Model comparison
Claude Sonnet 4.5 vs GPT-5.5 Pro
Head-to-head evidence from 2 shared benchmark results across 1 category. Overall scores shown here use the public BenchAlign v5 ranking lane.
Public leaderboard positions: Claude Sonnet 4.5 #96 (Estimated); GPT-5.5 Pro #38 (Estimated). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.
Evidence parity. Claude Sonnet 4.5 and GPT-5.5 Pro share 2 comparable benchmark results. 3 of 8 categories are comparable. 10 results are unique to Claude Sonnet 4.5; 5 to GPT-5.5 Pro.
Updated July 22, 2026- Shared results
- 2
- Claude Sonnet 4.5 only
- 10
- GPT-5.5 Pro only
- 5
- Comparable categories
- 3 / 8
Pick GPT-5.5 Pro if you want the stronger benchmark profile. Claude Sonnet 4.5 only becomes the better choice if knowledge is the priority or you want the cheaper token bill.
Confidence note. This is a partial-evidence comparison with 2 shared benchmark results across 1 evidence category; 3 of 8 categories currently have scoreable aggregates for both models. Treat the verdict as directional until coverage is more balanced.
Why this result
GPT-5.5 Pro is clearly ahead on the BenchAlign aggregate, 63.69 to 53.61. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.
GPT-5.5 Pro's sharpest advantage is in mathematics, where it averages 48.1 against 11.2. The single biggest benchmark swing on the page is FrontierMath v2 (Tiers 1-3), 13.495% to 51.000%. Claude Sonnet 4.5 does hit back in knowledge, so the answer changes if that is the part of the workload you care about most.
GPT-5.5 Pro is also the more expensive model on tokens at $30.00 input / $180.00 output per 1M tokens, versus $3.00 input / $15.00 output per 1M tokens for Claude Sonnet 4.5. That is roughly 12.0x on output cost alone. GPT-5.5 Pro is the reasoning model in the pair, while Claude Sonnet 4.5 is not. That usually helps on harder chain-of-thought-heavy tests, but it can also mean more latency and more token spend in real use. GPT-5.5 Pro gives you the larger context window at 1M, compared with 200K for Claude Sonnet 4.5.
Category breakdown
Exact category averages are shown below. Not measured means BenchLM does not have enough sourced public coverage for that model and category.
| Category | Claude Sonnet 4.5 | Δ | GPT-5.5 Pro |
|---|---|---|---|
| Math | Claude Sonnet 4.511.2 | Margin→ 36.9 | GPT-5.5 Pro48.1 |
| Agentic | Claude Sonnet 4.555.4 | Margin→ 34.7 | GPT-5.5 Pro90.1 |
| Knowledge | Claude Sonnet 4.583.4 | Margin← 26.2 | GPT-5.5 Pro57.2 |
| Coding | Claude Sonnet 4.577.2 | MarginNo overlap | GPT-5.5 ProNot measured |
| Reasoning | Claude Sonnet 4.513.6 | MarginNo overlap | GPT-5.5 ProNot measured |
Decisive benchmark drivers
The largest measured benchmark gaps in this matchup, with exact reported values.
More
- Source ↗
FrontierMath v2 (Tiers 1-3)
MathA 13.495%B 51.000%Winner: GPT-5.5 ProΔ 37.5FrontierMath v2 (Tiers 1-3): Claude Sonnet 4.5 scored 13.495%; GPT-5.5 Pro scored 51.000%. GPT-5.5 Pro wins this benchmark. - Source ↗
FrontierMath v2 (Tier 4)
MathA 4.167%B 39.600%Winner: GPT-5.5 ProΔ 35.4FrontierMath v2 (Tier 4): Claude Sonnet 4.5 scored 4.167%; GPT-5.5 Pro scored 39.600%. GPT-5.5 Pro wins this benchmark.
Operational comparison
Runtime and commercial metrics are compared only when both models have a complete sourced value.
| Metric | Claude Sonnet 4.5 | GPT-5.5 Pro | Comparison |
|---|---|---|---|
| Input / output priceUSD per 1M tokens | Claude Sonnet 4.5$3 input / $15 output | GPT-5.5 Pro$30 input / $180 output | Claude Sonnet 4.5 has the lower combined listed price. |
| Generation speedtokens per second | Claude Sonnet 4.5Not available | GPT-5.5 ProNot available | A complete speed comparison is not available. |
| First-answer latencyseconds to first token | Claude Sonnet 4.5Not available | GPT-5.5 ProNot available | A complete latency comparison is not available. |
| Context windowmaximum listed tokens | Claude Sonnet 4.5200K | GPT-5.5 Pro1M | GPT-5.5 Pro lists the larger context window. |
Benchmark Deep Dive
AgenticGPT-5.5 Pro wins6 benchmarks
Coding1 benchmarks
| Benchmark | Claude Sonnet 4.5 | GPT-5.5 Pro | Result |
|---|---|---|---|
| SWE-bench VerifiedSource | 77.2% | — | Not comparable |
Reasoning2 benchmarks
KnowledgeClaude Sonnet 4.5 wins3 benchmarks
MathGPT-5.5 Pro wins4 benchmarks
Multimodal1 benchmarks
| Benchmark | Claude Sonnet 4.5 | GPT-5.5 Pro | Result |
|---|---|---|---|
| Design Arena WebsiteSource | 1219 | — | Not comparable |
Frequently Asked Questions (4)
Which is better, Claude Sonnet 4.5 or GPT-5.5 Pro?
GPT-5.5 Pro is ahead on BenchLM's BenchAlign leaderboard, 63.69 to 53.61. The biggest single separator in this matchup is FrontierMath v2 (Tiers 1-3), where the scores are 13.495% and 51.000%.
Which is better for knowledge tasks, Claude Sonnet 4.5 or GPT-5.5 Pro?
Claude Sonnet 4.5 has the edge for knowledge tasks in this comparison, averaging 83.4 versus 57.2. GPT-5.5 Pro stays close enough that the answer can still flip depending on your workload.
Which is better for math, Claude Sonnet 4.5 or GPT-5.5 Pro?
GPT-5.5 Pro has the edge for math in this comparison, averaging 48.1 versus 11.2. Inside this category, FrontierMath v2 (Tiers 1-3) is the benchmark that creates the most daylight between them.
Which is better for agentic tasks, Claude Sonnet 4.5 or GPT-5.5 Pro?
GPT-5.5 Pro has the edge for agentic tasks in this comparison, averaging 90.1 versus 55.4. Claude Sonnet 4.5 stays close enough that the answer can still flip depending on your workload.
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