FFT Resolution Calculator

Calculate the frequency resolution, number of bins, and maximum frequency of a Fast Fourier Transform.

Hz

Typically a power of 2

Frequency Resolution

46.875 Hz

Useful Frequency Bins513
Maximum Frequency24,000 Hz
Time Window Duration21.33 ms

Frequency Resolution vs Sampling Rate

FFT Frequency Resolution

The FFT converts time-domain data into frequency-domain bins. The resolution depends on how long you observe the signal.

Formulas

Frequency Resolution = Sample Rate / FFT Size

Time Window = FFT Size / Sample Rate

Useful Bins = FFT Size / 2 + 1 (for real signals)

Trade-off

Better frequency resolution requires longer observation windows. This is the time-frequency uncertainty principle.

  • Larger FFT = finer frequency resolution but slower updates
  • Smaller FFT = coarser resolution but faster updates
  • Example Calculation

    1024-point FFT at 48 kHz sampling rate.

    1. 01Resolution: 48,000 / 1,024 = 46.875 Hz
    2. 02Useful bins: 1024/2 + 1 = 513
    3. 03Max frequency: 48,000 / 2 = 24,000 Hz
    4. 04Time window: 1024/48,000 x 1000 = 21.33 ms

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