How do I calculate aspect ratio from pixels?+
Divide width by height and simplify using the greatest common divisor (GCD). For example, 1920x1080 - GCD is 120 - giving 16:9. This tool does the calculation instantly.
What are the standard aspect ratios?+
16:9 (HD video, YouTube), 4:3 (old TV, iPad), 1:1 (Instagram square), 9:16 (TikTok, Stories), 21:9 (ultrawide monitors), 3:2 (DSLR photos, 4x6 prints), 4:5 (Instagram portrait).
How do I resize keeping the same aspect ratio?+
Enter your original width and height, then enter either the new width or new height. The tool calculates the other dimension automatically to maintain the exact ratio.
What aspect ratio should I use for YouTube thumbnails?+
YouTube thumbnails should be 1280x720 pixels (16:9 ratio, minimum 640 pixels wide). This matches the widescreen format of the video player.