Why is my PNG so much bigger than a similar JPG?

PNG uses lossless compression, which preserves every detail but produces larger files for photos. JPG discards some detail specifically to shrink file size, which is why photos are usually smaller as JPG.

Should I compress or resize first?

Compression is usually enough for moderate limits. For strict limits or very high-resolution originals, resizing the pixel dimensions first often has a bigger impact on file size.

Will this work for a batch of images, not just one?

Yes, use Batch Image Converter to apply the same format change across multiple images in one pass instead of repeating the process for each file.

Image Tips

How to Shrink Images to Fit a Website's Upload Limit

📅 August 29, 2026 · 3 min read · ✍️ LovePDFImg Team

"File exceeds maximum upload size" is one of those errors that tells you there's a problem without telling you how big a problem. Here's how to actually get under whatever limit you're up against.

Check the Format First

Before compressing anything, it's worth knowing what format your image actually is - a PNG screenshot, for instance, is often 3-5x larger than the same image saved as JPG or WebP, purely because of how each format compresses. If you're not sure, Image Format Detector confirms it, and switching formats alone sometimes solves the size problem before you even touch a quality slider.

Compressing to a Target

Once you know the format, use the matching compression tool - Compress JPG, Compress PNG, or Compress WebP - and adjust the quality slider while watching the estimated output size. Most upload limits (2MB, 5MB, 10MB) are comfortably reachable without a visible quality drop, especially for photos, which have the most compression headroom.

👉 Start with: Compress JPG or Compress PNG - pick the one matching your file's actual format.

If the Image Is Still Too Big

Some limits are strict enough that quality compression alone won't get there - particularly with very high-resolution photos straight from a camera. In that case, Resize Image reduces the actual pixel dimensions first, which often has a bigger effect on file size than compression alone, since fewer pixels means less data regardless of quality setting.

Uploading Several Images at Once

If you're hitting the same limit on a batch of images rather than just one, Batch Image Converter handles format conversion across all of them in one pass, so you're not repeating the same fix file by file.

Double-Check Before Re-Uploading

After compressing, it's worth a quick look with Image Size Checker to confirm the actual file size before trying the upload again - saves a second failed attempt if the compression didn't go quite far enough the first time.