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Model comparison

Claude Sonnet 5 vs GPT-5.5 Pro

Data verified

Head-to-head evidence from 4 shared benchmark results across 3 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.

65.32/100
Margin
1.6pts
← winning
63.69/100
1 category wins1 category wins

Public leaderboard positions: Claude Sonnet 5 #29 (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 5 and GPT-5.5 Pro share 4 comparable benchmark results. 2 of 8 categories are comparable. 32 results are unique to Claude Sonnet 5; 3 to GPT-5.5 Pro.

Updated July 23, 2026
Shared results
4
Claude Sonnet 5 only
32
GPT-5.5 Pro only
3
Comparable categories
2 / 8

Pick Claude Sonnet 5 if you want the stronger benchmark profile. GPT-5.5 Pro only becomes the better choice if agentic is the priority.

Confidence note. This is a partial-evidence comparison with 4 shared benchmark results across 3 evidence categories; 2 of 8 categories currently have scoreable aggregates for both models. Treat the verdict as directional until coverage is more balanced.

Why this result

Claude Sonnet 5 has the cleaner BenchAlign overall profile here, landing at 65.32 versus 63.69. It is a real lead, but still close enough that category-level strengths matter more than the headline number.

Claude Sonnet 5's sharpest advantage is in knowledge, where it averages 57.4 against 57.2. The single biggest benchmark swing on the page is BrowseComp, 84.7% to 90.1%. GPT-5.5 Pro does hit back in agentic, 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 $2.00 input / $10.00 output per 1M tokens for Claude Sonnet 5. That is roughly 18.0x on output cost alone.

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 scores and score margins for Claude Sonnet 5 and GPT-5.5 Pro
CategoryClaude Sonnet 5ΔGPT-5.5 Pro
AgenticClaude Sonnet 581.9Margin→ 8.2GPT-5.5 Pro90.1
KnowledgeClaude Sonnet 557.4Margin← 0.2GPT-5.5 Pro57.2
CodingClaude Sonnet 576.7MarginNo overlapGPT-5.5 ProNot measured
MathClaude Sonnet 5Not measuredMarginNo overlapGPT-5.5 Pro48.1
MultimodalClaude Sonnet 588.3MarginNo overlapGPT-5.5 ProNot measured

Decisive benchmark drivers

The largest measured benchmark gaps in this matchup, with exact reported values.

More
A · Claude Sonnet 5B · GPT-5.5 Pro

  1. BrowseComp

    Agentic
    Source ↗
    A 84.7%B 90.1%
    Winner: GPT-5.5 ProΔ 5.4
    BrowseComp: Claude Sonnet 5 scored 84.7%; GPT-5.5 Pro scored 90.1%. GPT-5.5 Pro wins this benchmark.

  2. HLE

    Knowledge
    Source ↗
    A 57.4%B 57.2%
    Winner: Claude Sonnet 5Δ 0.2
    HLE: Claude Sonnet 5 scored 57.4%; GPT-5.5 Pro scored 57.2%. Claude Sonnet 5 wins this benchmark.

Operational comparison

Runtime and commercial metrics are compared only when both models have a complete sourced value.

MetricClaude Sonnet 5GPT-5.5 ProComparison
Input / output priceUSD per 1M tokensClaude Sonnet 5$2 input / $10 outputGPT-5.5 Pro$30 input / $180 outputClaude Sonnet 5 has the lower combined listed price.
Generation speedtokens per secondClaude Sonnet 5Not availableGPT-5.5 ProNot availableA complete speed comparison is not available.
First-answer latencyseconds to first tokenClaude Sonnet 5Not availableGPT-5.5 ProNot availableA complete latency comparison is not available.
Context windowmaximum listed tokensClaude Sonnet 51MGPT-5.5 Pro1MListed context windows are equal.

Benchmark Deep Dive

AgenticGPT-5.5 Pro wins
BenchmarkClaude Sonnet 5GPT-5.5 ProResult
Terminal-Bench 2.0Source 80.4%—Not comparable
BrowseCompSource 84.7%90.1%GPT-5.5 Pro leads
HLE w/ toolsSource 57.4%—Not comparable
OSWorld-VerifiedSource 81.2%—Not comparable
GDPval-AASource 1607—Not comparable
AA Agentic IndexSource 46.7%—Not comparable
GDPval-AASource 55.4%—Not comparable
AA BriefcaseSource 1388—Not comparable
AA AutomationBenchSource 39.2%—Not comparable
AA EnterpriseOps-GymSource 44.7%—Not comparable
AA Harvey LABSource 90.1%—Not comparable
AA Tau3 BankingSource 28.2%—Not comparable
aaTerminalBench21Source 80.5%—Not comparable
Coding
BenchmarkClaude Sonnet 5GPT-5.5 ProResult
SWE-bench VerifiedSource 85.2%—Not comparable
SWE-bench ProSource 63.2%—Not comparable
SWE MultilingualSource 78.3%—Not comparable
SWE MultimodalSource 28.1%—Not comparable
Terminal-Bench 2.0Source 80.4%—Not comparable
FrontierCode 1.1 MainSource 42.7%—Not comparable
cursorBench32Source 61.5%—Not comparable
AA Coding IndexSource 71.5%—Not comparable
AA-SciCodeSource 53.6%—Not comparable
Reasoning
BenchmarkClaude Sonnet 5GPT-5.5 ProResult
AA-LCRSource 70.7%—Not comparable
CritPtSource 16.9%30.6%GPT-5.5 Pro leads
KnowledgeClaude Sonnet 5 wins
BenchmarkClaude Sonnet 5GPT-5.5 ProResult
HLESource 57.4%57.2%Claude Sonnet 5 leads
HLE w/o toolsSource 43.2%43.1%Claude Sonnet 5 leads
Artificial Analysis Intelligence IndexSource 53.4%—Not comparable
AA-GPQA DiamondSource 91.1%—Not comparable
AA-HLESource 39.6%—Not comparable
AA-Omniscience IndexSource 15.3%—Not comparable
AA-Omniscience AccuracySource 38.3%—Not comparable
AA-Omniscience Hallucination RateSource 37.3%—Not comparable
Math
BenchmarkClaude Sonnet 5GPT-5.5 ProResult
FrontierMath (legacy)Source —52.4%Not comparable
FrontierMath v2 (Tiers 1-3)Source —51.000%Not comparable
FrontierMath v2 (Tier 4)Source —39.600%Not comparable
Multimodal
BenchmarkClaude Sonnet 5GPT-5.5 ProResult
CharXivSource 88.3%—Not comparable
CharXiv w/o toolsSource 77%—Not comparable
AA-MMMU-ProSource 77.3%—Not comparable
Design Arena WebsiteSource 1314—Not comparable
Frequently Asked Questions (3)

Which is better, Claude Sonnet 5 or GPT-5.5 Pro?

Claude Sonnet 5 is ahead on BenchLM's BenchAlign leaderboard, 65.32 to 63.69. The biggest single separator in this matchup is BrowseComp, where the scores are 84.7% and 90.1%.

Which is better for knowledge tasks, Claude Sonnet 5 or GPT-5.5 Pro?

Claude Sonnet 5 has the edge for knowledge tasks in this comparison, averaging 57.4 versus 57.2. Inside this category, HLE is the benchmark that creates the most daylight between them.

Which is better for agentic tasks, Claude Sonnet 5 or GPT-5.5 Pro?

GPT-5.5 Pro has the edge for agentic tasks in this comparison, averaging 90.1 versus 81.9. Inside this category, BrowseComp is the benchmark that creates the most daylight between them.

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