If you are trying to shrink the image to 500KB for example, you can keep adjusting until you are happy with the result here. (It may take a while to calculate the size.) If you open the Adjust Size menu as above you will notice that when you adjust the dimensions of the image you will see a preview of the size (in MB or KB) of the image before and after you have make your changes. If you are trying to make the size of the image smaller (perhaps so you can send it via email) there are a couple of ways you can do so. But what if it’s the size of the image – in terms of MB – you want to change? How to make an image smaller That will change the dimensions of the image, perhaps you need the width to be the same as the width of a webpage you are adding the image to, for example. Adjust either the Width number or the Height number – the other will automatically adjust proportionally.Choose whether you want to resize according to pixels, percent, inches, cm, mm or points.This means you can only change one dimension, length or width, but it means everything will be adjusted equally. Now, assuming want your image to look the same after – rather than stretched or squat, you need to make sure that Scale proportionally is selected.Choose Adjust Size (you can also open this menu by clicking on the square with arrows icon in the menu bar).Double click on the image – this should open the image in Preview, if it doesn’t, close it and right click to choose Open With and select Preview.Locate the image (either using the Finder, or on your Desktop).The aspect ratio is the proportional relationship between the two sides of the image (width and height). Next, decide whether you want to keep the aspect ratio of the original image. Many people use “Percent” for eyeballing relative size changes, but if you’re resizing images for the web, you’ll probably want to choose “Pixels” from the list. Columns: This lets you resize by the number of columns, an arbitrary unit defined in Preferences > Units & Rulers.Picas: One pica is equal to 1/6th of an inch or 12 points, and it’s used most frequently in design for print.In a 72-DPI resolution image, one point is equal to one pixel. Points: A point is a unit of measurement common in typography that is equivalent to 1/72nd of an inch.Inches, Centimeters, Millimeters: These are standard measurement sizes that only apply when an image is printed, and they are related to the image’s DPI.Pixels: This lets you specify exact pixel dimensions for the resulting image size.For example, using 50% as the target image size makes the image half of its current size. Percent: This lets you resize by a percent of the current image size.

If you click the drop-down menu beside the “Width” or “Height” fields, you can choose the unit type. In the “Image Size” window, first, you’ll want to decide what measurement unit you’ll use to resize the image.

How to change a picture size on mac