Pixel Resolution Image Size Calculator
Computes megapixels and estimates raw file size in megabytes from image width, height and bits per pixel color depth value.
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Image size from resolution and bit depth
Uncompressed, an image weighs in at size_MB ≈ width · height · bits_per_pixel / 8 / 1024². Take a 24-bit 4K image (3840 × 2160): 3840 · 2160 · 24 / 8 / 1024² ≈ 23.7 MB with no compression. Real files are smaller because formats compress. PNG stays lossless and rides on how busy the image is. JPEG at quality 90 usually drops that same 4K to 5–10 MB. RAW from a DSLR or mirrorless body runs 25–40 MB at 14-bit. WebP and AVIF shave another 25–50% off JPEG at the same perceived quality. And bit depth scales everything: bump to 16-bit per channel and a 24-bit RGB file doubles.
Applications: cloud storage and page weight
Think about guessing how much iCloud or Google Photos your camera will eat through, budgeting CDN egress for an e-commerce gallery, picking JPEG over WebP (or the reverse) to keep your LCP fast, or sizing up a RAW backup routine on external SSDs.
FAQ
Why does my JPEG come out so much smaller than the formula? Because JPEG throws away detail your eye won't miss, that's what lossy compression does. The formula is the uncompressed/raw ceiling, not what you'll actually save.
24 or 32 bits per pixel? 24 bits is plain RGB, 8 per channel. 32 bits tacks on an 8-bit alpha channel, so reach for it only when you actually need transparency.
Does DPI affect file size? Not directly. DPI is just print metadata. The size only moves when the pixel dimensions or the bit depth change.
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The results provided by this tool are for general informational and educational purposes only and do not constitute professional, financial, medical, legal, tax or accounting advice. Always confirm important decisions with a qualified professional and official sources.