If you demand to reduce the size of an paradigm (or images) considering they are too large to email, to utilise online, or for some other reason, you may exist thinking that you need an expensive app such as Photoshop, simply you tin can hands resize images on a Mac using Preview, which comes free with macOS.

Hither'due south how to resize images on Mac, including how to resize images without losing quality, resize images without stretching or distorting, how to resize images to aforementioned height and width and more.

Offset we'll look at the basics...

How to resize an image using Preview

Here'southward what you need to do to change the dimensions of an image using Preview.

  1. Locate the paradigm (either using the Finder, or on your Desktop).
  2. Double click on the image - this should open the paradigm in Preview, if it doesn't, close it and right click to cull Open With and select Preview.
  3. Click on Tools.
  4. Choose Conform Size (you lot tin also open this card by clicking on the square with arrows icon in the bill of fare bar). Adjust Size Preview
  5. At present, assuming desire your image to look the same after - rather than stretched or squat, you lot demand to make certain that Scale proportionally is selected. This means you lot tin can only change one dimension, length or width, but it means everything will be adjusted as. Change dimensions image Mac
  6. Choose whether you want to resize according to pixels, percent, inches, cm, mm or points.
  7. Conform either the Width number or the Height number - the other volition automatically adjust proportionally.

That will change the dimensions of the image, perhaps yous need the width to exist the same every bit the width of a webpage you are adding the prototype to, for instance. But what if it's the size of the epitome - in terms of MB - yous want to change?

How to make an image smaller

If you are trying to make the size of the prototype smaller (perhaps so you can send it via email) in that location are a couple of ways you can practise so.

If you open the Accommodate Size menu as in a higher place you lot volition observe that when you conform the dimensions of the prototype you will run into a preview of the size (in MB or KB) of the prototype before and later on yous accept make your changes. (It may take a while to calculate the size.)

If you are trying to shrink the paradigm to 500KB for example, you can go on adjusting until you are happy with the result here.

Another way to suit the size of the prototype is via the quality settings in the Export menu.

  1. Click on File > Export.
  2. You lot will run into various file formats to choose from. HEIC (the new file format), JPEG, JPEG-2000, OpenEXR, PDR, PNG or TIFF. Below the list is a measurement of file size. If you click through the different file options you tin can come across the file size change. JPEG is smaller than PNG, TIFF is bigger than PNG, for example. Yous could merely select JPEG to get a smaller file size. Format choices
  3. Even having selected JPEG you tin become a stride farther to reduce the file size by sliding the Quality bar from Best to Least. But adjust it until you get to a size that suits y'all. But remember that some of the quality volition be lost.
  4. When you lot are happy click on Save.Size of Jpeg

How to adapt an paradigm, but maintain 300dpi

Speaking of quality… Y'all may also desire to get the best issue possible at 300dpi (unremarkably recommended for print), or another resolution. In that case, hither's what to do:

  1. Deselect Resample image (scale proportionally will remain selected but greyed out.)
  2. In the department where it says resolution pixels/inch change the number to 300 (or whatever dpi is requested). 300dpi image Preview
  3. You will discover that the width and top measurements will adjust, click OK.
  4. This won't accommodate the actual size of the file, only it means that if the image was printed it would be smaller, but clearer, thanks to more meaty pixels.

Resizing to particular dimensions

What if you want to resize both the pinnacle and width of your paradigm to detail dimensions, such as 1,600 x 900?

In Preview the best way to practise this is to utilize the ingather tool. We'll look at how to do that adjacent.

How to crop an image in Preview

If you desire to ingather an prototype it's non immediately obvious how to do so because there isn't a traditional crop tool in the carte du jour, but it's actually very easy.

  1. Click on the paradigm in Preview and drag so that the blue box surrounds the office of the image y'all desire to crop.
  2. If you desire the image to be a particular size, like i,600 x 900 in the case higher up, you can drag the box to the dimensions you need. You will see a little counter in the bottom right corner that shows how many pixels are selected. Crop in Preview
  3. Once you have the correct sized box un-click the mouse, and you'll exist able to motion the box to prime number position.
  4. Once y'all are happy click command + K and that volition crop the image.

Resize without losing quality

You can't add pixels to an image so the only mode to brand an paradigm larger without losing quality (which is determined by the number of pixels in a square inch) is to crop the image post-obit the instructions above.

Even so you could choose HEIC, which is a infinite saving file type (it stands for Loftier Efficiency Image Format) that should create an image that is smaller than a JPEG, but with the aforementioned quality.

HEIC files are one-half the size of a JPEG but offer the aforementioned quality.

HEIC in Preview

You tin only open a HEIC file on a Mac with High Sierra or Mojave installed, or on iPhones and iPads running iOS 11 or iOS 12.

We accept an article about opening HEIC files on our sister site Tech Advisor. The advice is to use a third political party app, such equally such as iMazing HEIC Converter or Apowersoft's HEIC to JPG converter, or an online converter such as HEIC to JPG.

How to batch resize

You tin can also batch resize if in that location are a number of images you want to arrange in i get. To do and then:

  1. Select all the images you want to resize by clicking on each one in the Finder, or on your Desktop, while pressing the Command fundamental.
  2. Right click and cull Open with Preview.
  3. All the images volition open in Preview. Select all by pressing Command + A (or choose Edit > Select All).
  4. Now get to Tools > Arrange Size (equally we did earlier).
  5. If you are simply adjusting width or height don't forget to select Scale Proportionally.
  6. You will run across Multiple Values announced equally the measurement in the columns (bold all the images are dissimilar sizes). If you want them all to be thou pixels wide, type one thousand in the Width box. Batch resize Mac
  7. Click OK to adjust the size of the selected images.
  8. Now press Control + South to salvage (or File > Relieve) and all your images volition be saved with the new dimensions.

How to alter the file format

Speaking of saving what if y'all want to change the file format of the image. We touched on this before when we discussed reducing the file size as some file formats are smaller than others.

  1. To change the file format click on File in the bill of fare.
  2. Click Export…
  3. From the Format dropdown many cull either HEIC (the new file format), JPEG, JPEG-2000, OpenEXR, PDR, PNG or TIFF.
  4. With some of these options you tin also adjust quality (and therefore size). e.g. if yous select JPEG you will meet a quality slider and it will show you lot the file size so you lot can adjust information technology downwardly to a size that suits yous.Format for image
  5. When you are happy click on Save.

Nosotros have more tips for using Preview on the Mac hither. We as well have data about how yous can use Preview to sign a PDF on a Mac and how to edit PDFs on a Mac.