To resize several images at once click on the Resize item of the Batch Converting Dialog. At the right pane of the Batch Converting Dialog the Resizing Options will appear. Uncheck the Actual size checkbox and set width and height for all new images. Or uncheck the Actual size checkbox, check on the Proportional in percentages from a source checkbox and set a scale in percentages for all converted images. Images will be increased (if the Scale value is larger than 100%) or decreased (if the Scale value is smaller than 100%). Refer also to the Resizing Options window topic.