Image File Size Estimator
Estimate image file size by format and quality (JPEG, PNG, WebP, AVIF) from width and height, using typical bits-per-pixel figures.
Result
- Megapixels2.07 MP
- Assumed bits per pixel1 bpp
- Estimated size253 KiB (259 KB)
- Uncompressed reference (24-bit)5.93 MiB
- NoteLossy — quality setting applied
Step-by-step
- Pixels = 1920 × 1080 = 2,073,600 (2.07 MP).
- Estimated bytes = pixels × bits-per-pixel ÷ 8 = 2,073,600 × 1 ÷ 8 = 259,200 bytes.
- That is about 253 KiB. Actual size varies with image detail (±50%).
How to use this calculator
- Enter the image width and height in pixels.
- Choose the file format (JPEG, WebP, AVIF, PNG, or uncompressed BMP).
- For lossy formats, pick a quality level.
- Read the estimated file size and the assumed bits-per-pixel; expect ±50% versus real files.
About this calculator
How big will an image file be? It depends on the pixel dimensions, the file format, and — for lossy formats — the quality setting. This tool estimates file size from a typical bits-per-pixel figure for photographic content: it multiplies the pixel count by the bits each pixel consumes on average, then converts to bytes. JPEG, WebP, and AVIF are lossy formats that trade detail for size, with AVIF the most efficient and JPEG the least; WebP typically saves about 25–35% over JPEG and AVIF around 50%, at comparable quality. PNG is lossless and best for graphics, screenshots, and images with sharp edges or transparency, but it produces large files for detailed photos. BMP is fully uncompressed. Because real file size depends heavily on image content, treat these numbers as a typical-photo ballpark rather than an exact figure.
How it works — the formula
Bytes ≈ Width × Height × bits-per-pixel ÷ 8
Uncompressed (24-bit) = Width × Height × 3 bytesFile size scales with pixel count and the per-pixel bit budget the format/quality implies. Lossless and uncompressed formats use fixed high per-pixel costs; lossy formats use much lower, quality-dependent figures.
Worked examples
- Inputs:
- width=1920, height=1080, format=jpeg, quality=medium
- Output:
- ≈ 253 KiB
- Inputs:
- width=4000, height=3000, format=jpeg, quality=high
- Output:
- ≈ 2.86 MiB
- Inputs:
- width=1920, height=1080, format=avif, quality=medium
- Output:
- ≈ 127 KiB
Limitations
- Bits-per-pixel figures assume photographic content; graphics differ greatly.
- PNG size is highly content-dependent — the estimate is a rough upper-mid guess.
- Does not model metadata (EXIF), thumbnails, or alpha channels precisely.
A planning estimate (±50%). For exact sizes, encode the actual image — see the JPEG quality optimizer tool.