Image Resizer

Key takeaways

• Width-only or height-only keeps aspect ratio automatically
• Contain vs stretch when both sides are specified
• Optional re-encode to JPEG/WebP while resizing
• Canvas processing stays on your device

What does an image resizer do?

An image resizer changes pixel dimensions — for thumbnails, social crops, or lighter downloads — without uploading the file.

Set width, height, or both. With one side set, the other is computed to keep aspect ratio. With both set, “contain” fits inside the box without cropping; “stretch” forces exact pixels. Output can stay PNG or re-encode as JPEG/WebP.

Features

• Aspect-aware scaling

  Provide one side and the other follows proportionally.

• Contain or stretch

  Dual targets can fit inside a box or force exact pixels.

• Format on export

  Save as PNG, JPEG, or WebP after scaling.

• Private processing

  No upload — useful for screenshots and product shots.

How it works

1. 1

   Drop an image

   JPG, PNG, WebP, GIF, or BMP within the size limit.

2. 2

   Set target size

   Enter width, height, or both, plus fit mode.

3. 3

   Resize and download

   Preview dimensions in the status line, then save.

Example walkthroughs

• Blog width

  Scales a wide photo to 1600px while keeping aspect ratio.

  photo.jpg → width 1600 (height auto)

• Exact icon box

  Forces a square export when a store listing demands exact pixels.

  logo.png → 512×512 stretch

Use cases

• Social and OG images

  Produce common 1200×630 or square assets from larger masters.

• Thumbnails

  Create smaller previews without opening a desktop editor.

Code snippets

• Scale with aspect ratio

  js

  Width-only resize math matching this tool’s default behavior.

  const targetW = 800;
  const targetH = Math.round((bitmap.height / bitmap.width) * targetW);
  canvas.width = targetW;
  canvas.height = targetH;
  ctx.drawImage(bitmap, 0, 0, targetW, targetH);

Common errors

• Image looks squashed

  Cause: Stretch mode was used with mismatched aspect ratios.

  Fix: Switch to contain, or set only one side so aspect is preserved.

• Upscaled image looks soft

  Cause: Browsers cannot invent detail when enlarging.

  Fix: Start from a larger original, or accept that upscaling softens edges.

About Image Resizer

Image Resizer is a private dimension workspace for thumbnails, hero images, avatars, and email assets. Drop a file, enter a target width and/or height, choose whether dual targets should contain or stretch, pick an output format, and download. Scaling happens with the browser canvas — image bytes never leave the tab.

Search intent for “resize image online” usually means hitting a platform constraint: a 1200×630 OG image, a 512×512 app icon, or a max-width for a CMS. Setting one side and letting aspect ratio fill the other is the safest default; stretch is available when a template demands exact pixels and you accept distortion.

Resizing is often the highest-leverage size reduction for photos. A 6000×4000 camera shot at high JPEG quality still weighs megabytes; scaling to 1600px wide for a blog can cut weight more than quality alone. Pair with Image Compressor when you need both fewer pixels and a lower encode quality.

Limits are explicit: very large megapixel images are rejected to protect browser memory, and GIF animations flatten to one frame on export. Transparency survives when you output PNG or WebP; JPEG drops alpha.

Best practice: resize to the largest size you will actually display (2× for retina if needed), then compress. Upscaling soft images rarely recovers detail — start from the highest-resolution original you have.

Frequently asked questions

Explore more

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• Privacy

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