GPT-5.5 vs Grok 4.20
The comparison
On LM Arena, GPT-5.5 scores higher (1481 Elo vs 1474 Elo), from a smaller review base (28,268 vs 42,370 Arena votes).
As of Jun 24, 2026, GPT-5.5 is rated 1481 Elo on LM Arena (28,268 Arena votes); Grok 4.20 is rated 1474 Elo on LM Arena (42,370 Arena votes). No source is blended; each stands on its own.