The 40-inch ultrawide is 36.77" (93.4 cm) wide and 15.76" (40 cm) tall, while the 45-inch ultrawide is 41.36" (105.1 cm) wide and 17.73" (45 cm) tall. That makes the 45-inch ultrawide the larger screen by 26.6% of usable area.
The 40-inch ultrawide measures 36.77" (93.4 cm) wide by 15.76" (40 cm) tall, with a total screen area of 579.3 square inches. The 45-inch ultrawide measures 41.36" (105.1 cm) wide by 17.73" (45 cm) tall, covering 733.2 square inches.
The practical difference: the 45-inch ultrawide is 12.5% wider, the 45-inch ultrawide is 12.5% taller, and 45-inch ultrawide offers 26.6% more screen area. Width affects how much desk space you need, while the height delta shows how much vertical space changes for documents, timelines, and video.
The practical choice depends on what feels limiting in your current setup. For coding, timelines, spreadsheets, and games, the wider option gives more room for side-by-side windows, while the taller option keeps more vertical content visible without pushing the edges of the screen as far away. If your desk is shallow, width and viewing distance matter as much as raw diagonal size.
40-inch 21:9 vs 45-inch 21:9 is mostly about side-by-side workspace. A 21:9 display behaves like one wide main workspace, while a 32:9 super ultrawide is closer to two monitors fused into one panel. The physical width number matters more than the diagonal when you are checking speakers, arms, laptop stands, or portrait side screens.
At 5120x2160, the 40-inch ultrawide achieves 139 PPI. The 45-inch ultrawide at 5120x2160 reaches 123 PPI. The 40-inch ultrawide has 11.1% higher pixel density, resulting in sharper text and images.
For text-heavy work, PPI is the number that decides whether you are buying more room or just making everything bigger. A lower-PPI large screen can feel spacious for windows but softer for code and documents. A higher-PPI screen may need OS scaling, but it usually gives cleaner text and more flexible sizing.
For 16:9 content (most videos and games), the 40-inch ultrawide provides an effective diagonal of 32.1", while the 45-inch ultrawide provides 36.2". Check this if you watch 16:9 video or play games that do not support ultrawide resolutions.
Frequently Asked Questions
- What are the exact dimensions of a 40-inch ultrawide?
- A 40-inch ultrawide measures 36.77" (93.4 cm) wide by 15.76" (40 cm) tall, with a screen area of 579.3 square inches.
- What are the exact dimensions of a 45-inch ultrawide?
- A 45-inch ultrawide measures 41.36" (105.1 cm) wide by 17.73" (45 cm) tall, with a screen area of 733.2 square inches.
- Which is bigger: 40-inch ultrawide or 45-inch ultrawide?
- The 45-inch ultrawide is 26.6% larger in total screen area, though the 40-inch ultrawide may be taller depending on aspect ratio.
- How much desk space do I need for a 45-inch ultrawide?
- A 45-inch ultrawide requires at least 41.36" of desk width. We recommend 47.36" to allow comfortable margins on each side.
- How wide is 40-inch ultrawide compared with 45-inch ultrawide?
- The 40-inch ultrawide is 36.77" wide. The 45-inch ultrawide is 41.36" wide, so the width change is 4.6" before bezels, arms, or speaker space.
- Which has better pixel density: 40-inch ultrawide or 45-inch ultrawide?
- The 40-inch ultrawide at 5120x2160 has 139 PPI, which is 11.1% higher than the 45-inch ultrawide's 123 PPI.
- How does 16:9 content look on these displays?
- On the 40-inch ultrawide, 16:9 content appears at an effective 32.1" diagonal. On the 45-inch ultrawide, it appears at 36.2". Ultrawides display 16:9 content with black bars on the sides.