TIFF vs PNG vs BMP: Lossless Image Format Comparison
What These Three Formats Actually Have in Common
TIFF, PNG, and BMP are all capable of storing image data without throwing any of it away. That single shared trait — lossless fidelity — is where the similarity largely ends. Each format was built for a different era, a different industry, and a different set of trade-offs. TIFF (Tagged Image File Format) was standardized by Aldus Corporation in 1986, primarily for desktop publishing and professional scanning workflows. PNG (Portable Network Graphics) arrived in 1996 as a patent-free answer to GIF, designed explicitly for the web. BMP (Bitmap) is a Microsoft format baked into Windows since version 1.0, and it has barely changed since the early 1990s. Understanding why each format was designed the way it was helps explain why a 24-megapixel RAW conversion might land at 68 MB as a TIFF, 22 MB as a PNG, and 69 MB as a BMP — and why that size difference does not automatically mean one format is better than another. The right choice depends entirely on where the file needs to go and what software needs to open it.
Compression: How Each Format Handles File Size
BMP applies no compression at all by default. A 4000 × 3000 pixel image at 24-bit color depth will consume exactly 4000 × 3000 × 3 bytes = 34.3 MB on disk, every time, regardless of image content. There is technically a run-length encoding (RLE) option in the BMP specification, but almost no software writes it, and several applications refuse to read it. Treat BMP as uncompressed storage. PNG uses DEFLATE compression — the same algorithm behind ZIP files — applied after a filtering step that tries to make pixel data more compressible. The compression level is adjustable from 0 (store only, no compression) to 9 (maximum compression, slowest). In Photoshop, you set this under File → Export → Export As → PNG, where the Quality slider maps inversely to DEFLATE level. A flat-color graphic like a logo might compress 80–90% relative to its raw pixel count. A photograph with fine grain or film noise might compress only 20–30%, because high-frequency detail resists DEFLATE well. PNG compression is always lossless — changing the level affects only speed and file size, never pixel accuracy. TIFF supports multiple compression schemes within the same format container: no compression, LZW, ZIP (DEFLATE), PackBits, and JPEG (which introduces lossy compression and should be avoided for archival work). LZW is the most universally compatible lossless option for TIFF. In Adobe Lightroom Classic, you select it under File → Export → Image Format: TIFF → Compression: LZW. LZW typically produces files 10–40% smaller than uncompressed TIFF, but still noticeably larger than PNG for most photographic content, because PNG's pre-filtering stage gives DEFLATE a head start that LZW lacks.
Color Depth and Professional Features: Where TIFF Pulls Ahead
PNG supports bit depths of 1, 2, 4, 8, and 16 bits per channel. That 16-bit ceiling covers most photography and web work comfortably. TIFF, however, supports 8, 16, and 32 bits per channel (floating point), which matters for HDR compositing, scientific imaging, and any workflow that must survive multiple rounds of editing without accumulated rounding errors. A 32-bit float TIFF can store values outside the 0–1 range, preserving highlight and shadow detail that 16-bit formats simply clip. TIFF also supports CMYK color mode natively, which PNG does not. If you are preparing files for offset printing — say, a magazine spread where the print shop expects CMYK TIFFs at 300 PPI — PNG is not a viable substitute. Similarly, TIFF handles multi-page documents and image sequences in a single file, a feature used heavily in medical imaging (DICOM-adjacent workflows), fax transmission, and GIS raster data. You can store a 50-page scanned document as one multi-page TIFF; PNG cannot do this without an external container. BMP is locked at 1, 4, 8, 16, or 24-bit color with an optional 32-bit mode that includes an alpha channel. It has no CMYK support, no floating-point option, and no multi-page capability. For professional color work, BMP is effectively a dead end. Transparency support also differs meaningfully. PNG handles alpha channels at both 8-bit and 16-bit precision, making it the standard choice for web graphics that need transparent backgrounds. TIFF supports alpha channels too, including pre-multiplied and straight alpha variants. BMP's 32-bit mode includes an alpha channel, but browser and application support for BMP transparency is inconsistent enough that you should not rely on it.
