JPG Resizer — Resize JPG Images Online
Resize a JPG to exact pixel dimensions, or scale by percentage. Lock aspect ratio to avoid stretching. Outputs a fresh, optimised JPG.
Why resize a JPG?
The biggest reason to resize a JPG is page speed. A photograph straight from a phone camera is typically 4,000+ pixels wide; the spot it'll appear on your web page might be only 800. Serving the full-resolution image wastes bandwidth, slows page load and hurts Core Web Vitals — Google's ranking signal. Resizing the JPG down to the actual display size (or 2× for high-DPI screens) is the single biggest performance fix in web development.
Other reasons: hitting exact dimensions for social media (1080×1080 for Instagram, 1200×630 for Open Graph), shrinking for email attachments (most providers cap at 25 MB total), preparing for printing (DPI calculations), or simply because the file is bigger than your destination accepts.
How this resizer works
Your JPG is drawn onto a canvas at the new target dimensions using high-quality bicubic-style resampling. The result is re-encoded as JPG at the quality you choose. Everything happens locally — no upload, no server, no queue.
Two ways to set the size:
- Exact pixel dimensions — type width and height. With "Lock aspect" ticked, editing one dimension updates the other automatically.
- Percentage scale — drag the slider. 50% halves dimensions, 200% doubles them.
Common target sizes for resizing JPG
| Use case | Recommended size |
|---|---|
| Hero image (desktop) | 1920 × 1080 |
| Hero image (mobile) | 1080 × 1350 |
| Open Graph preview | 1200 × 630 |
| Twitter card | 1200 × 628 |
| Instagram post (square) | 1080 × 1080 |
| Instagram story | 1080 × 1920 |
| YouTube thumbnail | 1280 × 720 |
| LinkedIn cover photo | 1584 × 396 |
| Email signature image | 400 × 150 (or smaller) |
| Profile avatar | 400 × 400 |
Aspect ratio — keep it locked
"Lock aspect" prevents stretching. Edit one dimension and the other auto-updates to keep the image proportional. Unlocking lets you freely deform the image — useful for banners with specific dimensions, but rarely flattering for photos.
Upscaling vs. downscaling
Downscaling (making smaller) almost always looks fine — the algorithm has more source pixels to average than output pixels, so detail is preserved. Upscaling (making larger) can't add detail that wasn't there; modest upscales (up to 2×) look acceptable, beyond that the image gets soft. For dramatic upscales, AI super-resolution tools outperform conventional resampling.
Tips and best practice
- For high-DPI screens (Retina), serve images at 2× display size. A 400×400 avatar should be 800×800.
- Combine resize with the JPG Compressor for the smallest possible web-ready files.
- For printing, work backwards from DPI: an image to print at 4 inches at 300 DPI needs to be 1200 pixels wide.
- Pick quality 85–90 for the resized output — that's the sweet spot for hero-image quality without bloating the file.
- Resize then save once — re-saving JPGs progressively damages quality.
FAQs
Will the JPG quality drop?
Re-saving JPG always introduces some loss. Pick quality 88+ to keep it imperceptible on photographs.
How do I avoid stretching?
Keep "Lock aspect" ticked. Editing one dimension auto-updates the other.
Is anything uploaded?
No. Resizing runs in your browser.
Can I resize multiple JPGs at once?
Not yet — one at a time.
What's the maximum output size?
20,000 × 20,000 in theory. Browser memory is the practical limit (usually 8K is safe on desktop).