Claude Sonnet 4.5 vs Gemini 2.5 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 2.5 Flash
Google · Jun 2025
The 2025 fast-tier favorite: hybrid reasoning, full multimodality and a 1M context at $0.30/$2.50.
The verdict
Claude Sonnet 4.5 wins 3 of the 3 benchmarks these models share, against 0 for Gemini 2.5 Flash. On price the gap is dramatic: Gemini 2.5 Flash works out roughly 7.1x cheaper per blended million tokens. Gemini 2.5 Flash also takes 1.0M of context versus 200K for Claude Sonnet 4.5.
Benchmark head-to-head 3–0
Specs & pricing
| Claude Sonnet 4.5 | Gemini 2.5 Flash | |
|---|---|---|
| modhub Index | 65.5 | — |
| Input price / 1M | $3 | $0.3 |
| Output price / 1M | $15 | $2.5 |
| Context window | 200K | 1.0M |
| Max output | 64K | 66K |
| Open weights | no | no |
| Reasoning model | yes | yes |
| Multimodal input | text, image | text, image, audio, video |
| Knowledge cutoff | Jan 2025 | Jan 2025 |
| Released | Sep 2025 | Jun 2025 |
| Example monthly cost* | $52.50 | $6.75 |
* 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 2.5 Flash?
- Claude Sonnet 4.5 wins 3 of the 3 benchmarks these models share, against 0 for Gemini 2.5 Flash. On price the gap is dramatic: Gemini 2.5 Flash works out roughly 7.1x cheaper per blended million tokens. Gemini 2.5 Flash also takes 1.0M of context versus 200K for Claude Sonnet 4.5.
- Which is cheaper, Claude Sonnet 4.5 or Gemini 2.5 Flash?
- Claude Sonnet 4.5 costs $3/$15 per million input/output tokens, while Gemini 2.5 Flash costs $0.3/$2.5. For a typical workload of 10M input and 1.5M output tokens per month, that's $52.50 versus $6.75.
- Which model is better for coding, Claude Sonnet 4.5 or Gemini 2.5 Flash?
- On SWE-bench Verified — the standard agentic-coding benchmark — Claude Sonnet 4.5 scores 77.2% versus ~48.9% for Gemini 2.5 Flash, making Claude Sonnet 4.5 the stronger pick for coding agents.
More comparisons
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