How to resize picture in MacOS

If you used blogger or google page, or wordpress... you will see sometimes you need to change your image size because most of the websites only accept very small image.
This is a step-by-step instruction with illustration for you.
Step 1: Open Finder and navigate to your image folder
Step 2: Open your image with Preview application by right click and choose open with Preview

Step 3: Inside Preview, choose Tools\Adjust size...

Step 4: Type in your width and height, click the lock to unlock the ratio if you want to change the ratio of your picture. Then click OK

Step 5: Click File\ Save a version to save your file. Remember if you want to keep the original file (as usual), please choose Duplicate in the next warning of Preview

The warning from system that you might duplicate the file to keep the original.
Now you have your picture ready with desired size.
If you have any questions, please leave comment below, I'll try to help.