Gemini 3.5 Flash vs Grok 4.3
Compare Gemini 3.5 Flash and Grok 4.3 on the metrics that decide an agent workload.
| Metric | Gemini 3.5 Flash | Grok 4.3 |
|---|---|---|
| Provider | Google Gemini | xAI |
| Input / 1M | $1.50 | $1.25 |
| Output / 1M | $9.00 | $2.50 |
| Cache read / 1M | $0.15 (−90%) | $0.20 (−84%) |
| Reuse-adj @55% | $2.82 | $1.13 |
| Context | 1M | 1M |
| Cache capture | 81% | 76% |
| Warm TTFT | 150ms (−61%) | 280ms (−56%) |
| Quality index | 86 | 92 |
Teal marks the better value in each row. Reuse-adjusted assumes 55% prefix reuse and a 25% output share.
Pick Gemini 3.5 Flash when it carries the larger 1M context window, 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 is cheaper once prefix reuse is priced in.
Grok 4.3 wins on both reuse-adjusted cost and quality here, so it is the default pick. Reach for Gemini 3.5 Flash only when a specific constraint (modality, latency floor, or licensing) forces it.
Gemini 3.5 Flash vs Grok 4.3, answered.
Is Gemini 3.5 Flash or Grok 4.3 cheaper?
At 55% prefix reuse, Gemini 3.5 Flash blends to about $2.82 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?
Gemini 3.5 Flash has the larger window: 1M vs 1M tokens.
Which captures more reuse?
Gemini 3.5 Flash shows higher measured cache capture (81% 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.