TIFF vs PNG vs BMP: Lossless Image Format Comparison
What These Three Formats Actually Have in Common
TIFF, PNG, and BMP all share one critical trait: they can store image data without throwing any of it away. But that shared promise of lossless fidelity is where the similarities stop. Each format was born in a different era, designed for a different industry, and built on a different set of compromises. TIFF (Tagged Image File Format) was created by Aldus in 1986 for the world of desktop publishing and professional scanning. PNG (Portable Network Graphics) showed up in 1996 as a patent-free replacement for GIF, built from the ground up for the web. And BMP (Bitmap)? That's a Microsoft original, baked into Windows since version 1.0 and barely touched since the early 90s. Their origins explain everything. It’s why a 24-megapixel RAW conversion can be 68 MB as a TIFF, 22 MB as a PNG, and a whopping 69 MB as a BMP. That size difference doesn't make one format inherently better; it just reflects their design goals. The right choice is always about where the file is going and what software needs to read it.
Compression: How Each Format Handles File Size
BMP is the simplest of the bunch: by default, it uses no compression at all. A 4000 × 3000 pixel image with 24-bit color will always take up exactly 4000 × 3000 × 3 bytes = 34.3 MB on disk. The content of the image doesn't matter. While the BMP spec technically includes a run-length encoding (RLE) option, it’s a ghost feature; almost no modern software writes it, and many applications can't even read it. For all practical purposes, just treat BMP as completely uncompressed storage. PNG uses the DEFLATE compression algorithm, the same workhorse found in ZIP files. Before compressing, PNG runs a filtering step to arrange pixel data in a way that makes it more compressible. You can adjust the compression level from 0 (no compression) to 9 (maximum effort, slowest speed). In Photoshop, this is the “Quality” slider under File → Export → Export As → PNG. The results vary wildly with image content. A logo with large flat areas might shrink by 80–90%, but a photograph with complex textures and film grain might only compress by 20–30%. High-frequency detail is simply hard for DEFLATE to handle. Crucially, PNG compression is always lossless. Changing the level only impacts file size and how long it takes to save, never the pixels themselves. TIFF is more of a flexible container, supporting multiple compression schemes. You can choose no compression, LZW, ZIP (DEFLATE), PackBits, or even JPEG (which is lossy and generally defeats the purpose of using TIFF for archival work). LZW is the most widely supported lossless option. In Adobe Lightroom Classic, you find it under File → Export → Image Format: TIFF → Compression: LZW. LZW usually creates files 10–40% smaller than an uncompressed TIFF. However, these files are still often larger than a comparable PNG, because PNG's smart pre-filtering gives its DEFLATE algorithm a significant advantage that LZW just doesn't have.
Color Depth and Professional Features: Where TIFF Pulls Ahead
For serious professional work, this is where TIFF pulls away from the pack. While PNG supports bit depths up to 16 bits per channel—which is plenty for most photography and web graphics—TIFF goes further. It handles 8, 16, and even 32-bit floating point channels. That 32-bit float support is critical for High Dynamic Range (HDR) composites, scientific imaging, and any workflow that involves multiple rounds of heavy editing. It prevents the gradual degradation from rounding errors that can happen with each save in a 16-bit format, and it can store brightness values far beyond what a normal screen can display. TIFF also speaks CMYK, the language of professional printing. PNG does not. If you are sending files to an offset printer for a magazine or book, they will almost certainly expect a CMYK TIFF at 300 PPI. A PNG is simply not a viable option in that world. Then there's the multi-page feature. Anyone who has wrangled a 50-page scanned document knows the pain of dealing with 50 individual files. TIFF can store all those pages in a single, tidy file, a feature heavily used in document archiving, medical imaging, and fax systems. PNG can't do this. And BMP? It's a non-starter. BMP is stuck with basic color modes (1, 4, 8, 16, or 24-bit, plus a 32-bit mode with alpha) and has no support for CMYK, floating-point data, or multiple pages. For professional color, it's a dead end. Transparency is another key difference. PNG is the undisputed champion for web use, with clean 8-bit and 16-bit alpha channel support. TIFF handles alpha channels too, with more complex options like pre-multiplied alpha, but it's overkill for the web. BMP's 32-bit mode technically includes an alpha channel, but support is so spotty across browsers and applications that relying on it is a gamble you shouldn't take.
