在线把视频压缩到 20 MB

设定精确的 20 MB 上限，下载无水印 MP4。

当上传表单、聊天软件或存储规则要求文件不超过 20 MB 时使用此目标。压缩器默认设为 19 MB，为编码波动留出余量。

把视频拖进来就开始点按选择视频

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支持 mp4, webm, mov, mkv, avi, wmv，共 33 种格式

输出文件大小：

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Where 20 MB comes from

Twenty megabytes now has two clear sources. Discord raised its free per-file limit to 20 MB in August 2026, and Microsoft documents 20 MB as the default total message size for internet email accounts in Outlook.

Discord — Free20 MB
The current free-account per-file upload ceiling.
Discord limits in full Discord — File Attachments FAQ Discord — Account caps @discord — 20 MB announcement, incl. the mobile measurement change (13 Aug 2026)verified 2026-09-14
Outlook — Outlook.com / internet email account20 MB
Microsoft’s documented default total message size for an internet email account.
Outlook limits in full Microsoft — Reduce attachment size to send large files with Outlookverified 2026-10-30

How long a video fits in 20 MB

The longest clip each resolution can carry inside 20 MB. “Comfortable” means the bitrate clears what that frame size wants; “watchable” means it is soft but holds together. Both columns are arithmetic on the size and the duration; the thresholds they are compared against are recommendations, documented under the table below.

Longest clip per resolution inside 20 MB
Resolution	Comfortable up to	Watchable up to	Needs
1440p	18s	29s	9,000 kbps
1080p	39s	77s	4,000 kbps
720p	70s(1 min)	133s	2,200 kbps
480p	145s(2 min)	261s	1,000 kbps
360p	225s(4 min)	384s	600 kbps

Method: 20 MB spread over the duration, minus 128 kbps of audio and 2% container overhead, then compared against H.264 thresholds derived from published bitrate ladders and reduced by about a third for re-encoded source. A minute inside 20 MB leaves 2612 kbps for video, which is exact. Which resolution that is enough for is a recommendation, not a measurement.

What 20 MB buys at each length

The table above reads by resolution; this one reads by duration. Same arithmetic, the other way round — pick your clip length and see what is left to spend.

视频时长	留给画面的码率	能撑住的分辨率	结论
15s	10,833 kbps	1440p	看着没问题
30s	5,353 kbps	1080p	看着没问题
1 min	2,612 kbps	720p	看着没问题
2 min	1,242 kbps	480p	看着没问题
5 min	420 kbps	360p	明显糊
10 min	146 kbps	—	明显糊

算法说明：码率这一列是纯算术——20 MB 摊到整段时长上，减去 128 kbps 的立体声音轨和 2% 的容器开销。这是硬上限，不是估算。分辨率和结论这两列是建议，依据是公开的 H.264 码率阶梯，并整体下调约三分之一——因为对已经压过一次的素材再编码，能承受的码率比编码原始母版更低。这里刻意保守：宁可说得难听点，也不想告诉你「没问题」结果画面糊掉。

20 MB 在不同时长和分辨率下的效果

左栏是每种时长可用于画面的码率，其他格子是各分辨率所需的码率。绿色表示余量充足，黄色表示能看但会偏软，灰色表示应该降低分辨率。沿着一列向下看，就能知道视频多长以后该分辨率不再适合 a 20 MB limit。

来源：计算结果，并非实测——生成此图时没有运行编码器 · 方法：把 20 MB 分摊到整段时长，减去 128 kbps 音频和 2% 容器开销。阈值来自公开的 H.264 码率阶梯，并针对二次编码素材下调约三分之一。

What goes wrong at 20 MB

The same number does not mean the same thing. Discord measures the file, so 19 MB is a safe direct target. Outlook measures the encoded message: base64 overhead makes a 20 MB raw video too large, so an email attachment needs to be closer to 14 MB.

如何把视频压缩到 20 MB

添加视频
压缩器已设为 19 MB，让结果稳妥低于 20 MB 上限。
长视频先剪辑
在 20 MB 内，时长比任何画质选项都更占预算。时长减半，每帧可用码率就翻倍。
下载并检查复杂画面
全尺寸查看运动、人物面部和渐变；这些区域最先暴露压缩损伤。

20 MB 压缩常见问题

怎样把视频压缩到 20 MB？

上传视频，保留“目标大小”模式，并使用 19 MB 预设。输出是无水印 H.264 MP4。

为什么目标是 19 MB，而不是正好 20 MB？

目标大小编码可能有轻微波动。留出一点余量，可让下载文件稳定低于 20 MB 硬上限。

长视频也能压进 20 MB 吗？

可以，但时长越长，可用码率越低。请用本页表格判断何时降低分辨率会比强行保留原尺寸更清晰。

Other target sizes

Not one of these? Work out any size and length in the calculator — same arithmetic, plus what we measured at the bitrate it gives you.