KissPDF Free Online PDF Compressor
Reduce PDF file size for email, online forms, sharing, or storage. Compress a PDF to 100KB, 200KB, 300KB, 400KB, 500KB, or enter any custom KB or MB target.
A smaller PDF is easier to attach to email, submit through online forms, upload, and store.
KissPDF processes the complete PDF in browser memory instead of sending it to a document-processing server.
Compress a PDF locally in four steps.
Drop one PDF into the page or select it from your device.
Select a quality level or enter a target size such as 200 KB or 1 MB.
Start compression and keep the tab open while the file is processed locally.
Review the original and result sizes, then download the compressed PDF.
Practical guide
Reduce PDF file size with a quality preset or compress a PDF to 50 KB, 100 KB, 200 KB, 300 KB, 400 KB, 500 KB, 1 MB, 2 MB, 5 MB, or any custom target. KissPDF first tries structure-preserving compression, then uses strict page flattening only when necessary and returns the highest-quality tested result that fits the requested limit.
Balanced is the recommended starting point for email and everyday sharing. High quality retains more image detail for printing. Maximum compression creates the smallest preset result. Target file size searches for the best-quality PDF that fits a specific KB or MB upload limit.
PDF compression can reduce file size by downsampling images and rewriting eligible document objects. Image-heavy scans usually offer the largest savings. In target mode, KissPDF measures each final candidate and keeps the highest-quality tested result below the limit. Some unusually long or complex PDFs can still remain above very small targets.
The compressor runs in a dedicated Web Worker so the interface remains responsive. In our July 2026 repeatable test, Balanced mode reduced a 4.15 MB image-heavy one-page fixture to about 500 KB. This is one test sample, not a promised compression ratio. Compression rewrites the PDF, so signatures and some advanced interactive features may change.
Clear answers based on how this tool actually works.
Select one PDF, choose a compression level, and start compression. When processing finishes, compare the original and result sizes before downloading the smaller document.
Yes. KissPDF compresses one PDF at a time without an account or watermark. The selected PDF bytes are processed locally in your browser rather than uploaded to a document-processing server.
Yes. Choose Target file size, select a common KB shortcut, or enter a custom upload limit. KissPDF returns the highest-quality tested PDF that does not exceed the target. If the limit is impossible, it returns the smallest candidate and clearly reports the best achievable size.
Select the PDF, choose Target file size, and select 200 KB. KissPDF tests progressively stronger settings and downloads the highest-quality candidate it finds at or below 200 KB.
No. Target-size compression reduces the downloaded file size and keeps the original PDF page dimensions. Use Resize PDF when you need to change physical page sizes such as A4 or Letter.
Start with Balanced. Use High quality for print-sensitive material and Maximum compression only when a smaller upload is more important than image detail.
Compression involves a tradeoff when images are downsampled. Ordinary text and vector artwork normally remain sharp, but image resolution and detail depend on the selected compression level.
It may already contain compressed images, few images, or mostly text and vectors. Rewriting those files adds little opportunity for further reduction.
Quality presets retain ordinary PDF text and vectors. Target mode tries those methods first, but may flatten pages into JPEG images when that is the only practical way to reach a strict size limit.
Yes. KissPDF runs in a compatible current browser, so no platform-specific PDF application is required. Current Chrome and Edge receive the most direct test coverage.
Not in the current version. The compressor processes one PDF per task so you can review its quality and file-size result before downloading.
No. The compression engine processes the selected PDF bytes locally in browser memory. The file is not uploaded to a document-processing server for compression.
No. Any operation that rewrites signed PDF bytes invalidates the existing signature. Compress an unsigned copy instead.