Physical Dimensions & Thickness: The ASUS ROG Ally has a horizontal bar chassis measuring 280 × 113 × 39 mm, while the Powkiddy X55 uses a horizontal bar chassis measuring 212.5 × 94.5 × 19 mm. In width, the ASUS ROG Ally is 67.5 mm (31.8%) wider than the Powkiddy X55. In height, the ASUS ROG Ally is 18.5 mm (19.6%) taller than the Powkiddy X55. In chassis thickness (depth), the ASUS ROG Ally is 20 mm (105.3%) thicker than the Powkiddy X55 (39 mm vs 19 mm).
Footprint Area & Weight: Calculating surface footprint (width × height), the ASUS ROG Ally occupies 31,640 mm² (316.4 cm²), compared to 20,081 mm² (200.8 cm²) for the Powkiddy X55—a footprint difference of 11,559 mm² (57.6%). On the scale, the ASUS ROG Ally weighs 608g versus 293g for the Powkiddy X55, representing a 315g (107.5%) weight difference (Powkiddy X55 is lighter).
4:3 vs 16:9 Effective Viewable Screen Size: For classic 4:3 retro games (PS1, SNES, N64, Dreamcast), the ASUS ROG Ally's 7" (16:9) panel yields a 5.72" effective diagonal (75% active screen area with vertical pillarbox bars on the sides (native 16:9)), while the Powkiddy X55's 5.5" (16:9) panel yields a 4.49" effective diagonal (75% active screen area with vertical pillarbox bars on the sides (native 16:9)). This gives the ASUS ROG Ally a 1.23" larger active 4:3 diagonal (62% more active display area). For 16:9 widescreen content (PSP, Switch, streaming), the ASUS ROG Ally delivers a 7" effective diagonal (100% screen usage) versus 5.5" (100% screen usage) on the Powkiddy X55, making the ASUS ROG Ally larger by 1.5" (+62% active 16:9 area).