Read the limit as decimal (1 MB = 1,000,000 bytes), aim a little under it, and shrink images first: resolution, then color depth, then JPEG quality. Check the result at 100% before you send it. If the file still cannot get under the line legibly, split it instead of crushing it.
01First, the units
“MB” can mean 1,000,000 bytes or 1,048,576 bytes depending on who is counting. One court spells out its reading: “File sizes may be listed in KB (kilobytes) or megabyte (MB). 1000KB = 1MB. ECF will reject anything 50.0MB (50,000KB), or over.”[1] Most providers do not say. Using the decimal reading is the safe choice: a file under 12,000,000 bytes also fits a limit of 12 binary megabytes.
Watch the wording, too. USCIS says files “must not be larger than 12MB”,[2] so exactly 12 MB is fine. The court rejects “50.0MB (50,000KB), or over”,[1] so the file must be strictly under 50 MB. Email limits often cover the whole message: Yahoo’s is “The sum of all attached files in a single message”,[4] so two 15 MB files fail a 25 MB limit together.
02The dials, in the order that saves most
- 1. Image resolution. Scans and photos are usually stored at far more pixels per inch than the page needs on screen. Lowering resolution reduces pixels by the square: halving 300 ppi to 150 ppi keeps a quarter of the pixels.
- 2. Color depth. A clean typed page scanned in color stores three channels; grayscale stores one; black-and-white stores one bit per pixel. The court’s test of 317 pages: bitonal at 300 ppi was 23.86 MB, grayscale at 400 ppi was 374.47 MB.[1]
- 3. JPEG quality. Re-encoding photos at a lower quality setting trades fine detail for size. Text in a scan suffers first, so stop before letters blur.
- 4. Structure. Removing duplicate images, unused objects and metadata, and compressing object streams, saves less but costs no quality at all.
Aim for the number, not for the smallest file. A 3 MB scan that reads well beats a 300 KB one that an officer or clerk cannot read.
Our reading of [2]
03Check before you send
Open the compressed file and look at a dense page at 100%: small print, signatures, stamps and handwriting. USCIS’s rule for evidence is that “all text is readable”,[2] and that is a good test for any portal. Then check the size in your file manager in bytes, not the rounded number a browser shows.
04When to split instead
Some files cannot reach a target without becoming unreadable: a 300-page scanned exhibit will not fit in 2 MB. Courts expect this. The Northern District of California advises: “You may combine smaller exhibits into one file, as long as that file is under 50.0 MB. Or if needed, break your filing out into smaller sections.”[1] Split by size cuts a file into parts that each fit, at page boundaries.
05Common targets
| Destination | Limit | Reading |
|---|---|---|
| USCIS online evidence | 12 MB per file | “must not be larger than 12MB”[2] |
| Gmail (personal) | 25 MB | “the limit is 25 MB”[3] |
| Yahoo Mail | 25 MB for all attachments | “must not exceed 25MB in total file size”[4] |
| N.D. Cal. CM/ECF | Under 50 MB per file | “ECF will reject anything 50.0MB (50,000KB), or over.”[1] |
More destinations, with sources and checked dates, are on the upload limits page.
Every record on Upload limits opens the compressor with that target already set. It runs in your browser, so the document you are shrinking is never uploaded to us.
Limits change. Check the provider’s page, linked from each record, before a deadline.