Model comparison
Claude Sonnet 4.5 vs Composer 2 Fast
Head-to-head evidence from 0 shared benchmark results across 0 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.
Public leaderboard positions: Claude Sonnet 4.5 #98 (Estimated); Composer 2 Fast unranked (Not scored). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.
Evidence parity. Claude Sonnet 4.5 and Composer 2 Fast share 0 comparable benchmark results. 0 of 8 categories are comparable. 12 results are unique to Claude Sonnet 4.5; 1 to Composer 2 Fast.
Updated July 28, 2026- Shared results
- 0
- Claude Sonnet 4.5 only
- 12
- Composer 2 Fast only
- 1
- Comparable categories
- 0 / 8
Benchmark data for Claude Sonnet 4.5 and Composer 2 Fast is coming soon on BenchLM.
Confidence note. This is a partial-evidence comparison with 0 shared benchmark results across 0 evidence categories; 0 of 8 categories currently have scoreable aggregates for both models. Treat the verdict as directional until coverage is more balanced.
Why this result
BenchLM has partial data for these models, but not enough overlapping benchmark coverage to produce a fair score-level comparison yet.
Operational comparison
Runtime and commercial metrics are compared only when both models have a complete sourced value.
| Metric | Claude Sonnet 4.5 | Composer 2 Fast | Comparison |
|---|---|---|---|
| Input / output priceUSD per 1M tokens | Claude Sonnet 4.5$3 input / $15 output | Composer 2 FastNot available | A complete price comparison is not available. |
| Generation speedtokens per second | Claude Sonnet 4.5Not available | Composer 2 FastNot available | A complete speed comparison is not available. |
| First-answer latencyseconds to first token | Claude Sonnet 4.5Not available | Composer 2 FastNot available | A complete latency comparison is not available. |
| Context windowmaximum listed tokens | Claude Sonnet 4.5200K | Composer 2 Fast200K | Listed context windows are equal. |
Benchmark Deep Dive
Agentic5 benchmarks
Coding2 benchmarks
Reasoning1 benchmarks
| Benchmark | Claude Sonnet 4.5 | Composer 2 Fast | Result |
|---|---|---|---|
| ARC-AGI-2Source | 13.6% | — | Not comparable |
Knowledge1 benchmarks
| Benchmark | Claude Sonnet 4.5 | Composer 2 Fast | Result |
|---|---|---|---|
| GPQASource | 83.4% | — | Not comparable |
Math3 benchmarks
Multimodal1 benchmarks
| Benchmark | Claude Sonnet 4.5 | Composer 2 Fast | Result |
|---|---|---|---|
| Design Arena WebsiteSource | 1215 | — | Not comparable |
Frequently Asked Questions (3)
Can I compare Claude Sonnet 4.5 and Composer 2 Fast on BenchLM yet?
Not fully yet. BenchLM is tracking both models, but the sourced benchmark breakdown for this comparison is still coming soon.
Why does this comparison show “coming soon”?
BenchLM only shows category winners and benchmark-level calls when we have sourced results that can be compared fairly. For these models, the public benchmark coverage is not complete enough yet.
What data is available for Claude Sonnet 4.5 and Composer 2 Fast today?
Claude Sonnet 4.5: $3.00 input / $15.00 output per 1M tokens Both model pages still include creator, context window, reasoning mode, and other metadata while benchmark coverage fills in.
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The model to choose, the cheaper alternative, and the release we would wait on.
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