Free tool · runs in your browser

Audio Speed Changer

Speed up or slow down audio anywhere from 0.25× to 4×, with pitch preserved for natural speech and music or deliberately shifted for the chipmunk / slowed effect. Uses FFmpeg's atempo filter (auto-chained for extreme rates), runs entirely in your browser, and never uploads your file.

How to use this tool

  1. 01

    Upload your audio

    Drop in or choose any format FFmpeg supports — it's processed locally and never uploaded.

  2. 02

    Set the speed multiplier

    0.5× for half speed, 2× for double — anywhere from 0.25× to 4× is supported.

  3. 03

    Choose pitch handling

    Preserve pitch for natural speech and music; allow pitch shift for the chipmunk / slowed effect.

  4. 04

    Render and download

    Output duration scales inversely with speed; preview, then download the adjusted file.

Why this matters

Listening to lectures, audiobooks, and podcasts at 1.25×–1.5× is one of the highest-leverage time savings most people can make, and on the slow side transcribers, musicians learning a part by ear, and language learners all need to drag material down to a workable pace. The catch is that a naive speed change shifts pitch — voices go cartoonish or muddy — which makes the result useless for the very tasks people change audio speed for.

This tool keeps pitch natural by default using FFmpeg's atempo filter (auto-chained so the full 0.25×–4× range stays artifact-free), and still offers the deliberate pitch-shift effect when you want it — all in your browser with no upload. Pair it with the Audio Trimmer to cut to just the section you need first, then change its speed for review or practice.

Related tools

Video Speed Changer

Speed up or slow down any video from 0.25× to 4× in your browser. Pitch-preserving audio with the atempo filter, no upload, no signup.

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Audio Trimmer

Trim audio to a precise start and end with HH:MM:SS inputs and lossless stream-copy — all in your browser. No upload, no quality loss, no signup.

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Audio Fade In/Out

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FAQ

Almost always for speech: preserving pitch keeps a voice sounding like the same person at 1.5×, whereas shifting it makes it cartoonish and harder to follow. It matters for music too — moving pitch detunes everything and breaks the harmony. Turn pitch preservation off only when you specifically want the chipmunk or slowed-down-record effect.

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