OpenAI gpt-oss-120b vs Grok 4.3
Compare OpenAI gpt-oss-120b and Grok 4.3 on the metrics that decide an agent workload.
| Metric | OpenAI gpt-oss-120b | Grok 4.3 |
|---|---|---|
| Provider | Fireworks AI | xAI |
| Input / 1M | $0.15 | $1.25 |
| Output / 1M | $0.60 | $2.50 |
| Cache read / 1M | $0.01 (−90%) | $0.20 (−84%) |
| Reuse-adj @55% | $0.21 | $1.13 |
| Context | 131K | 1M |
| Cache capture | 79% | 76% |
| Warm TTFT | 120ms (−64%) | 280ms (−56%) |
| Quality index | 79 | 92 |
Teal marks the better value in each row. Reuse-adjusted assumes 55% prefix reuse and a 25% output share.
Pick OpenAI gpt-oss-120b when it is cheaper once prefix reuse is priced in, it answers faster on warm cache hits, it captures more of the available reuse.
Pick Grok 4.3 when it scores higher on the composite quality index, it carries the larger 1M context window.
Grok 4.3 leads on quality while OpenAI gpt-oss-120b leads on reuse-adjusted cost. Send latency- and budget-sensitive volume to OpenAI gpt-oss-120b and reserve Grok 4.3 for the hard requests. Zumik's aliases route between them automatically under policy.
OpenAI gpt-oss-120b vs Grok 4.3, answered.
Is OpenAI gpt-oss-120b or Grok 4.3 cheaper?
At 55% prefix reuse, OpenAI gpt-oss-120b blends to about $0.21 per 1M tokens and Grok 4.3 to about $1.13. OpenAI gpt-oss-120b is cheaper on that basis.
Which has the larger context window?
Grok 4.3 has the larger window: 1M vs 131K tokens.
Which captures more reuse?
OpenAI gpt-oss-120b shows higher measured cache capture (79% 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.