GPT-5.5 vs Grok 4.3
Frontier general models with different cost-control levers.
| Metric | GPT-5.5 | Grok 4.3 |
|---|---|---|
| Provider | OpenAI | xAI |
| Input / 1M | $5.00 | $1.25 |
| Output / 1M | $30.00 | $2.50 |
| Cache read / 1M | $0.50 (−90%) | $0.20 (−84%) |
| Reuse-adj @55% | $9.39 | $1.13 |
| Context | 1.1M | 1M |
| Cache capture | 88% | 76% |
| Warm TTFT | 240ms (−67%) | 280ms (−56%) |
| Quality index | 96 | 92 |
Teal marks the better value in each row. Reuse-adjusted assumes 55% prefix reuse and a 25% output share.
You want automatic caching plus a 50% batch tier for background work.
You want real-time knowledge behavior and accept that cost control rests on caching and routing, not batch.
GPT-5.5 has more cost levers thanks to its batch tier; Grok 4.3 competes on freshness and latency. Route background traffic away from xAI.
GPT-5.5 vs Grok 4.3, answered.
Is GPT-5.5 or Grok 4.3 cheaper?
At 55% prefix reuse, GPT-5.5 blends to about $9.39 per 1M tokens and Grok 4.3 to about $1.13. Grok 4.3 is cheaper on that basis.
Which has the larger context window?
GPT-5.5 has the larger window: 1.1M vs 1M tokens.
Which captures more reuse?
GPT-5.5 shows higher measured cache capture (88% vs 76%) in the Zumik corpus.
Let an alias pick for you.
Route to whichever model wins under current policy automatically. Zumik resolves the alias to the best fit per request, so you never hard-code a loser.