Image Resizer

Online Image Resizer

Resize images by exact dimensions, percentage, longest side, or social-media preset. Batch up to 20 images at once — everything runs in your browser.

No. Resizing happens entirely in your browser using the Canvas API. Your images never leave your device — you can disconnect the network after the page loads and the tool still works.

Input: JPG, PNG, WebP, GIF (first frame only) and BMP. Output: JPG, PNG, WebP, or keep the original. GIF and BMP outputs are converted to PNG.

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Up to 20 images, 30 MB each

Drop images here, or click to browse

Supported: JPG, PNG, WebP, GIF, BMP — up to 20 images at once

Why iKit Image Resizer

Fast, private, browser-only — resize a batch of images and download them in one click.

Four resize modes

Pick exact dimensions, a percentage, a longest-side limit, or a social-media preset.

Batch up to 20 images

Drop a whole folder. Single output downloads directly; multiple come bundled in a ZIP.

Privacy by design

Everything runs in your browser using Canvas. No image is ever uploaded — turn off the network and it still works.

Format conversion

Output as JPEG, PNG, WebP, or keep the original format. Adjustable JPEG / WebP quality.

Social media presets

One click for Instagram square / portrait / story, OG image, X header, YouTube thumbnail, LinkedIn banner, and more.

Aspect-ratio aware

Lock the ratio while typing dimensions, or choose a preset and we letterbox with a background colour you pick.

How the image resizer works

Four resize modes, 16 social presets, all powered by browser-native canvas.

  1. 1

    Choose a resize mode

    Pick exact dimensions (1080 × 1080), a percentage (50%), a longest-side cap (2048 px max edge), or a social-media preset (Instagram square, OG image, YouTube thumbnail, X header, etc.). Each mode handles edge cases differently — letterboxing, aspect-ratio locking, or stretch.

  2. 2

    Decode and resample

    createImageBitmap decodes the source. OffscreenCanvas handles the resampling using bilinear filtering for downscale and bicubic for upscale (browser-implemented). High-quality smoothing is enabled by default to avoid the "crunchy" look of nearest-neighbour shrinking.

  3. 3

    Optional letterbox or background fill

    When the target aspect ratio doesn't match the source, you can either crop, stretch, or letterbox with a chosen background colour. Letterboxing is recommended for social media presets — fills with brand colour, keeps the original framing intact.

  4. 4

    Output JPEG / PNG / WebP

    Choose the output format and quality (for lossy formats). Single image downloads directly; batches of multiple images bundle into a ZIP using the same pure-JS encoder as our image compressor.

Real social-media workflows

One source image, multiple platforms, in 30 seconds.

Cross-posting product shots

Drop one master shot, generate Instagram square (1080 × 1080), OG image (1200 × 630), and X header (1500 × 500) in one batch. Each preset crops or letterboxes correctly so the subject stays visible.

OG image generation for blog posts

Quickly resize a hero image to exactly 1200 × 630 — the size every social platform expects for link previews. Save as WebP for smaller file size with no visible quality loss.

Avatar / profile picture

Resize a square avatar to 400 × 400 (small) or 800 × 800 (large) — exactly the sizes Discord, Slack, and GitHub want. JPEG quality 90 keeps the file under 100 KB.

Bulk down-sizing for email

50 photos at original 12-megapixel resolution → 50 photos at 1920-px longest side, packaged as a single ZIP. The ZIP fits comfortably in any email provider's limit.

Why resize privacy matters

Resizing a personal photo to share online still involves uploading the unmodified original to most resize sites. iKit performs the resize in your browser using OffscreenCanvas, so the original bytes — full resolution, full EXIF — never leave your device. Only the resized output exists, and only on your machine.

  • Original file never uploaded — verifiable in DevTools Network tab.
  • EXIF metadata stripped during re-encoding for added privacy.
  • Single image direct download; multi-image ZIP packaged in-browser.

Related guides

Deep-dive tutorials and tool comparisons from the iKit blog.

Frequently Asked Questions

Are my images uploaded anywhere?

No. Resizing happens entirely in your browser using the Canvas API. Your images never leave your device — you can disconnect the network after the page loads and the tool still works.

Which formats are supported?

Input: JPG, PNG, WebP, GIF (first frame only) and BMP. Output: JPG, PNG, WebP, or keep the original. GIF and BMP outputs are converted to PNG.

What's the difference between the four resize modes?

Dimensions = an exact width × height. Percentage = scale by a percent of the original. Longest side = cap the long edge (handy for thumbnails). Preset = pick a known social-media size.

How many images can I process at once?

Up to 20 images per batch, 30 MB each. Single image downloads as a file directly; multiple images are bundled into a single ZIP.

Why does my JPEG look blurry after resize?

Browsers use bilinear sampling. For best results when shrinking dramatically, increase JPEG / WebP quality to 90+. To upscale a small image, no software (browser or otherwise) can recover detail that isn't in the source.