1. At the bottom of the window, click the cogwheel next to Output format:
To batch resize, please add all the files you want to resize. Resizing will be applied to all the added files.
2. Click the box under Frame size and choose a size that you want to use for all images, or choose any of the following and enter the size into the width and height boxes on the right:
Custom: scales the images to exactly the size you specify.
Smart fit: scales the images up or down as close as possible to the specified sizewithout changing the proportions.
Up to size: scales the images down as close as possible to the specified size without changing the proportions. Images smaller than this size will remain unchanged.To allow changing the image proportions, click the link icon next to the width and height boxes: 
– locked, 
– unlocked.
3. If the new size is different from the original image proportions, choose a resize method for your images:
Letter box – unused space will be filled with black.
Stretch – the image will stretch to fill the entire area.
Crop – the image will be resized to fill the entire area, and overflowing edges will be cut off.
4. Click OK to accept the changes. If you want to preview the result, click the Edit button next to an image.
5: Convert
The resulted file will be produced with the specified resolution.