Resize Image

Using the Resizer, Step by Step

1. Add a picture. Drop a JPG, PNG, or WebP file on the box, or click it to pick a file. A preview appears, with the original size under it (for example, "Original: 4000 × 3000").
2. Type the new width or height in pixels. Both boxes start with the original numbers. With "Maintain aspect ratio" ticked, you only need to type one number. The other one updates as you type.
3. Untick the box only if you want a different shape. Then you can type both numbers freely, but the picture will be stretched or squashed to fit.
4. Click "Resize & Download". The file saves with resized_ in front of the original name, so your original is never overwritten. Click "Clear" to start again with another picture.

There is no percentage box. To scale by a percentage, multiply the width yourself. For 50% of a 4000 px wide photo, type 2000. For 25%, type 1000.

Common Target Sizes

These are the sizes the major platforms recommend for uploads. Platforms change their layouts from time to time, so check the platform's own help page if an upload looks cropped.

Look at the "Shape" column before you resize. If your photo has a different shape from the target, resizing alone cannot fix it. See the example below.

How the Aspect Ratio Math Works

The aspect ratio is width divided by height. When the lock is on, the tool keeps that ratio and works out the missing number for you:

new height = original height × (new width ÷ original width)

• A 4000 × 3000 camera photo, new width 1200: 3000 × 1200 ÷ 4000 = 900. Result: 1200 × 900.
• A 6000 × 4000 photo, new width 1920: 4000 × 1920 ÷ 6000 = 1280. Result: 1920 × 1280.
• A 3024 × 4032 phone photo taken upright, new width 1080: 4032 × 1080 ÷ 3024 = 1440. Result: 1080 × 1440.

When the answer is not a whole number, the tool rounds it. A 1920 × 1080 image at width 1000 gives 562.5, which becomes 563.

Now the shape problem. Say you want a 4000 × 3000 photo as an Instagram portrait post (1080 × 1350). With the lock on, width 1080 gives a height of 810, not 1350. The photo is 4:3, and the post is 4:5. If you untick the lock and type 1080 × 1350, people will look tall and thin. The right way is to crop the photo to 4:5 first (for example, 2400 × 3000), then resize that to 1080 × 1350.

What Resizing Can and Cannot Do

Making a picture bigger does not add detail

Resizing an 800 × 600 image to 1600 × 1200 gives you four times as many pixels. But the new pixels are guessed from the old ones. The picture gets bigger, not sharper. Edges look soft, and small text gets blurry. If you need a large image, start from the largest original you have.

Resizing is not the same as cropping

Resizing keeps the whole picture and changes how many pixels it has. Cropping cuts parts away to change the framing or shape. Crop first, then resize.

Resizing is not the same as compressing

Resizing lowers the pixel count. Going from 4000 × 3000 (12 million pixels) to 1200 × 900 (about 1.1 million) removes roughly 90% of the pixels, so the file usually gets much smaller too. Compressing keeps the same width and height and makes the file smaller by saving it with less detail. If a site has a file size limit (for example, "under 200 KB"), resize to the size you need first, then compress if it is still too big.

Printing: pixels, inches, and DPI

For print, the rule is pixels needed = inches × DPI. 300 DPI is the usual target for photos you hold in your hand.

• 6 × 4 inch print at 300 DPI: 6 × 300 = 1800 and 4 × 300 = 1200, so 1800 × 1200 px.
• A4 page (210 × 297 mm, or 8.27 × 11.69 inches) at 300 DPI: about 2480 × 3508 px.

This tool changes the pixel size only. It does not write a DPI value into the file. That is fine, because print shops go by the pixel count. A 1800 × 1200 image prints well at 6 × 4 inches, whatever DPI label the file has.

Mistakes to Avoid

• Unticking the lock and typing both numbers. Unless the shape matches exactly, faces and round objects come out stretched. Crop to the right shape instead.
• Resizing the same JPG again and again. JPG and WebP files are saved at 92% quality each time. One save is hard to notice, but many rounds add blocky marks. Always resize from the original file.
• Keeping photos as PNG. PNG is great for logos, screenshots, and images with a see-through background. For photos, PNG files are often several times bigger than JPG. Convert the photo to JPG if the file size matters.
• Going much bigger than you need. A 4000 px image on a blog that shows it at 800 px just makes the page slow. Pick the size from the table above.
• Enlarging a tiny image for print. A 640 × 480 image is only enough for about a 2.1 × 1.6 inch print at 300 DPI. Making it bigger here will not change that.