FREE REAL-SIGNAL DFT BIN CALCULATOR
Put a frequency grid around your samples.
Enter a sampling rate and transform length. Find bin spacing, see the odd or even endpoint, and optionally look up the nearest represented frequency.
No waveform is analysed. This calculates the grid a real-signal DFT uses.
Set the sampled record
CURRENT GRID
Bin spacing
Exact:
Decimal values are rounded. Exact fractions govern all calculations and the nearest-bin decision.
Represented indices:
bins, including DC at index 0
- Theoretical Nyquist, fs/2
- Exact:
- Highest represented bin
- Exact:
- Record duration, N/fs
- Exact:
- Last-sample offset, (Nā1)/fs
- Exact:
Nearest represented bin to the target
Index Ā·
Exact centre:
Signed centre minus target:
Exact signed error:
No target was supplied. The grid is calculated; target lookup is skipped.
A few represented bins
Endpoints and available neighbours of the chosen bin. This is a bounded example set, not a billion-row spectrum.
| Index k | Centre, rounded | Centre, exact | Note |
|---|
Keep the current calculation
Downloads include exact fractions and assumptions. No inputs or results are uploaded.
One missing endpoint can matter.
At a sampling rate of 100 Hz and N = 5, spacing is 20 Hz and the real-signal grid is 0, 20 and 40 Hz. The theoretical Nyquist frequency is 50 Hz, but it is not a represented bin for this odd transform length.
When N is even, the last nonnegative bin is at fs/2. Binspan shows both values so they do not get confused. Its index count includes the zero-frequency DC bin.