How to Compress an Image to an Exact File Size

Hit any target size in three steps

1. Open Target File Size and drop your image.
2. Type the exact limit — 100 KB, 200 KB, whatever the form demands — and download.
3. If the form also restricts dimensions (many passport portals do), resize first with the Image Resizer, then apply the target size.

The tool iterates quality automatically until the file lands under your limit — no trial-and-error with sliders, no overshooting the cap by 2 KB and getting rejected.

Where exact-size limits come from

Size caps exist because forms flow through legacy government and enterprise systems built when 100 KB was a lot of data. That's also why the limits are strict: many portals hard-reject uploads even 1 KB over. Common real-world limits you'll hit:

• Passport and visa photos: 50–240 KB, often with exact pixel dimensions required too.
• Job applications (profile photos, CV scans): 100–500 KB.
• Exam and admission forms: 20–100 KB for signature images, 100–500 KB for photos.
• Email attachments in corporate environments: total limits around 10–25 MB make per-image targets useful.

What to sacrifice last: the quality ladder

When a tight limit forces real loss, the order in which you give things up matters more than the compression itself:

1. First: metadata. EXIF, GPS, thumbnails — pure overhead, zero visual cost, often saves 5–15% alone.
2. Second: dimensions. A photo destined for a 600×600 box doesn't need 3000 pixels. Resize to the required size (or 1.5× it at most) — this is the biggest lever and costs nothing visible at display size.
3. Third: format. Switching PNG screenshots to JPG, or JPG to WebP where accepted, multiplies the effect of the next step.
4. Last: quality. Only after the above should quality come down — and by then, 70 usually fits without visible damage.

Resizing first is the single most common fix: people try to squeeze a 4000-pixel photo into 100 KB with quality alone, when shrinking it to 800 pixels would get them there at quality 85.

Signature and document images: a special case

Signature scans and stamped documents are usually black ink on white paper. They compress extremely well if you prepare them: crop tightly to the signature, increase contrast so the background is pure white, convert to greyscale or JPG, then apply the target size. A messy phone photo of a signature that won't fit 20 KB will usually fit after a tight crop and a contrast boost — no quality heroics required.

Format choice changes everything at tight limits

The same target size hides wildly different quality outcomes depending on format. A screenshot stored as PNG at 100 KB might look perfect, while the same screenshot forced into a 100 KB JPEG shows ringing around every character — JPEG spends its bits badly on sharp edges. Conversely, a photograph as a 100 KB PNG is often impossible at any reasonable resolution, while a 100 KB JPEG of the same photo can look excellent.

So the sequence that wins at strict caps: ask what the image is, pick the format that handles that content best (photos → JPG, flat graphics → PNG or WebP, everything web-bound → consider WebP), resize to the minimum acceptable dimensions, then let the target-size tool find the best quality that fits. Forms usually accept JPG or PNG; some accept WebP; almost none accept anything else, so the exotic formats rarely help here. If a form explicitly demands JPG and your source is a crisp PNG screenshot, expect visible trade-offs — that's the format's nature, not the tool's.

One more trick for stubborn cases: greyscale. Colour information costs bits in every format, and for signature scans, stamped documents and printed forms, colour carries no information anyway. Converting to greyscale typically buys 20–40% more quality headroom at the same file size.

If the result looks bad anyway

At very aggressive targets, artefacts are inevitable. Three rescue options, in order of effectiveness: resize smaller (smaller images tolerate lower quality far better), convert to greyscale (removes colour information the encoder must spend bits on), and as a last resort crop to just the essential region. A crisp 400-pixel image beats a mushy 1000-pixel one in every form review — officials care that the photo is legible, not that it's large.