Real-World Use Cases: Matching Format to Workflow
For web delivery, PNG wins without much contest. Browsers have supported PNG since 1996, the alpha channel works reliably across every modern browser, and the file sizes are manageable. A UI icon set, a product image with a transparent background, a chart exported from a data visualization tool — these all belong in PNG. TIFF files served directly over HTTP are technically possible but wasteful; a 14 MB TIFF screenshot has no business on a web page when a 1.2 MB PNG of the same image is visually identical. For print and prepress, TIFF is the professional standard. Adobe InDesign, QuarkXPress, and most RIP (raster image processor) software expect TIFF for placed raster images. A CMYK TIFF at 300 PPI with LZW compression is a safe, predictable deliverable that will open correctly at a print shop running software from 2008 or 2024. For archival scanning and document preservation, TIFF is again the preferred format. The Library of Congress and most national archives specify uncompressed or LZW-compressed TIFF for digitization projects because the format is well-documented, widely supported, and not dependent on a single vendor's implementation. For software development and Windows system work, BMP still appears in specific contexts: Windows application resources, cursor and icon source files, and some legacy CAD and GIS tools that predate PNG support. If you are working in Visual Studio and need a splash screen bitmap, BMP is still a reasonable choice. Outside of those narrow contexts, there is little reason to create new BMP files. For photography editing workflows, TIFF at 16-bit with LZW compression is the standard interchange format between applications — for example, sending a file from Lightroom to Photoshop for retouching and back. PNG at 16-bit works too, but fewer applications write 16-bit PNG by default, and the interoperability is slightly less reliable across older software.
File Size Benchmarks: Numbers from Actual Test Images
To make the size comparison concrete, here are measurements from three test images converted to each format. All tests used uncompressed source data. 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 consistent: PNG edges out LZW-compressed TIFF by roughly 5–15% for photographic content, and by a larger margin for graphics-heavy or high-contrast content. Both compress dramatically better than BMP. For the document scan, PNG is nearly 12 times smaller than BMP — a difference that matters when you are archiving thousands of pages. One caveat: TIFF with ZIP (DEFLATE) compression rather than LZW will produce sizes very close to PNG, since both use the same underlying algorithm. If your TIFF workflow supports ZIP compression, the size gap between TIFF and PNG narrows considerably. Photoshop supports TIFF/ZIP; Lightroom Classic does not offer it as a direct export option.
Converting Between These Formats with CocoConvert
CocoConvert handles TIFF, PNG, and BMP conversion without requiring you to install Photoshop or ImageMagick. The most common conversion requests are TIFF to PNG (reducing file size for web or email delivery), BMP to PNG (modernizing legacy files), and PNG to TIFF (preparing web-sourced images for print workflows). For TIFF to PNG conversion, CocoConvert preserves the original bit depth where possible — a 16-bit TIFF will produce a 16-bit PNG rather than silently downgrading to 8-bit. If you need a specific bit depth, you can set it in the conversion options before processing. For BMP to TIFF or BMP to PNG, the process is straightforward since BMP is uncompressed. The output file will be smaller than the source in virtually every case. Honestly, there are things CocoConvert does not handle well. Multi-page TIFF files — the kind used for scanned document batches — are currently split into individual images rather than preserved as a multi-page container. If you need to keep a 50-page TIFF intact, a tool like ImageMagick (`convert input.tif output.tif` with the `-adjoin` flag) or Adobe Acrobat is a better choice. CocoConvert also does not convert TIFF files that use JPEG compression internally; those will return an error rather than a corrupted output. And for 32-bit floating-point TIFF files used in HDR or scientific workflows, the conversion to PNG will clip values outside the 0–1 range, because PNG has no floating-point mode. We flag this in the conversion preview rather than silently discarding data, but the limitation is real. For straightforward single-image conversions between these three formats — which covers the vast majority of use cases — upload your file, select the target format, and download the result. No account required for files under 20 MB.
Which Format Should You Actually Use?
There is no universally correct answer, but the decision tree is shorter than most format comparison articles suggest. Use PNG when: the file needs to go on the web, into a presentation, or into any application where file size matters and CMYK is not required. PNG is the safe default for anything that is not specifically a print or archival workflow. If you need transparency on the web, PNG is your only lossless option among these three. Use TIFF when: you are delivering to a print shop, archiving scanned documents, exchanging files between professional image editing applications, or working with CMYK color. TIFF with LZW compression is the right choice for any workflow where long-term compatibility and professional color fidelity matter more than file size. Use BMP when: the target application specifically requires it, you are working on Windows application resources, or you are dealing with legacy software that predates PNG support. In any other situation, PNG does everything BMP does and does it better — smaller files, transparency support, better compression, and wider compatibility outside the Windows ecosystem. One practical note: if you receive a BMP file from a client or legacy system, converting it to PNG immediately is almost always the right move. You lose nothing — BMP to PNG is lossless in both directions — and you gain a file that is typically 60–80% smaller and works in every context BMP works in, plus many more. The same logic applies to uncompressed TIFF files that do not need to stay in TIFF for workflow reasons: converting to PNG for storage or delivery saves space without sacrificing a single pixel of quality.