Compress a file for email
Mail services accept attachments of roughly 20–25 MB. But the real allowance is smaller than the number they quote — and that is the first thing to know.
Select the files you want to compress or convert and upload them here.
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Supported compression and conversion formats:
JPEG, JPG, PNG, GIF, WEBP, MP3, TIFF, TIF, BMP, DIB, RLE, JP2, JPF, JPG2, JPX, J2K, JPC, MJ2, OGG, OGV, SPX, WAV, 3GP, AAC, M4A, M4B, OPUS, OGA, MP4, AVI, MKV, MKA, SVG, EXR, RAW, ARW, SRF, SR2, CRW, CR2, CR3, DNG, DCR, KDC, ERF, 3FR, MEF, MRW, NEF, NRW, ORF, PEF, RAF, RWL, RW2, SRW, X3F, PDF, JXL.
The real limit is smaller than the number
Email travels as text, so any attachment is re-encoded into letters and digits — a scheme called base64. Encoding inflates the file by about a third: three bytes become four characters.
Hence the rule: to fit a stated 25 MB, the file should weigh around 18 MB; for a 20 MB limit, about 15 MB. That is why a message carrying an attachment of "exactly 25 MB" bounces even though it formally fits.
What to do with each kind of file
Documents and scans: a black-and-white TIFF scan shrinks tenfold or more with no quality loss at all, and a PDF slims down through the images inside it — the text weighs almost nothing.
Photographs: a 5 MB phone shot at 70–80% quality lands around a megabyte, so a whole shoot fits into one message.
Audio: an hour of speech at 64 kbps mono is about 27 MB — already past the edge, so use 48 kbps for long recordings.
Video: the honest answer is that email is the wrong channel. Around two minutes of 480p fit into 18 MB; anything longer goes to cloud storage and travels as a link.
| Service | Stated limit | How big the file may be |
|---|---|---|
| Gmail | 25 MB | about 18 MB |
| Outlook | 20 MB | about 15 MB |
| Mail.ru | 25 MB | about 18 MB |
| Yandex Mail | 30 MB | about 22 MB |
Common questions
Why won't my message send when the file is under the limit?
Because attachments are encoded as text and take about a third more room in the message than on disk. Aim for 18 MB against a 25 MB limit, and 15 MB against a 20 MB one.
How do I send a file larger than 25 MB?
Either compress it to size, or upload it to cloud storage and put a link in the message. Major mail services offer the second route themselves when an attachment does not fit.
Does zipping help?
On documents and text, noticeably. On photos, music and video, hardly at all: they are already compressed and an archiver gains a few percent. Those files need re-compressing, not archiving.