MP4 to FLV Converter

Convert an MP4 into an FLV for a legacy Flash player or system that still needs it. Free, in your browser, with no signup and no watermark.

Select MP4 file →

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Click or drag and drop to upload files

We support most file types including: MP4, MOV, WEBM, AVI, MP3, WAV, PNG, JPEG, GIF, MKV, PDF, FLAC, TIFF!

EchoWave is used by creators, marketers, educators, and businesses to convert and edit media online.

Updated June 2026

FLV is the old Flash Video format from the pre-HTML5 web. Browsers and Adobe dropped Flash support in 2020, so this conversion is for the narrow case where a legacy Flash player, an old authoring tool, or a specific system still demands a .flv file. EchoWave produces one for free in your browser with no signup. For anything modern, MP4 is the format you actually want.

Free, no sign-upNo account, no trial

Runs in your browserNothing to install

Works on every devicePhone, tablet, laptop

No watermarkClean output, every time

How it works

How to convert MP4 to FLV

1
Upload your MP4
Drag your MP4 onto the converter or pick it from your device. Nothing to install.
2
Choose FLV and convert
Select FLV as the output and start. Free, with no sign-up and no watermark.
3
Download your FLV
Save the finished FLV, or open it in the editor to trim, crop, or resize it first.

Try it

Estimate your FLV

Pick a video bitrate and a length to see the FLV file size before you convert.

Video bitrate

Length5 min

1 min30 min

Estimated FLV size183MBSharp 1080p

An estimate. Real size varies with resolution, frame rate, and how much the picture moves.

The formats

MP4 vs FLV

MP4

MPEG-4 Part 14

The video format that plays everywhere

Type: Video container
Holds: H.264 video plus AAC audio, sometimes subtitles
Typical size: Large, it carries video
Plays on: Phones, browsers, TVs, almost any player

Best for:Watching and sharing video

FLV

Flash Video

Legacy Flash video from the pre-HTML5 web

Type: Flash video container
Holds: H.263, VP6, or H.264 video with MP3 or AAC audio
Typical size: Small, made for streaming
Plays on: VLC, since browsers dropped Flash in 2020

Best for:Recovering old Flash web video

Will it lose quality?

When the codecs already match FLV, the converter can change the container without re-encoding, so the picture stays identical.
When the video has to be re-encoded for FLV, a high bitrate keeps it visually close to the MP4.
Converting cannot add detail the MP4 never had. The output is at best as good as the source.

Use cases

What people use it for

Play anywhereMake a clip your device supports

Video editorsGet footage your software accepts

Web videoUse a format browsers play

CourseworkHand in a standard video file

SharingSend a clip people can open

Troubleshooting

If something looks off

The FLV will not play

Some players are picky about codecs. Try it in VLC, which opens almost anything, or convert again and let the converter re-encode the video.

The file got larger

A format change can shift the size, and re-encoding at a high bitrate adds overhead. Lower the bitrate or trim the clip for a smaller file.

Audio and video drift out of sync

Re-download the source and convert again. If a long recording drifts, splitting it into shorter pieces usually fixes the sync.

FAQ

MP4 to FLV questions

Is the MP4 to FLV converter free?

Yes. EchoWave converts MP4 to FLV with no signup, no file-count limit, no trial, and no watermark. Upload your video, convert it, and download the FLV from your browser.

How do I convert MP4 to FLV?

Upload your MP4, choose FLV as the output, and start. When it finishes, download the FLV or open it in the editor to trim the clip first.

Should I still use FLV in 2026?

For new work, no. Web browsers and Adobe ended Flash support in 2020, so FLV will not play in a normal browser anymore. Only convert to FLV when an old Flash projector, authoring program, or legacy system specifically requires the .flv container.

What plays FLV files now that Flash is gone?

Standalone players like VLC still open FLV, but browsers do not. If you simply need the video to play, convert to MP4 instead, which works everywhere with no plugin.

Will converting MP4 to FLV reduce quality?

The video is re-encoded for the FLV container, so a high bitrate keeps it close to the source. FLV was built for small, streamable files, so converting cannot improve on the original MP4.

Why is the FLV smaller than my MP4?

FLV was designed for low-bandwidth streaming, so it leans toward smaller, more compressed files. A smaller size at the same length usually means more compression, not better quality.

Does the MP4 to FLV converter work on Mac, Windows, iPhone, and Android?

Yes. Building the FLV happens in a browser tab, so you can do it from Windows, macOS, a Chromebook, Linux, an iPhone, an iPad, or Android without installing anything. Bear in mind the .flv you download is meant for a legacy Flash player, not for the browser you converted it in, since modern browsers no longer run Flash.

Can I convert large videos to FLV?

Yes. There are no file-count limits, and large videos are supported. They simply take a little longer to upload and convert.