Image File Size Calculator
Type a width and height, and a bit depth if it is not 24, to estimate roughly how large a file will be as JPEG, PNG or WebP, useful for planning before you even have the image. Or drop in a real file to see its exact dimensions and size.
Quick answer: Enter a width and height and the calculator shows the uncompressed size, the print size (at 300 DPI unless you change it) and estimates for JPEG at three quality levels, PNG and WebP. Drop in a real file instead to read its exact size, dimensions and bits per pixel.
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Most image formats up to 50 MB each
Your images never leave your device
Most image formats, up to 50 megabytes each Your images never leave your deviceHow to use the Image File Size Calculator
- Enter a width, height and bit depth, or drop in a real image.
- Read the estimated or exact file size for JPEG, PNG and WebP.
- Compare against your upload limit before you commit to a size.
Features
- Estimates uncompressed size plus JPEG high, medium and low quality estimates.
- PNG and WebP estimates alongside the JPEG figures.
- Print size shown at 300 DPI for the entered dimensions.
- Real file inspector: exact dimensions, bytes, bit depth and compression ratio.
How do I calculate an image's file size?
Multiply the width by the height by the bit depth, then divide by 8 to get the uncompressed size in bytes. A 1920 by 1080 image at the default 24 bits per pixel holds 2,073,600 pixels, so 2,073,600 x 24 / 8 is 6,220,800 bytes, which the tool shows as 5.93 MB. The compressed sizes are estimates built on that: JPEG is the pixel count times 3.0, 1.5 or 0.8 bits, for high, medium and low quality, divided by 8, PNG is 60 percent of the uncompressed size, and WebP is 70 percent of the medium JPEG figure. For the same image that gives 759 KB, 380 KB and 203 KB for JPEG, 3.56 MB for PNG and 266 KB for WebP. Treat them as planning figures, since a real file's size depends on what is in it.
How accurate are the estimates?
The estimates use standard bits per pixel assumptions for each format and quality level, so they are a useful planning figure rather than an exact prediction. A real photo's actual compressed size depends on its content: a busy, detailed image compresses less than a simple, flat one at the same settings.
What do the uncompressed and print size figures actually mean?
The uncompressed figure is what the image would weigh with no compression at all, one byte or more stored for every single pixel, which is the theoretical upper bound every compressed format is measured against. The print size figure translates the same pixel dimensions into inches at 300 DPI, the standard sharp print resolution, so you can see at a glance whether a given pixel size is actually large enough for the print size you have in mind before you commit to shooting or exporting at that resolution.
What is bits per pixel, and why does the inspector show it?
Bits per pixel is the real file's size in bits divided by its total pixel count, a single number that tells you how efficiently that specific file was compressed regardless of its dimensions. A very low figure, well under 1 bit per pixel, usually means heavy compression or a simple, flat source image; a high figure closer to 8 or more suggests light compression or a genuinely detailed photo. Comparing it against the uncompressed rate, shown as a multiple in the inspector, is a quick way to judge how much a specific file has already been compressed.
Frequently asked questions
Why would I need to estimate a file size before I have the file?
It helps when planning a photo shoot, a scan setting or an export size against a known upload limit, before you have generated the actual file to check.
What does the real file inspector show?
Drop in an actual image and it shows its exact width, height, byte size, bits per pixel and how that compares to what an uncompressed version would weigh.
Can I use this to pick a compression target?
Yes, once you see the estimate, use the Image Compressor or Image Size Reducer to hit that size on your real file.
Why are there three different JPEG estimates instead of one?
High, medium and low quality settings compress very differently, so a single JPEG number would be misleading. Seeing all three gives a realistic range for what your export settings are likely to produce.
Does the calculator account for image content, like a busy photo versus a plain graphic?
No, since it works from typed in dimensions alone with no actual image to analyse. It uses a general assumption for each format and quality level, which is why the real file inspector exists for an exact answer once you have an actual file to check.
Can I use this before deciding what resolution to scan a document at?
Yes, type the pixel dimensions a given scan resolution would produce and check the estimate against whatever size limit you are working within, before running the scan.
Guides for this tool
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