Hit a 100 KB, 200 KB, or 500 KB attachment cap

Mailbox providers often allow a large message. A job form, a school portal, or a ticketing inbox may still say “max 200 KB per image.” LocalPix Compress to KB binary-searches JPEG quality in the tab until it is near the target you type, or until it cannot get closer without giving up. The number it prints is the file you download — confirm that against the form, because MIME overhead can add a little.

PNG screenshots have their own notes: Compress PNG for email size limits. Use that page when you are shrinking UI shots and deciding whether JPEG is acceptable. Use this page when the cap itself is the problem.

Caps people actually type

• 100 KB — tight. Fine for a simple logo-like graphic or a small headshot. A 12-megapixel photo will look soft. Crop to the useful region first.
• 200 KB — a common “one picture in the reply” budget when the text in the image still needs to be readable.
• 500 KB — enough for many application photos and product stills when the portal is stricter than email but not tiny.

These are planning numbers, not a promise from any host. If the form says 150 KB, type 150, not a round number you prefer.

Steps (local, 0-byte upload)

1. Open Compress to KB. If you want proof first, use Verify local or the homepage checklist.
2. Drop a PNG, JPEG, or WebP. HEIC from an iPhone will not decode here — convert with HEIC to JPG first (guide).
3. Set Target KB to the cap (100, 200, 500, or the exact figure). Run Compress.
4. Read the status line. “Best-effort” means the file can land a little off the target, or look worse than you hoped if the target is unrealistic.
5. Download the JPEG via the local blob: URL and attach that file.

When the result is the wrong kind of small

• Text is blurry. Raise the target. A readable 400 KB file beats an illegible 100 KB file that the portal accepts and a human rejects.
• Transparency disappeared. The tool encodes JPEG. Alpha becomes a flat background. For a cutout you must keep, stay on PNG from Remove background.
• Already under the cap. Do not recompress. A second pass only adds artifacts.
• WebP or AVIF the form will not open. Convert to JPG first: WebP and AVIF for inboxes that reject them, then compress if the JPG is still over the cap.

Related

Compress to KB · Compress PNG for email · HEIC to JPG · Verify local