Upload a PDF to preview and compress it.
Use this free Compress PDF Online tool to create a PDF at the exact file size you enter. It can reduce a large PDF for email, forms and uploads or increase a smaller PDF when a portal requires a specific size. Enter the target in KB or MB, preview the first page and download the finished file.
For a smaller target, choose Light, Balanced, Strong or Maximum compression and keep color or use grayscale. The tool tries progressively stronger settings until it can reach the target, then safely pads the result to the exact requested byte size. For a larger target, the original PDF data and visual quality are preserved while non-visible PDF padding is added.
How to Compress a PDF to an Exact Size
- Choose or drag and drop a PDF file up to 100 MB.
- Wait for the tool to read the page count and show the first-page preview.
- Enter the exact target size and choose KB or MB.
- For a smaller target, select Light, Balanced, Strong or Maximum compression.
- Keep Color or choose Grayscale to help reach a very small target.
- Edit the download file name if needed.
- Press Compress to Exact Size or Increase to Exact Size.
- Review the original size, target size, new size and first-page preview.
- Press Download PDF to save the exact-size document.
Compress or Increase PDF Size in KB and MB
If the target is smaller than the uploaded file, the PDF compressor rebuilds the pages using optimized images. If the target is larger, the tool keeps the original PDF and adds valid, non-visible padding in the trailer area before the final startxref section. A target equal to the original size creates an exact copy.
The size calculation uses binary units: 1 KB equals 1,024 bytes and 1 MB equals 1,048,576 bytes. For example, a target of 500 KB produces a file of exactly 512,000 bytes. The tool does not offer an approximate download: if a smaller target cannot be achieved, it asks you to choose a larger target or grayscale mode.
Choose the Best PDF Compression Level
Light compression
Light compression uses a higher page resolution and image quality. It is useful when small text, diagrams and photographs must stay clearer and the source PDF only needs a moderate size reduction.
Balanced compression
Balanced is the recommended default for everyday PDFs. It provides a practical mix of readable pages and smaller output size for email attachments, online forms, class notes and scanned documents.
Strong and maximum compression
Strong compression lowers page resolution and image quality to produce a smaller PDF. Maximum compression is designed for strict file-size limits where download size matters more than fine visual detail.
Color and Grayscale PDF Compression
Color mode keeps the visible page colors. Grayscale converts each rendered page to shades of gray and can reduce the size of colorful scans, reports and photo-heavy PDFs. Grayscale is especially useful for black-and-white documents that were originally scanned in color.
How Browser PDF Compression Works
For reduction, the tool renders each PDF page, optimizes it as a compressed image and builds a new PDF with the same page dimensions and order. This method can substantially reduce scanned and image-heavy documents. The selected compression level controls the rendered resolution and JPEG quality. Once the rebuilt PDF is below the target, standards-compatible padding brings it to the exact requested size.
How Increasing PDF Size Works
When you enter a target larger than the original file, the tool does not enlarge page images or reduce visual quality. It preserves the original PDF bytes and inserts non-visible comment padding in the safe trailer area before the final startxref section. This changes the file size without changing how the pages look.
When Should You Reduce PDF File Size?
- Compress a PDF for email attachment limits.
- Reduce a scanned PDF before uploading it to a portal.
- Create a smaller PDF for mobile download and sharing.
- Save cloud storage space used by image-heavy documents.
- Optimize reports, receipts, notes, forms and document scans.
- Make a PDF easier to send through messaging applications.
Frequently Asked Questions
How can I compress a PDF to an exact size?
Upload a PDF, enter the required KB or MB, choose compression settings and press Compress to Exact Size. The download is enabled only after an exact result is created.
Can this tool increase PDF file size?
Yes. Enter a target larger than the original. The tool preserves the original PDF and adds non-visible padding to reach the exact size.
Which compression level should I use?
Balanced is recommended for general use. Choose Light for clearer pages or Strong and Maximum for smaller targets.
Will PDF compression reduce quality?
A smaller target can reduce page resolution and image quality. Increasing the size preserves the original PDF quality.
Does the compressed PDF keep selectable text?
No. Smaller PDFs are rasterized, so the layout remains but text selection, search, links and forms are not preserved. Increasing size keeps the original file data.
Can I compress a scanned PDF?
Yes. Scanned and image-heavy PDFs often receive the largest size reduction.
Can grayscale make a PDF smaller?
Yes. Grayscale can help reach a smaller target when a document contains colorful pages or scans.
Are my PDF files uploaded to a server?
No. PDF reading, rendering, exact-size processing and download preparation happen locally in your browser.
What if my exact target is too small?
The tool will not provide an approximate file. Choose a larger target or try Grayscale so the rebuilt PDF can fit below the target.
Does 500 KB mean exactly 500 KB?
Yes. This tool uses 1 KB as 1,024 bytes, so 500 KB produces exactly 512,000 bytes.