Physical Dimensions & Thickness: The Anbernic RG556 has a horizontal bar chassis measuring 223 × 105 × 15 mm, while the ASUS ROG Ally uses a horizontal bar chassis measuring 280 × 113 × 39 mm. In width, the Anbernic RG556 is 57 mm (20.4%) narrower than the ASUS ROG Ally. In height, the Anbernic RG556 is 8 mm (7.1%) shorter than the ASUS ROG Ally. In chassis thickness (depth), the Anbernic RG556 is 24 mm (61.5%) slimmer than the ASUS ROG Ally (15 mm vs 39 mm).
Footprint Area & Weight: Calculating surface footprint (width × height), the Anbernic RG556 occupies 23,415 mm² (234.2 cm²), compared to 31,640 mm² (316.4 cm²) for the ASUS ROG Ally—a footprint difference of 8,225 mm² (26%). On the scale, the Anbernic RG556 weighs 331g versus 608g for the ASUS ROG Ally, representing a 277g (45.6%) weight difference (Anbernic RG556 is lighter).
4:3 vs 16:9 Effective Viewable Screen Size: For classic 4:3 retro games (PS1, SNES, N64, Dreamcast), the Anbernic RG556's 5.48" (16:9) panel yields a 4.48" effective diagonal (75% active screen area with vertical pillarbox bars on the sides (native 16:9)), while 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)). This gives the ASUS ROG Ally a 1.24" larger active 4:3 diagonal (63.2% more active display area). For 16:9 widescreen content (PSP, Switch, streaming), the Anbernic RG556 delivers a 5.48" effective diagonal (100% screen usage) versus 7" (100% screen usage) on the ASUS ROG Ally, making the ASUS ROG Ally larger by 1.52" (+63.2% active 16:9 area).