“Resize the image” hides three different operations: changing the dimensions in pixels, changing the file size in kilobytes, and changing the print size in inches. People ask for one and get another, which is how a client ends up with a 300 KB logo that’s 200 pixels wide, or a 4,000-pixel photo that’s “too big for the website” when the real problem was compression. This guide separates the three, gives the exact pixel sizes for the platforms that matter, explains what happens when you enlarge, and shows a workflow that keeps quality where it counts.
Pixels, kilobytes and inches
- Pixel dimensions (1920 × 1080) are the image’s actual resolution: how many dots of colour it contains. This is what “resize” means in this article and in the Image Resizer.
- File size (KB, MB) depends on pixel dimensions and compression and format. Shrinking pixels reduces it; so does compressing. Use the Image Compressor when the dimensions are already right and the file is still heavy.
- Print size (inches, cm) is pixels ÷ DPI. A 3,000-pixel-wide image prints at 10 inches at 300 DPI or 30 inches at 100 DPI. DPI is metadata; changing it doesn’t change the pixels.
The sizes that matter
| Use | Pixels | Ratio |
|---|---|---|
| Instagram feed post (square) | 1080 × 1080 | 1:1 |
| Instagram portrait | 1080 × 1350 | 4:5 |
| Instagram / TikTok / Reels / Stories | 1080 × 1920 | 9:16 |
| Facebook / LinkedIn / X link preview (OG image) | 1200 × 630 | 1.91:1 |
| YouTube thumbnail | 1280 × 720 | 16:9 |
| YouTube channel banner | 2560 × 1440 (safe area 1546 × 423) | 16:9 |
| LinkedIn profile photo | 400 × 400 | 1:1 |
| Website hero | 1920 × 1080 (or 2400 wide for retina) | 16:9 |
| Blog inline image | 1200–1600 wide | any |
| Email header | 600–1200 wide | 2:1 to 3:1 |
| Favicon | 512 × 512 (browser scales down) | 1:1 |
| Amazon product image | 2000 × 2000 (min 1000) | 1:1 |
| Etsy listing | 2000 × 1500 | 4:3 |
| Passport photo (digital, many countries) | 600 × 600 to 1200 × 1200 | 1:1 |
Platforms change specs; these are stable as of writing and the resizer has presets for them.
Downscaling: safe, with two caveats
Making an image smaller discards pixels, and done with a good algorithm (Lanczos or bicubic) the result is sharper than the original at the new size. Two things to watch:
- Aspect ratio. Lock it. Resizing 4000 × 3000 to 1080 × 1080 without cropping squashes the image. If the target ratio differs from the source, crop first, then resize. The resizer’s “fit” mode keeps the ratio and pads or letterboxes; “fill” mode crops to the ratio.
- Sharpening. Heavy downscaling (more than 50%) softens fine detail slightly. A light sharpen afterwards restores it. Most tools apply this automatically.
Upscaling: the honest limits
Enlarging an image cannot add detail that was never captured. Traditional interpolation (bicubic) spreads existing pixels and blurs; you can safely go to about 150% before it shows. AI upscalers (built into recent Photoshop, and services like Topaz) invent plausible detail and can go 2–4× on photos convincingly, but they hallucinate on text, faces at small sizes, and fine patterns. For logos and graphics, the real fix is to get the vector original (SVG, AI, EPS); a 200-pixel PNG logo has no good upscale.
Retina and responsive images
Modern phones and laptops have 2–3 device pixels per CSS pixel. An image displayed at 800 CSS pixels needs 1,600 real pixels to look sharp on those screens. So export at twice the display size, and let the browser choose with srcset: WordPress generates the smaller variants automatically as long as the upload is large enough. The trade-off is file size, which is where compression comes back in.
A workflow that keeps quality
- Keep the original at full resolution somewhere safe. Never overwrite it.
- Crop to the target ratio.
- Resize to the target pixels (2× the display size for web).
- Convert to WebP for web use with the Image Converter; keep JPG/PNG for platforms that require them.
- Compress to the size budget.
- Name the file descriptively and add alt text on upload.
For a set of images going to the same destination, the Bulk Image Resizer applies one size to all of them and returns a zip.
Frequently asked questions
Does resizing reduce image quality?
Making it smaller doesn’t, as long as the aspect ratio is preserved and a decent algorithm is used. Making it larger always does; the question is how visibly.
How do I resize an image without stretching it?
Lock the aspect ratio, and crop to the target ratio first if it differs from the source.
What size should images be for a website?
Twice their largest display width for retina screens: 1,600 px for an 800 px content column, 2,400 px for a full-width hero. Then compress to under ~150 KB.
What is the difference between resizing and compressing?
Resizing changes the pixel dimensions. Compressing changes how efficiently those pixels are stored. Both reduce file size; do the resize first.
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