Head-to-head
Claude Sonnet 4.6 vs Gemini 3.5 Flash
Compare Claude Sonnet 4.6 and Gemini 3.5 Flash on the metrics that decide an agent workload.
| Metric | Claude Sonnet 4.6 | Gemini 3.5 Flash |
|---|---|---|
| Provider | Anthropic | Google Gemini |
| Input / 1M | $3.00 | $1.50 |
| Output / 1M | $15.00 | $9.00 |
| Cache read / 1M | $0.30 (−90%) | $0.15 (−90%) |
| Reuse-adj @55% | $4.89 | $2.82 |
| Context | 1M | 1M |
| Cache capture | 94% | 85% |
| Warm TTFT | 190ms (−65%) | 150ms (−61%) |
| Quality index | 88 | 94 |
Teal marks the better value in each row. Reuse-adjusted assumes 55% prefix reuse and a 25% output share.
Pick Claude Sonnet 4.6 when it captures more of the available reuse.
Pick Gemini 3.5 Flash when it scores higher on the composite quality index, it is cheaper once prefix reuse is priced in, it carries the larger 1M context window.
Gemini 3.5 Flash wins on both reuse-adjusted cost and quality here, so it is the default pick. Reach for Claude Sonnet 4.6 only when a specific constraint (modality, latency floor, or licensing) forces it.
Frequently asked
Claude Sonnet 4.6 vs Gemini 3.5 Flash, answered.
Is Claude Sonnet 4.6 or Gemini 3.5 Flash cheaper?
At 55% prefix reuse, Claude Sonnet 4.6 blends to about $4.89 per 1M tokens and Gemini 3.5 Flash to about $2.82. Gemini 3.5 Flash 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?
Claude Sonnet 4.6 shows higher measured cache capture (94% vs 85%) 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.