Compress Image to Exact Size
Auto-tune quality and downscale until the image fits under your KB target — privately in your browser.
Drop an image to compress to an exact KB target
Binary-searches quality and downscale until the result fits
How to compress an image to an exact size
Drop your image into the box above. Pick a preset (50, 100, 200, 500 KB, 1 MB, 2 MB) or type a custom KB number. Click Compress. The tool runs a binary search: it tries the image at multiple quality and downscale levels until the encoded blob fits under your target. You get the result plus a transparent log: the quality picked, the scale used, and how many probes it took.
When to use a target-size compressor
- Passport / visa / ID photos — most government forms cap at 100–200 KB
- University and job applications — typical 1 MB hard cap on uploads
- Email attachments — keep under 25 MB total; target 1–2 MB per image
- Forum / job-portal avatars — usually 50–200 KB
- Bulk thumbnail generation — target 50 KB for consistent server load
What you can do
- Presets for the six most-common sizes; custom KB target up to 20 MB
- JPEG output (universal) or WebP (smaller, modern browsers)
- Auto-downscale when quality alone cannot reach the target
- Transparent report — chosen quality, scale, probe count
- No watermark, no signup, no upload
Frequently asked questions
How do I compress an image to an exact KB size?
Drop your image into the box above, pick a target (50, 100, 200, 500 KB or 1, 2 MB — or type a custom KB), and click Compress. The tool tries multiple quality + downscale combinations until it finds one that fits under your target, then offers the result for download. No account, no upload.
How does the auto-compression actually work?
The tool runs a binary search. It tries the image at full size with maximum quality, then iteratively bisects either quality or scale until the encoded blob fits under your target. Each probe takes a few milliseconds in modern browsers; convergence usually happens in 5–15 probes.
Does ToolChop upload my image?
No. The entire compression loop runs in your browser via the Canvas API. Your image never leaves your device — there is no upload, no temporary storage, and no copy on our servers. That matters when the image is a passport/ID scan, medical document, or anything internal.
What is the difference between this and the regular Compress Image tool?
The regular tool gives you a quality slider — you pick a level and see the result. This tool is the inverse: you pick a target file size and it picks the best quality/scale for you. Use this when an upload form has a hard size limit (passport photos, government forms, university applications).
Will my image look noticeably worse at 100 KB?
Depends on the input. A 1920 × 1080 photo at 100 KB is moderately compressed (Q60–70) but still looks fine in normal viewing. A 4000 × 3000 photo at 100 KB requires aggressive downscaling — the tool will reduce dimensions automatically. If you see softness, the dimensions probably dropped; check the chosen scale percentage in the result.
Why does the result sometimes overshoot my target?
If your target is much smaller than the input can reach without distortion, the tool surfaces the smallest result it could produce and flags it as best-effort. Practical example: a 4K photo compressed to under 20 KB will end up around 25–30 KB even at minimum quality and 30% scale. Raise the target or pre-crop the image.
Should I pick JPEG or WebP?
JPEG is the right default — every site, government portal, and OS accepts it. WebP is 25–35% smaller at the same visual quality but a small number of corporate upload forms still reject it. If the destination supports WebP, use it.
What targets are common?
Government forms and visa applications typically cap photos at 100–200 KB. University applications often accept up to 1 MB. Email attachments are fine up to 25 MB but many people prefer 1–2 MB per image. WhatsApp web compresses anything you upload, so a 500 KB target is usually plenty.
Why does the output dimension shrink?
When the target is too tight for the current dimensions to reach at any quality, the tool steps the scale down (85% → 70% → 55% → 40% → 30%) and tries again. This is how online sites like 'photo for passport' produce sub-100-KB images from multi-megapixel inputs.
Is there a maximum target size?
20 MB. Above that there is no real compression problem — most originals are already under that. If you need 20 MB+ exactly, use a hex editor to pad the file (technically the only way to enforce a minimum size).
Why is the result still slightly over the target?
JPEG and WebP encoders do not give you direct byte-level control — they pick quantization based on quality. The binary search gets very close (typically within 5%). If the result is slightly over and the destination is strict, drop the target by ~5% (e.g. ask for 95 KB to safely hit 100 KB).
Can I batch compress to a target size?
Right now the tool handles one image at a time so you can see the chosen quality and dimensions. Batch mode is on the roadmap. For now, drop each image in sequence — each one converges in under a second on a modern laptop.
Why use ToolChop instead of ilovepdf or imresizer?
Both upload your file to a server. For ID scans, passport photos, medical records, or anything internal, that is an unnecessary risk. ToolChop runs the entire binary-search compression in your browser. Same workflow, fully private.