Convert color PDFs to grayscale or pure black & white with 7 algorithms
WhiskFile Convert PDF to Grayscale is a free online tool to convert color PDFs to grayscale or pure black & white with 7 algorithms. Files are processed entirely in your browser — nothing is uploaded to any server.
Quick Answer
Convert color PDFs to grayscale or pure black & white with 7 algorithms. WhiskFile's Convert PDF to Grayscale is free, works in your browser, and requires no account. Your files never leave your device — all processing happens locally.
Upload your PDF
Drag and drop or click to select a color PDF file. The tool loads it entirely in your browser — nothing is uploaded to any server.
Choose algorithm and mode
Pick a grayscale algorithm (Luminosity, Luma, Average, Lightness, or RGB channel). Switch between Grayscale (256 shades) and B&W (pure black/white with threshold) modes.
Adjust brightness and contrast
Fine-tune the output with brightness (-100 to +100) and contrast (-100 to +100) sliders. The live side-by-side preview shows original vs converted in real time.
Select pages
Convert all pages, even/odd only, or enter a custom range (e.g., 1-5, 8, 10-12). Unselected pages keep their full color in the output.
Choose output DPI
Select resolution quality: 96 (fast/small), 150 (balanced), 200 (good), or 300 (print quality). Higher DPI means better quality but larger file size.
Convert and download
Click Convert. View the ink savings estimate and file size reduction, then download your optimized grayscale or black & white PDF.
Max file size: 50 MB (free) · 500 MB (paid). Processing time: ~10s on average. Upload one file at a time.
Convert PDF to Grayscale runs entirely in your browser — no software to install. Works on any device with a modern browser.
Windows & Mac
Chrome, Firefox, Edge, Safari
iPhone & Android
Safari, Chrome mobile
iPad & Tablets
Full touch support
Unlike server-based tools that upload your documents, WhiskFile processes everything locally in your browser. Your files never leave your device — not even temporarily.
No upload required
Files are processed in your browser — nothing is sent to any server
100% private
No server storage, no data collection, no third-party access
Works offline
Once loaded, works without an internet connection
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Real Estate Agent
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Client-side processing
This tool now runs entirely in your browser — files never leave your device.
Result preview & sharing
Preview your processed file before downloading, and share results via a secure link.
Yes — color images take more bytes than grayscale. Typical size reduction is 10-40%, shown after conversion.
No. Color information is permanently removed. Keep a copy of the original if you need the color version.
Yes. Choose all, even, odd, or enter a custom range like '1-5, 8, 10-12'. Unselected pages stay in full color.
Grayscale preserves smooth tonal gradients (256 shades). B&W converts everything to pure black or pure white using an adjustable threshold — ideal for text-heavy documents and faxing.
Luminosity (BT.601) is the default and best for most documents — it matches how human eyes perceive brightness. Luma (BT.709) is the modern HDTV standard. Average gives equal weight to all channels.
Grayscale typically saves ~45% ink compared to color. Pure B&W mode can save up to ~70% since it eliminates all gray tones.
No. Everything runs 100% in your browser using client-side JavaScript. Your file never leaves your device.
200 DPI (default) is ideal for most documents. Use 300 DPI for high-quality print output, or 96-150 DPI for screen-only viewing with smaller file size.
The brightness slider (-100 to +100) lightens or darkens the entire output. Increase brightness to make dark scans more readable, or decrease it for a darker, more contrast-rich result. The preview updates in real time as you adjust.
The contrast slider (-100 to +100) controls the tonal range. Increasing contrast makes darks darker and lights lighter, enhancing text readability. Decreasing contrast creates a softer, more uniform look.
Yes. Upload your scanned PDF, switch to B&W mode, and adjust the threshold slider. A lower threshold makes more pixels black (darker output), while a higher threshold keeps more white. Use the preview to find the optimal setting.
Red, Green, and Blue channel modes extract a single color channel as grayscale. This is useful for analyzing color separations, removing colored backgrounds, or isolating text printed in a specific color.
Yes. Convert PDF to Grayscale is completely free with no signup, no task limits, and no watermarks. There are no file size or page count restrictions. Everything runs in your browser.
Yes. If you're looking to invert PDF colours (remove or desaturate color), this tool converts your color PDF to grayscale or pure black & white. Choose Grayscale mode for a natural desaturation, or B&W mode for a high-contrast inverted-colour look. Adjust brightness and contrast sliders to fine-tune the result.
Yes. Convert PDF to Grayscale runs entirely in your browser using WebAssembly. Your files are never uploaded to any server — they stay on your device throughout the entire process. No data is transmitted, stored, or accessible to WhiskFile or any third party.
Yes. Convert PDF to Grayscale works on any device with a modern browser — iPhone, Android, iPad, tablets, Chromebooks, and desktop computers. No app download required. The interface adapts to your screen size automatically.
Convert PDF to Grayscale accepts PDF files as input and produces PDF output. The maximum file size is 50 MB on the free plan (500 MB for Pro users). There are no page count limits.
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