Real-World Use Cases: Matching Format to Workflow
On the web, PNG is king. There's really no debate. Browsers have supported it since the late 90s, its alpha transparency works flawlessly everywhere, and its file sizes are lean. Every UI icon, product shot with a transparent background, or exported chart you see online is, or should be, a PNG. Serving a 14 MB TIFF screenshot on a webpage is malpractice when a visually identical 1.2 MB PNG exists. Step into a print shop, however, and TIFF is the currency. For prepress work, it's the professional standard. Applications like Adobe InDesign and QuarkXPress, along with the RIP (raster image processor) software at the printers, are built around TIFF. A CMYK TIFF with LZW compression is a bulletproof deliverable that works whether the print shop is running brand new software or something from 2008. This same rock-solid reliability makes TIFF the format of choice for archival and digitization projects. The Library of Congress and other national archives mandate uncompressed or LZW-compressed TIFF because the format is a well-documented open standard, not tied to a single company. So where does that leave BMP? It's a niche player, mostly hanging on in specific Windows-centric tasks. If you're building a Windows application in Visual Studio and need a splash screen, or dealing with legacy CAD tools, you'll still run into it. Outside of those narrow corridors, there's almost no reason to create a new BMP file today. In a photography editing pipeline—for instance, bouncing a file from Lightroom to Photoshop for retouching and back again—a 16-bit TIFF with LZW compression is the standard handshake. While a 16-bit PNG could also work, TIFF is more universally supported for this kind of high-bit-depth interchange, especially with older software.
File Size Benchmarks: Numbers from Actual Test Images
Theory is one thing, but the numbers tell the real story. We took three distinct images and converted them from uncompressed source data to each format. Test image 1: A 3840 × 2160 photograph of a forest (high detail, no flat areas). - BMP (24-bit, no compression): 23.7 MB - TIFF (LZW): 19.1 MB - PNG (DEFLATE level 6, default): 17.4 MB Test image 2: A 1920 × 1080 UI screenshot (large flat-color regions, text, icons). - BMP (24-bit): 5.9 MB - TIFF (LZW): 1.8 MB - PNG (DEFLATE level 6): 0.9 MB Test image 3: A 600 × 800 scanned document page (black text on white, minimal noise). - BMP (24-bit): 1.4 MB - TIFF (LZW): 0.18 MB - PNG (DEFLATE level 6): 0.12 MB The pattern is clear. For photographic content, PNG consistently beats LZW-compressed TIFF by about 5–15%. For graphics-heavy images or scanned documents with lots of flat color, PNG's advantage becomes massive. In the document scan, the PNG is nearly 12 times smaller than the BMP, a difference that adds up fast when you're archiving thousands of pages. There is one important caveat: a TIFF saved with ZIP (DEFLATE) compression will have a file size very close to a PNG, since they're using the same core algorithm. If your software supports TIFF/ZIP, the size difference effectively vanishes. Photoshop can do it, but Lightroom Classic, for example, doesn't offer it as a direct export option.
Converting Between These Formats with CocoConvert
You can use CocoConvert to move between TIFF, PNG, and BMP without needing to fire up Photoshop or a command-line tool. The most common jobs are converting TIFF to PNG to shrink files for the web, modernizing old BMPs into PNGs, and turning web-sourced PNGs into TIFFs for a print workflow. When you convert a TIFF to a PNG, CocoConvert works to preserve the original quality. A 16-bit TIFF becomes a 16-bit PNG, not a downgraded 8-bit file. You can also manually set the bit depth in the options if you need specific output. Moving from BMP to either TIFF or PNG is simple. Since BMP is uncompressed, the resulting file will almost always be significantly smaller than the original. It's also important to know what CocoConvert *doesn't* do. Multi-page TIFFs, like those from a document scanner, are currently split into separate images instead of being kept in a single multi-page file. For that, you're better off with a dedicated tool like ImageMagick (`convert input.tif output.tif` with the `-adjoin` flag) or Adobe Acrobat. CocoConvert will also throw an error on TIFFs that use internal JPEG compression, which is better than giving you a corrupted file. Finally, if you convert a 32-bit floating-point TIFF, the data will be clipped to fit within PNG's more limited range. We flag this during the conversion process so you aren't silently losing data, but it's a real limitation of the target format. For the vast majority of conversions—a single image from one format to another—the process is dead simple. Upload your file, pick your target, and download. No account needed for files under 20 MB.
Which Format Should You Actually Use?
After all that, the decision tree is much simpler than you might think. Here’s how to choose. Your default choice for anything destined for a screen should be PNG. If the file is going on the web, in a presentation, or in any app where file size and compatibility matter, use PNG. It's the modern, safe default for anything that isn't a specialized print or archival job. If you need transparency on the web, stop reading and just use a PNG. You should switch to TIFF when your work needs maximum fidelity for professional editing or is leaving the digital world for print. Use TIFF when you're delivering to a print shop, archiving critical scans, exchanging high-bit-depth files between pro photo apps, or working with CMYK color. TIFF with LZW compression is the workhorse for any workflow where long-term compatibility is more important than minimal file size. And BMP? You only use BMP when a specific, often ancient, piece of software forces your hand. It's a legacy format for Windows app resources and old programs that predate PNG. In any other scenario, PNG does everything BMP does but better, creating smaller files with wider support. Here’s a final, practical tip: if you ever receive a BMP, your first move should be to convert it to PNG. The conversion is perfectly lossless, and you'll get a file that's dramatically smaller and more useful everywhere. The same logic applies to giant, uncompressed TIFFs that don't need to stay in that format for a specific workflow reason. Convert to PNG to save space without sacrificing a single pixel of quality.