Document Scan Compressor
Certificate and document photos can exceed a portal's upload limit even when the page is clearly readable. Reduce the file toward the required KB ceiling, then zoom in on small print and stamps before submitting the download.
Your document or certificate scan is compressed locally in your browser so sensitive paperwork never leaves your device. Temporary tab memory is emptied as soon as you close or refresh the page.
Drop your image here
or choose an image from your device
Accepts JPG, PNG or WEBP. Strong compression can make small print on a scan hard to read.
Need your documents as one PDF? Convert images to PDF.
When you need this
- Uploading a certificate or marksheet to a portal with a KB limit
- Emailing a scanned document without hitting an attachment cap
- Reducing a stack of phone-camera scans before submitting them
How document scan legibility and JPEG block compression interact
Scanned certificates, marksheets and tax forms consist of sharp, high-contrast transitions between dark ink and light paper. Because JPEG compression divides an image into 8×8 pixel blocks and discards high-frequency detail first, pushing JPEG quality too low on a 12-megapixel camera photo creates faint grey 'mosquito noise' halos around every letter while still spending bytes on paper grain.
The most reliable way to hit a 100–200 KB portal limit without blurring small print is to crop away the table edges and keep pixel dimensions sensible (around 1600–2000 pixels on the long side for an A4 sheet) so the encoder can use a higher quality level on the text itself:
- Full A4 certificate or marksheet (150–200 KB target): best around 1600–2000 px on the long edge so 8-point serial numbers and dates remain sharp.
- Single ID card or PAN/driver licence scan (50–100 KB target): crop tightly to the card border; 1000–1200 px width holds every character clearly.
- Black-and-white printed forms: running the scan through Grayscale Image first strips colour cast from indoor lighting and leaves more byte budget for crisp text edges.
Limitations
Compression is lossy JPEG encoding guided by your KB target. It does not sharpen text, straighten skewed pages or remove shadows from a phone photo.
- Very low targets can make small print unreadable even when the file fits.
- Multi-page documents must be processed one image at a time.
- PDF files are not supported.
Troubleshooting
A scan that will not fit usually has far more pixels than the document needs.
- Text blurry at the target: reduce dimensions with Resize Image first, then compress — fewer pixels at higher quality reads better.
- Grey, uneven paper background: convert to grayscale before compressing to remove colour noise.
- Output still above target: the result panel shows the real size; lower the dimensions as well as the target.
If the application requests a PDF rather than an image of the document, use Image to PDF Converter.
How to use it
- 1Upload your scan or document photo.
- 2The target is preset to 200 KB — change it to whatever the portal actually allows.
- 3Run the tool and read the measured output size in the result panel.
- 4Zoom into the preview to check the text is still readable, then download. If it looks mushy, raise the target and run it again.
Frequently asked questions
How small can I go before the text becomes unreadable?
For a typical A4 scan, 150–250 KB usually keeps body text sharp. Below about 100 KB, lossy compression starts to smear the edges of small characters. Text suffers from compression earlier than photographs do, so be more conservative here than you would be with a holiday snap.
Would resizing help more than compressing?
Often, yes. A scan photographed at 12 megapixels has far more resolution than the document needs. Reducing the width to around 1600–2000 pixels usually holds the text crisp and cuts the file dramatically before any quality loss is required.
Should I convert the scan to grayscale?
If the document is genuinely black and white, grayscale removes colour noise from the paper and helps the encoder, often producing a smaller and cleaner file. Don't do it for documents where a coloured stamp or signature matters.
Can I compress a PDF here?
No. This tool accepts image files such as JPG, PNG and WebP. If your scan is a PDF, export the page as an image first, or use the scanning app's image output.
Is my document scan uploaded for compression?
No. The KB target is tested locally against generated image data, not by sending the scan to a server. The unsaved result exists in the current tab; save before refreshing. Operational analytics may include format and approximate megapixels, not document contents or names.
What happens to your file
Your photographed certificate, ID page or form scan is compressed inside this browser tab so sensitive paperwork never leaves your device. Temporary previews are wiped from memory when you refresh or close the tab, while downloaded files remain on disk. Analytics records only tool and format events, never your document contents or filename.
Strong compression can make small print on a scan hard to read.
Full details are in the Privacy Policy.
When not to use this
If the portal asks for a PDF, compressing the image is only half the job; place the result in the Image to PDF Converter afterwards.
Do not reduce a certificate so far that seals, signatures or small print become unreadable. A legible larger file is better than a rejected tiny one.