Image File Size Estimator
Instantly estimate how large an image will be in any format — no upload needed. Enter dimensions, color mode, and bit depth to see uncompressed and compressed file size estimates side by side.
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Quick Presets
Bitmap mode is always 1-bit.
dpi
Megapixels
Total Pixels
Channels
Bits/Pixel
Estimated File Sizes
JPEG does not support transparency. JPEG estimates use the non-alpha equivalent channel count.
Bitmap (1-bit) images only support black and white pixels.
CMYK is not supported by PNG, GIF, or WebP. Those estimates are approximate.
| Format | Est. Size |
|---|---|
| smallest largest |
Estimates are heuristic-based. Actual sizes vary with image content, encoder settings, and metadata.
Enter width and height to see file size estimates.
Print Reference at DPI
Width
Height
Print Size
Quality
Image Format Guide
Choosing the right format for your image depends on your use case. Here is a summary of when each format is appropriate.
| Format | Compression | Transparency | Best For |
|---|---|---|---|
| PNG | Lossless | Yes (alpha) | Screenshots, logos, illustrations, any image requiring exact pixel values |
| JPEG | Lossy | No | Photographs where some quality loss is acceptable; smallest web photos |
| WebP | Both | Yes | Web images; smaller than PNG or JPEG at equivalent quality |
| TIFF | Optional | Yes | Professional print workflows, archival storage, lossless editing master files |
| GIF | Lossless (8-bit) | 1-bit only | Simple animations and graphics with 256 or fewer colors |
| PSD | Minimal | Yes | GIMP/Photoshop working files with layers — not for delivery |
About Compression Ratios
The estimates above use simple heuristics:
- PNG — typically 40–70% of raw size for photos; less savings on gradients or already-compressed images.
- JPEG Q95 — ~10% of raw uncompressed size. Very high quality, minimal visible loss.
- JPEG Q75 — ~4% of raw size. Good web quality; some artifacts visible on close inspection.
- WebP lossless — ~20% of raw; generally beats PNG.
- WebP Q80 — ~3% of raw; comparable to JPEG Q75 but usually smaller.
- GIF — always 8-bit indexed (1 byte per pixel), so fixed regardless of bit depth setting.
- PSD — raw pixel data plus roughly 10% overhead for layer metadata.
Checking and Reducing File Size in GIMP
GIMP gives you direct control over all the factors that affect file size:
- Color mode — Image → Mode. Converting to Grayscale removes color channels; converting to Indexed reduces to 256 colors (like GIF).
- Bit depth — Image → Precision. 8-bit per channel is the standard for web; 16-bit or 32-bit is for HDR or professional editing.
- Export settings — Use File → Export As to choose format and compression. GIMP shows the estimated file size in the PNG and JPEG export dialogs.
- Flatten before JPEG — JPEG doesn't support layers or transparency. Use Image → Flatten Image before exporting to JPEG.
- Scale down — Image → Scale Image to reduce pixel dimensions, which has the biggest single impact on file size.