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Difference Between FFT and DFT

Difference Between FFT and DFT

Whether you’re a beginner signal processing enthusiast or an experienced professional, knowing the difference between Fast Fourier Transform (FFT) and Discrete Fourier Transform (DFT) is essential for understanding which type of algorithm is best suited to specific tasks. FFTs offer computational efficiency at the expense of slightly less precision when compared to DFTs. Additionally, FFTs require fewer calculations than DFTs when decomposing signals into their frequency components – this can be particularly beneficial for quickly analyzing data in real time. In this blog post, we’ll explore the differences between FFT and DFT algorithms in detail and provide examples of how each type is used in everyday applications.

What is FFT?

FFT (Fast Fourier Transform) is a powerful mathematical method used to convert signals from the time domain to the frequency domain. FFT has been around for decades but it was not used so widely until digital computing made it possible to calculate FFT at a much faster rate, thus leading to its widespread adoption across a variety of domains such as engineering and science.

FFT is also proven to be an efficient algorithm for various machine learning tasks, where the FFT process can be implemented with fewer computations required as compared to other methods. FFT can be applied on almost any type of data such as images, audio, and video in order to identify components and low-level features which would otherwise be difficult or impossible to detect using other methods.

What is DFT?

DFT is a powerful tool used by engineers and scientists to decompose complex signals into their component frequencies. DFT relies on mathematical equations that transform a time-based signal into its spectrum of frequencies. By using DFT, it is possible to understand the frequency content of any given signal and examine the amplitudes at each frequency component. DFT can then be combined with other tools to identify which individual frequency components need modification or amplification in order to take advantage of the full range of audio possibilities. DFT is an incredibly important asset for anyone who wants to create or modify the sound.

Difference Between FFT and DFT

FFT and DFT are both Digital Signal Processing (DSP) algorithms used to analyze a large amount of data.

  • FFT stands for Fast Fourier Transform which is an improved version of the Discrete Fourier Transform (DFT).
  • FFT is faster with lower computation complexity while DFT requires more computational power.
  • FFT can be implemented in hardware while DFT needs to be done in the software domain.
  • FFT divides the task into several short computations instead of one big computation, thus reducing overall complexity making it faster than the DFT algorithm.
  • FFT uses fewer number of complex arithmetic operations compared to DFT and is able to process more information per unit of time.

Overall, FFT greatly reduces the time required for DSP algorithms processing a tremendous amount of data as compared to DFT.


The main difference between FFT and DFT is that the FFT is an algorithm to compute the discrete Fourier transform while the DFT is a method to calculate the discrete Fourier transform. In other words, FFT is used to find out how much of each sinusoid component exists in a given signal while DFT determines exactly where these sinusoids exist in the frequency domain. Another significant difference between FFT and DFT is that the time taken by FTT for processing signals sampled at high rates is lesser than that of DFS.

This happens because a Fast Fourier Transform breaks down a long sequence into smaller pieces which are easier to handle whereas Discrete Fourier Transform processes every sample independently. However, both these methods have their own drawbacks as well; The major disadvantage with FTT is its usage of extra memory for storing results of intermediate calculations while working on a lengthy data set mightléad to problems like numerical instability in the case of DFS.

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