FFTW is a C subroutine library for computing the discrete Fourier transform (DFT) in one or more dimensions, of arbitrary input size, and of both real and complex data (as well as of even/odd data, i.e. the discrete cosine/sine transforms or DCT/DST). We believe that FFTW, which is free software, should become the FFT library of choice for most applications.

The latest official release of FFTW is version 3.3.10, available from our download page. Version 3.3 introduced support for the AVX x86 extensions, a distributed-memory implementation on top of MPI, and a Fortran 2003 API. Version 3.3.1 introduced support for the ARM Neon extensions. See the release notes for more information.

The FFTW package was developed at MIT by Matteo Frigo and Steven G. Johnson.

Our benchmarks, performed on on a variety of platforms, show that FFTW's performance is typically superior to that of other publicly available FFT software, and is even competitive with vendor-tuned codes. In contrast to vendor-tuned codes, however, FFTW's performance is portable: the same program will perform well on most architectures without modification. Hence the name, "FFTW," which stands for the somewhat whimsical title of "Fastest Fourier Transform in the West."

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FFTW 3.3.10 is the latest official version of FFTW (refer to the release notes to find out what is new). Here is a list of some of FFTW's more interesting features:

If you are still using FFTW 2.x, please note that FFTW 2.x was last updated in 1999 and it is obsolete. Please upgrade to FFTW 3.x. The API of FFTW 3.x is incompatible with that of FFTW 2.x, for reasons of performance and generality (see the FAQ or the manual).


First, read the FFTW Frequently Asked Questions document.

Manual: HTML or PDF.

man pages: the fftw-wisdom and fftw-wisdom-to-conf utilities.

For general questions about Fourier transforms, see our links to FFT-related resources. People often ask us how to compute a subset of the FFT outputs, so we have posted a short discussion of pruned FFTs.

We benchmarked FFTW against many other FFT programs, in one to three dimensions, on a variety of platforms. You can view the results from this benchmark, or download it to run on your own machine and compiler, at the benchFFT web page.

An audio interview of the FFTW authors is available from the RCE podcast program.


Versions 3.3.10 and 2.1.5 of FFTW may be downloaded from this site. Feel free to post FFTW on your own site, but be sure to tell us so that we can link to your page and notify you of updates to the software.



FFTW received the 1999 J. H. Wilkinson Prize for Numerical Software, which is awarded every four years to the software that "best addresses all phases of the preparation of high quality numerical software." Wilkinson was a seminal figure in modern numerical analysis as well as a key proponent of the notion of reusable, common libraries for scientific computing, and we are especially honored to receive this award in his memory.

Our paper "A Fast Fourier Transform Compiler" (in PLDI 1999) received the Most Influential PLDI Paper award in 2009.


We are grateful for the support of many people and companies, including Sun, Intel, the GNU project, and the Linux community. Please see the acknowledgements section of our manual for a more complete list of those who helped us. We are especially thankful to all of our users for their continuing support, feedback, and interest in the development of FFTW.

Related Links

We have put together a list of links to other interesting sites with FFT-related code or information. This should be helpful if you want to know more about Fourier transforms or if for some reason FFTW doesn't satisfy your needs.


If you have comments, questions, or suggestions regarding FFTW, don't hesitate to email us at We support encrypted/signed email. Use our public keys.