Proton NMR Solver to practise 1H NMR integration, splitting, chemical shift and structure deduction for common A-Level and Singapore H2 Chemistry questions.
How the Proton NMR Spectrum Helper works
Enter the chemical shift, multiplicity, integration and coupling constant for each signal. The helper scales integrations, explains simple n + 1 splitting, suggests likely proton environments and draws a simplified stick spectrum.
Peak data can also be pasted in forms such as:
7.10–7.35 m 5H
4.10 q 2H J=7
1.25 t 3H J=7
How to solve a proton NMR spectrum
Begin with the molecular formula and calculate the degree of unsaturation. Then count the signals, scale the integration ratio, interpret the splitting pattern and finally use chemical shift to identify the likely proton environments.
- Calculate degree of unsaturation from the molecular formula.
- Count the number of different proton environments.
- Scale the integration ratio to the total number of hydrogen atoms.
- Use splitting to identify neighbouring non-equivalent protons.
- Use chemical shift to decide which functional groups fit.
- Check that one proposed structure explains every signal.
Proton NMR integration
Integration gives the relative number of protons responsible for each signal. For example, a ratio of 3:2:1 can represent 3H, 2H and 1H when the molecular formula contains six hydrogen atoms.
Proton NMR splitting and the n + 1 rule
In simple first-order spectra, a set of protons with n adjacent non-equivalent protons is split into n + 1 lines. Equivalent protons do not normally split one another.
| Adjacent non-equivalent protons | Expected pattern |
|---|---|
| 0 | Singlet |
| 1 | Doublet |
| 2 | Triplet |
| 3 | Quartet |
| 4 | Quintet |
| 5 | Sextet |
| 6 | Septet |
Approximate proton NMR chemical shifts
| Approximate δ / ppm | Common environment |
|---|---|
| 0.8–1.5 | Simple alkyl H |
| 1.5–3.0 | Allylic, benzylic or next to C=O |
| 3.0–4.5 | On carbon next to O, N or halogen |
| 4.5–6.5 | Alkene H |
| 6.5–8.5 | Aromatic H |
| 9.0–10.0 | Aldehyde H |
| 10.0–13.0 | Carboxylic acid O–H |
Useful patterns to recognise
An ethyl group often gives a 3H triplet and a 2H quartet with similar coupling constants. An isopropyl group often gives a 6H doublet and a 1H septet. A 3H singlet near 2 ppm can indicate CH3CO, while a signal near 9–10 ppm strongly suggests an aldehyde proton.
Worked pattern: ethyl ethanoate
Ethyl ethanoate, CH3COOCH2CH3, commonly gives a 3H singlet near 2.0 ppm, a 2H quartet near 4.1 ppm and a 3H triplet near 1.2 ppm. The quartet and triplet reveal an ethyl group, while the downfield CH2 signal shows that it is attached to oxygen.
Common proton NMR exam traps
Frequently asked questions
Can this solver identify a unique structure?
It can recognise strong patterns and suggest plausible candidates, but the final structure must satisfy the molecular formula and all available evidence, including IR or mass spectrometry when provided.
Why can an integration ratio contain decimals?
Raw integration values are measured areas and may not be exact whole numbers. Divide by the smallest value and then scale to a sensible whole-number ratio.
Why do some signals not follow the n + 1 rule?
The n + 1 rule assumes simple first-order coupling. Overlapping signals, non-equivalent neighbouring groups, exchangeable protons and more complex spin systems can produce different patterns.