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iSpeedIMG

Resize a PNG online

Set exact pixel dimensions for your PNG with the aspect ratio locked — or free — and keep the transparency. Output stays lossless PNG by default, so logos, screenshots and graphics stay pixel-exact; the whole job runs in your browser.

How to resize an image

  1. 1. Drop your image onto the tool or click to choose a file. Its current size is filled into the width and height fields.
  2. 2. Type the width or height you need. With aspect lock on, the other value follows automatically and the preview updates as you type.
  3. 3. Hit Download. The resized image is saved straight from your browser.

Supported formats

Format Open as input Save as output Good to know
JPG / JPEG Yes Yes Universal compatibility. No transparency (flat areas become white).
PNG Yes Yes — Auto keeps PNG Lossless when kept as PNG. Transparency kept.
WebP Yes Yes Usually the smallest files; transparency kept.
AVIF Yes (recent browsers) Saved as WebP Browsers decode AVIF but can't encode it yet — details in the compatibility section below.

Settings explained

Width & height (pixels)
The exact dimensions of the output. Values up to 16384 px per side are accepted.
Lock aspect ratio
On: changing one value rescales the other by the image's original proportions, so nothing is stretched. Off: both values are independent — useful when a platform demands exact, non-proportional dimensions.
Output format
Auto keeps the original format. Choosing JPEG or WebP re-encodes regardless of input.
Quality (1–100%)
Applies to JPEG and WebP output. PNG is lossless, so the slider is ignored for it.

Output behavior

  • The output has exactly the dimensions you entered — with lock on, always in the original proportions.
  • Even with Auto and unchanged dimensions, the image is re-encoded, so the file size changes and metadata is not carried over.
  • EXIF, GPS and camera metadata are stripped from the output.
  • Transparency is preserved in PNG and WebP output; JPEG flattens it to white.
  • Upscaling is allowed but the tool says so plainly: enlarged output cannot regain detail.

Real resizing results

Measured by saving the same 1600×1000 test image at each width as JPEG quality 90, so the difference comes from the dimensions alone. Your files will differ — the ratios are what matter.

Dimensions File size vs. original
Original — 1600 × 1000 91 KB —
Resized to 1600 × 1000 91 KB 0% larger
Resized to 1200 × 750 69 KB 24% smaller
Resized to 800 × 500 38 KB 59% smaller
Resized to 400 × 250 14 KB 85% smaller

Privacy

This tool works completely offline in your browser. Your image is read into memory, rescaled and re-encoded locally, and offered back to you as a download. Nothing is transmitted to any server, and closing the tab discards everything.

Browser & device compatibility

  • JPG, PNG and WebP work in every modern browser.
  • AVIF input needs a recent browser — current Chrome, Edge, Firefox or Safari 16+. On older browsers you'll see a clear message instead of a broken result.
  • Very large images can exceed the memory of older phones and tablets — processing happens on your device, so your hardware sets the ceiling.

Troubleshooting

  • "That file type isn't supported" — the file isn't a JPG, PNG, WebP or AVIF image. Rename or re-export it first.
  • "Your browser couldn't decode this file" — the type is recognized but this browser can't read it (often AVIF on an older browser), or the file is corrupted.
  • Enlarged image looks soft — that's upscaling: pixels can't be recreated. Resize from the largest original you have.
  • The field refuses a value — dimensions are capped at 16384 px per side, a limit browsers impose on canvas processing.

Related tools

  • Compress Image — Reduce JPG, PNG and WebP file size with quality you control.
  • Convert Image — Convert between JPG, PNG, WebP and AVIF without uploading a thing.
  • Crop Image — Trim to the perfect frame or a preset aspect ratio.

Frequently asked questions

How do I resize an image to exact dimensions?

Drop your image, type the width or height you need — the other value follows automatically while aspect lock is on — then download. The preview shows the exact result before you save it.

Does resizing reduce image quality?

Downscaling (making an image smaller) discards pixels, so some detail is permanently removed — but at typical sizes the result still looks sharp. Upscaling cannot create detail that was never captured, so enlarged images look soft. The tool warns you when an output would be upscaled.

Will the file size get smaller too?

Almost always, because file size scales with pixel count. The measured table below shows the same test image saved at several widths. Re-encoding also strips metadata, which reduces the size further.

Can I resize photos for social media and profile pictures?

Yes — type the dimensions you need (Instagram posts 1080×1080, YouTube thumbnails 1280×720, WhatsApp profile pictures, and so on), keep the aspect ratio locked so nothing stretches, and check the preview before downloading.

What does "Lock aspect ratio" do?

It preserves the proportions of your image. Change the width and the height adjusts automatically — and vice versa — so the picture is never stretched. Turn it off to set width and height independently.

Are my images uploaded to a server?

No. Resizing runs entirely in your browser on your device's own processor. Your images never leave your computer or phone.

How do I resize a PNG?

Drop the PNG in, enter the width or height you need — the other value follows for as long as the aspect lock is on — then download. The output is a PNG again unless you deliberately switch the format, so transparency and sharp edges survive.

Does resizing a PNG lose quality?

Making a PNG smaller discards pixels — that is what resizing means — and enlarging cannot invent detail that was never there, so big upscales go soft. What the resize never does is add compression artifacts: PNG output is lossless, and your transparent areas stay transparent in PNG and WebP output.