Claude Sonnet 4.5 vs Gemini 3.5 Flash
Benchmarks, API pricing and specs, head to head. Data updated 2026-06-10.
Claude Sonnet 4.5
65.5Anthropic · Sep 2025
The model that made 30-hour autonomous coding sessions real — 77.2% SWE-bench Verified and a 1M-token context beta at $3/$15.
Gemini 3.5 Flash
Google · May 2026
Google's I/O 2026 headliner: near-Pro intelligence at Flash speed, 78.8% on SWE-bench Verified with full multimodal input.
The verdict
Gemini 3.5 Flash wins 1 of the 1 benchmarks these models share, against 0 for Claude Sonnet 4.5. Gemini 3.5 Flash is about 1.8x cheaper per blended million tokens (3:1 input:output mix). Gemini 3.5 Flash also takes 1M of context versus 200K for Claude Sonnet 4.5.
Benchmark head-to-head 0–1
Specs & pricing
| Claude Sonnet 4.5 | Gemini 3.5 Flash | |
|---|---|---|
| modhub Index | 65.5 | — |
| Input price / 1M | $3 | $1.5 |
| Output price / 1M | $15 | $9 |
| Context window | 200K | 1M |
| Max output | 64K | 66K |
| Open weights | no | no |
| Reasoning model | yes | yes |
| Multimodal input | text, image | text, image, audio, video |
| Knowledge cutoff | Jan 2025 | Feb 2026 |
| Released | Sep 2025 | May 2026 |
| Example monthly cost* | $52.50 | $28.50 |
* 10M input + 1.5M output tokens per month at list prices, no caching. Green = better value on that row.
Frequently asked questions
- Which is better, Claude Sonnet 4.5 or Gemini 3.5 Flash?
- Gemini 3.5 Flash wins 1 of the 1 benchmarks these models share, against 0 for Claude Sonnet 4.5. Gemini 3.5 Flash is about 1.8x cheaper per blended million tokens (3:1 input:output mix). Gemini 3.5 Flash also takes 1M of context versus 200K for Claude Sonnet 4.5.
- Which is cheaper, Claude Sonnet 4.5 or Gemini 3.5 Flash?
- Claude Sonnet 4.5 costs $3/$15 per million input/output tokens, while Gemini 3.5 Flash costs $1.5/$9. For a typical workload of 10M input and 1.5M output tokens per month, that's $52.50 versus $28.50.
- Which model is better for coding, Claude Sonnet 4.5 or Gemini 3.5 Flash?
- On SWE-bench Verified — the standard agentic-coding benchmark — Gemini 3.5 Flash scores 78.8% versus 77.2% for Claude Sonnet 4.5, making Gemini 3.5 Flash the stronger pick for coding agents.
More comparisons
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