Get your video attachments under the Yahoo Mail limit
Drop a video and FitSize shrinks it so your message goes through Yahoo Mail, in your browser. Nothing is uploaded to a server.
Instant client-side compression · Up to 2 GB per file · Zero server upload
- Current limit
- 25 MB
- FitSize aims for
- 18.1 MB (room for email encoding)
- Last checked
- 30 September 2026
- Read on
- help.yahoo.com
Yahoo's limit is about the whole message, not about a single file. Three attachments that are each small can add up to a refusal, and the same limit applies to mail you receive, so a big attachment can fail on the way in as well as on the way out. This page is about getting the total down, not just one file.
Why Yahoo Mail has this limit
Why does Yahoo Mail refuse your attachment? Yahoo Mail caps total message size at 25 MB, causing upload errors or forcing third-party cloud links when exceeded. FitSize uses in-browser W3C WebCodecs and OPFS processing to compress your files under the ceiling with zero-byte server upload privacy.
Yahoo's help page states the limit but not the reasoning: the sum of all attached files in a single message, incoming and outgoing, must not exceed it. As with every email provider, attachments travel encoded and become larger in transit, which is why FitSize aims below the number on the page.
Our reasoning, from help.yahoo.com , proton.me
What FitSize does with your file
Yahoo adds up every attachment in the message, so FitSize's target is for the total, not per file: if you are sending several files, compress them to a shared budget rather than one at a time. The target leaves room for encoding, and the page shows you the real usable size.
Best fit for a 30-second clip at 18.1 MB: 720p at Balanced quality (that resolution holds up to 59 s). Best fit for a 2-minute clip at 18.1 MB: 480p at Balanced quality (that resolution holds up to 2 min 05 s).
Your file never leaves your device. It is read and compressed by your browser, and nothing is uploaded to a server.
Three things to watch on Yahoo Mail
- It is a sum, not a per-file limit. The sum of all attached files in a single message must not exceed the limit, so several small files can add up to a refusal. Compress the set, not just the biggest file. Source: help.yahoo.com
- It applies to incoming mail too. The limit covers both incoming and outgoing email, so a message with a large attachment can be refused when it is sent to you as well as when you send it. If you are the recipient, ask the sender to compress before sending. Source: help.yahoo.com
- Yahoo does not say whether encoding counts. The help page does not say whether the limit is measured on the encoded message, so FitSize assumes it is and aims for 18.1 MB. If you are close to the limit and it still fails, splitting the files across two messages is the reliable fallback. Our reasoning, from help.yahoo.com , proton.me
FitSize vs traditional cloud converters
| Architecture Feature | FitSize (In-Browser) | Traditional Cloud Converters |
|---|---|---|
| Latency | Instant / 0s queue delay | 15–45s upload queue & network delay |
| Privacy | 0-Byte Server Upload (100% on-device) | Files uploaded & stored on third-party servers |
| Bandwidth | 0 MB upload bandwidth consumed | Full upload and download bandwidth consumed |
| Exact File Size Guarantee | Deterministic bit-budget target | Trial-and-error guesswork re-compression |
Frequently asked questions about Yahoo Mail compression
What is the attachment size limit on Yahoo Mail?
Yahoo Mail permits attachments up to 25 MB per email. Exceeding this limit prompts you to upload files to external cloud storage or aborts the message draft entirely.
How can I fit large video files into a standard Yahoo email?
Compress the video using FitSize's 18 MB email target. This accounts for MIME transport overhead, allowing the message to send directly through Yahoo's mail servers.
Does FitSize store or log my Yahoo Mail files?
Never. FitSize runs entirely in client-side JavaScript and WebCodecs without server backends. Your media files remain on your local drive with zero cloud storage or logging.