# Resize Images — Resize images in pixels, percent, cm or inches on Mac Resize by longest edge, exact pixels, percentage, or print size in cm, mm or inches at the DPI you need. Part of OneMacTools, 151 private tools in one native Mac app (macOS 26 or later); category: Images. Runs on your Mac; nothing is uploaded. Resize a batch of images by the longest edge, to an exact width and height, or by a percentage. For printing, choose a size like 4 × 6 in, 5 × 7 in, A4 or passport, or type your own in cm, mm or inches, pick the DPI (72, 150, 300 or 600), and OneMacTools works out the pixels and saves the DPI in the file. Fit within, crop to fill around the subject, or stretch. Page: https://www.onemactools.com/tools/resize-images · Download: https://www.onemactools.com/download · Pricing: https://www.onemactools.com/pricing ## How to use it 1. **Drop your images.** Add one image or a whole folder's worth. They're all resized with the same settings. 2. **Choose how to resize.** Pick Longest edge, Exact size (px), Percentage or Print size (cm / mm / in). The options below change to match. 3. **Set the size and fit.** Choose the pixels, percentage or print size. For exact and print sizes, pick whether to fit within, crop to fill or stretch. 4. **Click Resize.** Each copy gets the new size in its name, such as “1600px”, “50%” or “300dpi”. 5. **Use the copies.** The resized images are saved in a new dated folder in Downloads › OneMacTools. Open them with the Preview (eye) button or Show in Finder. Your originals are left alone. ## Options - **Resize by:** Longest edge scales every image so its longer side is a set length, whatever its shape. Exact size (px) makes every image the same width and height. Percentage scales up or down by a fixed amount. Print size works out the pixels from a size in cm, mm or inches and a DPI. - **Longest edge:** Shown for Longest edge: 3840, 2048, 1600 (the default), 1280, 1080, 1024, 640 or 320 px. Images already smaller than this are left at their size. - **Width × height (px):** Shown for Exact size: type the size, such as 1200 x 800. - **Scale to:** Shown for Percentage: 10%, 25%, 50% (the default), 75%, 150% or 200%. - **Print size:** Shown for Print size: 4 × 6 in (10 × 15 cm), 5 × 7 in (13 × 18 cm), A4, A5, Passport (3.5 × 4.5 cm), 2 × 2 in, or Custom. The print turns to match each photo, so a landscape photo makes a landscape print. - **Width × height:** Shown for a Custom print size: type it with decimals if you need them, such as 9 x 13 or 8.5 x 11. - **Unit:** Shown for a Custom print size: cm, mm or in. - **DPI:** Shown for Print size: 72, 150, 300 (the default) or 600. 300 DPI is the standard for photo prints. The DPI is saved in the file so printing apps use the right size. - **Fit:** Shown for Exact size and Print size. Fit within keeps the whole picture, so one side may come out smaller than the target. Crop to fill hits the exact size by trimming the edges, keeping faces and the main subject in view. Stretch to fill hits the exact size by distorting the picture. - **Save as:** Same as original, JPEG, PNG or HEIC. Same as original keeps PNG, JPEG, HEIC, AVIF and TIFF as they are and saves other formats as PNG. ## Tips - For websites and email, Longest edge is usually the right choice: portrait and landscape photos both come out the right size without cropping. - Use Crop to fill when every image must be exactly the same shape, such as product photos for a shop grid. - Avoid Stretch to fill for photos of people or products. It changes their proportions; Crop to fill is almost always better. - Making a photo bigger can't add detail. For prints, check the photo has enough pixels: a 10 × 15 cm print at 300 DPI needs about 1181 × 1772 px. - Resize before you compress. A smaller image in pixels is much smaller on disk, and Compress Images can then finish the job. ## Questions **How do I resize a photo for printing at 10 × 15 cm?** Choose Print size, pick 4 × 6 in (10 × 15 cm) or type your own size in cm, mm or inches, and choose 300 DPI. OneMacTools works out the pixels (1181 × 1772 at 300 DPI) and saves the DPI in the file. **Will resizing make my photo blurry?** Making a photo smaller keeps it sharp. Making it bigger can't add detail that isn't there, so enlarged photos look softer. **What's the difference between Fit within and Crop to fill?** Fit within keeps the whole photo, so one side may come out smaller than the target. Crop to fill hits the exact size by trimming the edges, keeping faces and the subject in view. **How do I resize many images to the same width on a Mac?** Choose Longest edge and pick a size if your images all have the same orientation. If they mix portrait and landscape and must match exactly, use Exact size (px) with Crop to fill. **How do I make a photo smaller in pixels without cropping it?** Use Longest edge or Percentage. Both keep the whole picture and its proportions. **What DPI should I choose?** 300 DPI for photo prints and anything you'll look at up close, 150 DPI for posters viewed from a distance, and 600 DPI for fine line art. DPI only matters for printing; on screen, the pixel size is what counts. **Can I resize to an exact size like 1200 × 800?** Yes. Choose Exact size (px), type 1200 x 800 and pick how to fit: crop to fill for exactly that size, or fit within to keep the whole picture.