Resize an image on Windows

Three ways to resize in Octoolo

Image › Image size… changes the picture you are working on, as described above, so a crop, a caption or a logo you add next works on the new size. Each layer keeps its own pixels underneath, which means a picture made smaller can be made larger again later without losing sharpness.

The size in Export. When only the saved copy should be smaller, leave the picture alone and choose a width under Size as you export: the full size, or 3840, 2560, 2048, 1920, 1600, 1280, 1080, 800 or 512 pixels, whichever are narrower than the picture. Any other width goes in the W box beside the list. The height follows, so nothing is stretched, and the line under the settings shows the new width and height and about how big the file will be.

File › Many pictures at once…, Resize is a quick tool for a picture you only want resized, without opening it in the editor:

• Size by Pixels: a width and a height from 1 to 16000. With Keep proportions on, the other side follows.
• Size by Percent: any scale from 1% to 1000%. 50% halves both sides.
• Format: Same, PNG, JPG or WebP, with a quality slider for JPG and WebP.

It shows the original and the result side by side, each with its pixel size and file size, and saves the copy as “photo-resized.jpg”. Drop several pictures and the same settings apply to all of them: each row has its own Save, Save all as ZIP saves them together, and Open other pictures starts over.

Reduce image size: pixels or kilobytes?

“Reduce image size” can mean two things, and it helps to know which one you are after.

• Fewer pixels. A 12-megapixel phone photo is about 4000 pixels wide, far more than most screens show. Resized to 1920 or 1280, it looks the same on screen, sends faster and loads quicker.
• Fewer kilobytes. An upload form that says “under 1 MB” cares about the file, not the width. Lowering the JPG or WebP quality shrinks the file without changing its dimensions; the image compressor page explains how.

The best results usually come from both: resize first, then export at a quality between 80 and 90. Fewer pixels to store means a much smaller file before the quality setting even starts its work.

Which width to choose

These are widths. A portrait photo keeps its shape, so 1080 wide may be 1440 tall. When a site sets a limit on the longest side instead, type that number as the height in Image size with Keep the proportions ticked, or use Make smaller in File › Many pictures at once…, which has a Longest side box. If the shape itself must change, crop the image first.

Prints are the exception. A 6 × 4 inch print at 300 pixels per inch needs 1800 × 1200 pixels, and bigger prints need more, so print from the full size whenever you can.

Making a picture larger

Image size goes up as well as down: type a bigger width, or a percent above 100. Octoolo fills in the new pixels with smooth resampling, the way most editors do. That suits a small logo that must fill a slot, but it cannot invent detail: a soft picture gets bigger and stays soft.

For more than that, Image › Upscale 2× (AI) and Upscale 4× (AI) enlarge the picture with an AI model that runs on your PC and draws sharper edges and texture than resampling can. The image upscaler page explains what to expect. Either way, the largest picture the Photo Editor holds is set by your graphics card, 16,384 pixels a side on most PCs.

Paint, which comes with Windows, can also resize a single picture through Resize and skew (Ctrl W), by percent or by pixels. Octoolo adds the file size before you save, the choice of format and quality, AI enlarging, and a new file that leaves the original alone.