Resize your image to 2560x1440 pixels, the best size for an HD YouTube thumbnail, using this free template. Upload your own image or thumbnail to this template and publish to get a 2560 by 1440 JPG file. You can also design your thumbnail image in the editor, changing the color of the background, adding title or teaser text, and inserting sticker overlays to attract viewers on YouTube. Position your image in the middle or crop off the extra when resizing to this ideal aspect ratio. For more instructions on creating 2560 x 1440 thumbnails for YouTube, check out this resource on designing thumbnails for YouTube .