NMR Chemical Shift Calculator
ppm to hertz, and why only one of them is portable.
Work out NMR Chemical Shift. ppm to hertz, and why only one of them is portable. Free, with no account and nothing to download.
The ¹H frequency of the instrument — 300, 400, 500, 600, 800.
Chemical shift
7.26 ppm
2,178 Hz at 300 MHz — Aromatic
ppm exists so that shifts are comparable between instruments. A peak at 7.26 ppm is at 7.26 ppm on every spectrometer, while in hertz it moves with field strength — 2,178 Hz on a 300 MHz magnet and 5,808 Hz on an 800. Coupling constants behave the opposite way. J values are a property of the bonding, fixed in hertz and field-independent, which is why they are always quoted in Hz and never in ppm. If a splitting appears to change size in ppm between two instruments, that is exactly what should happen. The region given here is a rough guide for ¹H. Substituent effects shift things considerably, and the assignment should always be confirmed by integration and coupling rather than position alone.
How the NMR Chemical Shift Calculator works
Convert a chemical shift between ppm and hertz for any spectrometer frequency, with the typical ¹H assignment for that region. The conversion is simple; the reason it matters is that ppm is field-independent and hertz is not.
Also known as: ppm to hz nmr converter · chemical shift converter · nmr frequency calculator · hz to ppm nmr
Frequently asked questions
How do I convert ppm to Hz in NMR?
Multiply the shift in ppm by the spectrometer frequency in MHz. A peak at 7.26 ppm on a 300 MHz instrument is at 2,178 Hz.
Why are chemical shifts reported in ppm?
So they are comparable between instruments. The same proton appears at the same ppm on any spectrometer, while its position in hertz scales with field strength — which would make published data useless without stating the magnet.
Why are coupling constants reported in Hz?
Because J is a property of the bonding and does not change with field strength. Expressed in ppm it would appear to shrink on a bigger magnet, which is exactly backwards from how a physical constant should behave.
Why does a stronger magnet give better resolution?
Because chemical shifts spread out in hertz while couplings stay fixed. Two peaks 0.02 ppm apart are 8 Hz apart at 400 MHz and 16 Hz at 800, so overlapping multiplets separate cleanly at higher field.
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